How do I find the caller of a method using stacktrace or reflection

Question

I need to find the caller of a method  Is it possible using stacktrace or reflection

User · Answer

I ve done this before   You can just create a new exception and grab the stack trace on it without throwing it  then examine the stack trace   As the other answer says though  it s extremely costly--don t do it in a tight loop   I ve done it before for a logging utility on an app where performance didn t matter much  Performance rarely matters much at all  actually--as long as you display the result to an action such as a button click quickly      It was before you could get the stack trace  exceptions just had  printStackTrace   so I had to redirect System out to a stream of my own creation  then  new Exception    printStackTrace    Redirect System out back and parse the stream   Fun stuff

User · Answer

StackTraceElement   stackTraceElements   Thread currentThread   getStackTrace     According to the Javadocs      The last element of the array represents the bottom of the stack  which is the least recent method invocation in the sequence     A StackTraceElement has getClassName    getFileName    getLineNumber   and getMethodName     You will have to experiment to determine which index you want  probably stackTraceElements 1  or  2

User · Answer

This method does the same thing but a little more simply and possibly a little more performant and in the event you are using reflection  it skips those frames automatically  The only issue is it may not be present in non-Sun JVMs  although it is included in the runtime classes of JRockit 1 4-- 1 6   Point is  it is not a public class    sun reflect Reflection          Returns the class of the method  lt code gt realFramesToSkip lt  code gt          frames up the stack  zero-based   ignoring frames associated         with java lang reflect Method invoke   and its implementation          The first frame is that associated with this method  so          lt code gt getCallerClass 0  lt  code gt  returns the Class object for         sun reflect Reflection  Frames associated with         java lang reflect Method invoke   and its implementation are         completely ignored and do not count toward the number of  real          frames skipped         public static native Class getCallerClass int realFramesToSkip     As far as what the realFramesToSkip value should be  the Sun 1 5 and 1 6 VM versions of java lang System  there is a package protected method called getCallerClass   which calls sun reflect Reflection getCallerClass 3   but in my helper utility class I used 4 since there is the added frame of the helper class invocation

User · Answer

I ve done this before   You can just create a new exception and grab the stack trace on it without throwing it  then examine the stack trace   As the other answer says though  it s extremely costly--don t do it in a tight loop   I ve done it before for a logging utility on an app where performance didn t matter much  Performance rarely matters much at all  actually--as long as you display the result to an action such as a button click quickly      It was before you could get the stack trace  exceptions just had  printStackTrace   so I had to redirect System out to a stream of my own creation  then  new Exception    printStackTrace    Redirect System out back and parse the stream   Fun stuff

User · Answer

use this method -   StackTraceElement   stacktrace   Thread currentThread   getStackTrace     stackTraceElement e   stacktrace 2    maybe this number needs to be corrected  System out println e getMethodName       Caller of method example Code is here -  public class TestString        public static void main String   args            TestString testString   new TestString            testString doit1            testString doit2            testString doit3            testString doit4               public void doit             StackTraceElement   stacktrace   Thread currentThread   getStackTrace            StackTraceElement e   stacktrace 2    maybe this number needs to be corrected         System out println e getMethodName                public void doit1             doit               public void doit2             doit               public void doit3             doit               public void doit4             doit

User · Answer

StackTraceElement   stackTraceElements   Thread currentThread   getStackTrace     According to the Javadocs      The last element of the array represents the bottom of the stack  which is the least recent method invocation in the sequence     A StackTraceElement has getClassName    getFileName    getLineNumber   and getMethodName     You will have to experiment to determine which index you want  probably stackTraceElements 1  or  2

User · Answer

Sounds like you re trying to avoid passing a reference to this into the method   Passing this is way better than finding the caller through the current stack trace   Refactoring to a more OO design is even better   You shouldn t need to know the caller   Pass a callback object if necessary

User · Answer

import java io ByteArrayOutputStream  import java io IOException  import java io PrintWriter   class DBConnection       String createdBy   null       DBConnection Throwable whoCreatedMe            ByteArrayOutputStream os   new ByteArrayOutputStream            PrintWriter pw   new PrintWriter os           whoCreatedMe printStackTrace pw           try               createdBy   os toString                pw close                os close              catch  IOException e                e printStackTrace                       public class ThrowableTest        public static void main String   args             Throwable createdBy   new Throwable                   Connection created from DBConnectionManager            DBConnection conn   new DBConnection createdBy           System out println conn createdBy             OR  public static interface ICallback lt T gt    T doOperation        public class TestCallerOfMethod        public static  lt T gt  T callTwo final ICallback lt T gt  c              Pass the object created at callee to the caller            From the passed object we can get  what is the callee name like below          System out println c getClass   getEnclosingMethod   getName             return c doOperation               public static boolean callOne            ICallback callBackInstance   new ICallback Boolean                Override             public Boolean doOperation                                  return true                                   return callTwo callBackInstance              public static void main String   args             callOne

User · Answer

Sounds like you re trying to avoid passing a reference to this into the method   Passing this is way better than finding the caller through the current stack trace   Refactoring to a more OO design is even better   You shouldn t need to know the caller   Pass a callback object if necessary

User · Answer

I ve done this before   You can just create a new exception and grab the stack trace on it without throwing it  then examine the stack trace   As the other answer says though  it s extremely costly--don t do it in a tight loop   I ve done it before for a logging utility on an app where performance didn t matter much  Performance rarely matters much at all  actually--as long as you display the result to an action such as a button click quickly      It was before you could get the stack trace  exceptions just had  printStackTrace   so I had to redirect System out to a stream of my own creation  then  new Exception    printStackTrace    Redirect System out back and parse the stream   Fun stuff

User · Answer

Get the method name for a depth in call stack   lt br   gt           Utility function           param depth depth in the call stack  0 means current method  1 means call method                 return method name                 public static String getMethodName final int depth                  final StackTraceElement   ste   new Throwable   getStackTrace               System  out println ste ste length-depth  getClassName       ste ste length-depth  getMethodName             return ste ste length - depth  getMethodName                For example  if you try to get the calling method line for debug purpose  you need to get past the Utility class  in which you code those static methods   old java1 4 code  just to illustrate a potential StackTraceElement usage                           Returns the first   class method line      of the first class not equal to  StackTraceUtils    lt br   gt              From the Stack Trace               return   class method line       never empty  first class past StackTraceUtils                       public static String getClassMethodLine                         return getClassMethodLine null                                      Returns the first   class method line      of the first class not equal to  StackTraceUtils  and aclass   lt br   gt              Allows to get past a certain class               param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils                return   class method line       never empty  because if aclass is not found  returns first class past StackTraceUtils                       public static String getClassMethodLine final Class aclass                        final StackTraceElement st   getCallingStackTraceElement aclass               final String amsg         st getClassName           st getMethodName           st getLineNumber                     lt     Thread currentThread   getName       gt                  return amsg                               Returns the first stack trace element of the first class not equal to  StackTraceUtils  or  LogUtils  and aClass   lt br   gt           Stored in array of the callstack   lt br   gt           Allows to get past a certain class            param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils             return stackTraceElement  never null  because if aClass is not found  returns first class past StackTraceUtils            throws AssertionFailedException if resulting statckTrace is null  RuntimeException                  public static StackTraceElement getCallingStackTraceElement final Class aclass                  final Throwable           t           new Throwable            final StackTraceElement   ste         t getStackTrace            int index   1          final int limit   ste length          StackTraceElement   st          ste index           String              className   st getClassName            boolean aclassfound   false          if aclass    null                        aclassfound   true                    StackTraceElement   resst   null          while index  lt  limit                        if shouldExamine className  aclass     true                                if resst    null                                        resst   st                                    if aclassfound    true                                        final StackTraceElement ast   onClassfound aclass  className  st                       if ast    null                                                resst   ast                          break                                                          else                                       if aclass    null  amp  amp  aclass getName   equals className     true                                                aclassfound   true                                                                    index   index   1              st          ste index               className   st getClassName                      if resst    null                           Assert isNotNull resst   stack trace should null      NO OTHERWISE circular dependencies              throw new AssertionFailedException StackTraceUtils getClassMethodLine       null argument      stack trace should null       NON-NLS-1                    return resst                 static private boolean shouldExamine String className  Class aclass                    final boolean res   StackTraceUtils class getName   equals className     false  amp  amp   className endsWith  LogUtils                   false     aclass   null  amp  amp  aclass getName   endsWith  LogUtils                return res                 static private StackTraceElement onClassfound Class aclass  String className  StackTraceElement st                    StackTraceElement   resst   null            if aclass    null  amp  amp  aclass getName   equals className     false                            resst   st                        if aclass    null                            resst   st                        return resst

User · Answer

I ve done this before   You can just create a new exception and grab the stack trace on it without throwing it  then examine the stack trace   As the other answer says though  it s extremely costly--don t do it in a tight loop   I ve done it before for a logging utility on an app where performance didn t matter much  Performance rarely matters much at all  actually--as long as you display the result to an action such as a button click quickly      It was before you could get the stack trace  exceptions just had  printStackTrace   so I had to redirect System out to a stream of my own creation  then  new Exception    printStackTrace    Redirect System out back and parse the stream   Fun stuff

User · Answer

This method does the same thing but a little more simply and possibly a little more performant and in the event you are using reflection  it skips those frames automatically  The only issue is it may not be present in non-Sun JVMs  although it is included in the runtime classes of JRockit 1 4-- 1 6   Point is  it is not a public class    sun reflect Reflection          Returns the class of the method  lt code gt realFramesToSkip lt  code gt          frames up the stack  zero-based   ignoring frames associated         with java lang reflect Method invoke   and its implementation          The first frame is that associated with this method  so          lt code gt getCallerClass 0  lt  code gt  returns the Class object for         sun reflect Reflection  Frames associated with         java lang reflect Method invoke   and its implementation are         completely ignored and do not count toward the number of  real          frames skipped         public static native Class getCallerClass int realFramesToSkip     As far as what the realFramesToSkip value should be  the Sun 1 5 and 1 6 VM versions of java lang System  there is a package protected method called getCallerClass   which calls sun reflect Reflection getCallerClass 3   but in my helper utility class I used 4 since there is the added frame of the helper class invocation

User · Answer

Java 9 - JEP 259  Stack-Walking API  JEP 259 provides an efficient standard API for stack walking that allows easy filtering of  and lazy access to  the information in stack traces  Before Stack-Walking API  common ways of accessing stack frames were      Throwable  getStackTrace and Thread  getStackTrace return an array of   StackTraceElement objects  which contain the class name and method   name of each stack-trace element       SecurityManager  getClassContext is a protected method  which allows a   SecurityManager subclass to access the class context       JDK-internal sun reflect Reflection  getCallerClass method which you shouldn t use anyway   Using these APIs are usually inefficient      These APIs require the VM to eagerly capture a snapshot of the entire   stack  and they return information representing the entire stack    There is no way to avoid the cost of examining all the frames if the   caller is only interested in the top few frames on the stack    In order to find the immediate caller s class  first obtain a StackWalker   StackWalker walker   StackWalker                             getInstance StackWalker Option RETAIN CLASS REFERENCE     Then either call the getCallerClass     Class lt   gt  callerClass   walker getCallerClass      or walk the StackFrames and get the first preceding StackFrame   walker walk frames - gt  frames        map StackWalker StackFrame  getDeclaringClass         skip 1         findFirst

User · Answer

An alternative solution can be found in a comment to this request for enhancement  It uses the getClassContext   method of a custom SecurityManager and seems to be faster than the stack trace method   The following program tests the speed of the different suggested methods  the most interesting bit is in the inner class SecurityManagerMethod           Test the speed of various methods for getting the caller class name     public class TestGetCallerClassName               Abstract class for testing different methods of getting the caller class name         private static abstract class GetCallerClassNameMethod         public abstract String getCallerClassName int callStackDepth         public abstract String getMethodName                    Uses the internal Reflection class         private static class ReflectionMethod extends GetCallerClassNameMethod         public String getCallerClassName int callStackDepth              return sun reflect Reflection getCallerClass callStackDepth  getName                   public String getMethodName               return  Reflection                           Get a stack trace from the current thread         private static class ThreadStackTraceMethod extends GetCallerClassNameMethod         public String  getCallerClassName int callStackDepth              return Thread currentThread   getStackTrace   callStackDepth  getClassName                   public String getMethodName               return  Current Thread StackTrace                           Get a stack trace from a new Throwable         private static class ThrowableStackTraceMethod extends GetCallerClassNameMethod          public String getCallerClassName int callStackDepth              return new Throwable   getStackTrace   callStackDepth  getClassName                   public String getMethodName               return  Throwable StackTrace                           Use the SecurityManager getClassContext           private static class SecurityManagerMethod extends GetCallerClassNameMethod         public String  getCallerClassName int callStackDepth              return mySecurityManager getCallerClassName callStackDepth                  public String getMethodName               return  SecurityManager                                A custom security manager that exposes the getClassContext   information                 static class MySecurityManager extends SecurityManager             public String getCallerClassName int callStackDepth                  return getClassContext   callStackDepth  getName                               private final static MySecurityManager mySecurityManager             new MySecurityManager                    Test all four methods         public static void main String   args          testMethod new ReflectionMethod           testMethod new ThreadStackTraceMethod           testMethod new ThrowableStackTraceMethod           testMethod new SecurityManagerMethod            private static void testMethod GetCallerClassNameMethod method          long startTime   System nanoTime          String className   null        for  int i   0  i  lt  1000000  i                className   method getCallerClassName 2                 printElapsedTime method getMethodName    startTime          private static void printElapsedTime String title  long startTime          System out println title            double  System nanoTime   - startTime   1000000     ms             An example of the output from my 2 4 GHz Intel Core 2 Duo MacBook running Java 1 6 0 17   Reflection  10 195 ms  Current Thread StackTrace  5886 964 ms  Throwable StackTrace  4700 073 ms  SecurityManager  1046 804 ms    The internal Reflection method is much faster than the others  Getting a stack trace from a newly created Throwable is faster than getting it from the current Thread  And among the non-internal ways of finding the caller class the custom SecurityManager seems to be the fastest   Update  As lyomi points out in this comment the sun reflect Reflection getCallerClass   method has been disabled by default in Java 7 update 40 and removed completely in Java 8  Read more about this in this issue in the Java bug database    Update 2  As zammbi has found  Oracle was forced to back out of the change that removed the sun reflect Reflection getCallerClass    It is still available in Java 8  but it is deprecated    Update 3  3 years after  Update on timing with current JVM    gt  java -version java version  1 8 0  Java TM  SE Runtime Environment  build 1 8 0-b132  Java HotSpot TM  64-Bit Server VM  build 25 0-b70  mixed mode   gt  java TestGetCallerClassName Reflection  0 194s  Current Thread StackTrace  3 887s  Throwable StackTrace  3 173s  SecurityManager  0 565s

User · Answer

An alternative solution can be found in a comment to this request for enhancement  It uses the getClassContext   method of a custom SecurityManager and seems to be faster than the stack trace method   The following program tests the speed of the different suggested methods  the most interesting bit is in the inner class SecurityManagerMethod           Test the speed of various methods for getting the caller class name     public class TestGetCallerClassName               Abstract class for testing different methods of getting the caller class name         private static abstract class GetCallerClassNameMethod         public abstract String getCallerClassName int callStackDepth         public abstract String getMethodName                    Uses the internal Reflection class         private static class ReflectionMethod extends GetCallerClassNameMethod         public String getCallerClassName int callStackDepth              return sun reflect Reflection getCallerClass callStackDepth  getName                   public String getMethodName               return  Reflection                           Get a stack trace from the current thread         private static class ThreadStackTraceMethod extends GetCallerClassNameMethod         public String  getCallerClassName int callStackDepth              return Thread currentThread   getStackTrace   callStackDepth  getClassName                   public String getMethodName               return  Current Thread StackTrace                           Get a stack trace from a new Throwable         private static class ThrowableStackTraceMethod extends GetCallerClassNameMethod          public String getCallerClassName int callStackDepth              return new Throwable   getStackTrace   callStackDepth  getClassName                   public String getMethodName               return  Throwable StackTrace                           Use the SecurityManager getClassContext           private static class SecurityManagerMethod extends GetCallerClassNameMethod         public String  getCallerClassName int callStackDepth              return mySecurityManager getCallerClassName callStackDepth                  public String getMethodName               return  SecurityManager                                A custom security manager that exposes the getClassContext   information                 static class MySecurityManager extends SecurityManager             public String getCallerClassName int callStackDepth                  return getClassContext   callStackDepth  getName                               private final static MySecurityManager mySecurityManager             new MySecurityManager                    Test all four methods         public static void main String   args          testMethod new ReflectionMethod           testMethod new ThreadStackTraceMethod           testMethod new ThrowableStackTraceMethod           testMethod new SecurityManagerMethod            private static void testMethod GetCallerClassNameMethod method          long startTime   System nanoTime          String className   null        for  int i   0  i  lt  1000000  i                className   method getCallerClassName 2                 printElapsedTime method getMethodName    startTime          private static void printElapsedTime String title  long startTime          System out println title            double  System nanoTime   - startTime   1000000     ms             An example of the output from my 2 4 GHz Intel Core 2 Duo MacBook running Java 1 6 0 17   Reflection  10 195 ms  Current Thread StackTrace  5886 964 ms  Throwable StackTrace  4700 073 ms  SecurityManager  1046 804 ms    The internal Reflection method is much faster than the others  Getting a stack trace from a newly created Throwable is faster than getting it from the current Thread  And among the non-internal ways of finding the caller class the custom SecurityManager seems to be the fastest   Update  As lyomi points out in this comment the sun reflect Reflection getCallerClass   method has been disabled by default in Java 7 update 40 and removed completely in Java 8  Read more about this in this issue in the Java bug database    Update 2  As zammbi has found  Oracle was forced to back out of the change that removed the sun reflect Reflection getCallerClass    It is still available in Java 8  but it is deprecated    Update 3  3 years after  Update on timing with current JVM    gt  java -version java version  1 8 0  Java TM  SE Runtime Environment  build 1 8 0-b132  Java HotSpot TM  64-Bit Server VM  build 25 0-b70  mixed mode   gt  java TestGetCallerClassName Reflection  0 194s  Current Thread StackTrace  3 887s  Throwable StackTrace  3 173s  SecurityManager  0 565s

User · Answer

StackTraceElement   stackTraceElements   Thread currentThread   getStackTrace     According to the Javadocs      The last element of the array represents the bottom of the stack  which is the least recent method invocation in the sequence     A StackTraceElement has getClassName    getFileName    getLineNumber   and getMethodName     You will have to experiment to determine which index you want  probably stackTraceElements 1  or  2

User · Answer

use this method -   StackTraceElement   stacktrace   Thread currentThread   getStackTrace     stackTraceElement e   stacktrace 2    maybe this number needs to be corrected  System out println e getMethodName       Caller of method example Code is here -  public class TestString        public static void main String   args            TestString testString   new TestString            testString doit1            testString doit2            testString doit3            testString doit4               public void doit             StackTraceElement   stacktrace   Thread currentThread   getStackTrace            StackTraceElement e   stacktrace 2    maybe this number needs to be corrected         System out println e getMethodName                public void doit1             doit               public void doit2             doit               public void doit3             doit               public void doit4             doit

User · Answer

private void parseExceptionContents        final Exception exception        final OutputStream out             final StackTraceElement   stackTrace   exception getStackTrace          int index   0        for  StackTraceElement element   stackTrace                   final String exceptionMsg                  Exception thrown from     element getMethodName                   in class     element getClassName        on line number                 element getLineNumber       of file     element getFileName                   try                        out write  headerLine   newLine  getBytes                 out write  headerTitlePortion   index     newLine  getBytes                  out write  headerLine   newLine  getBytes                 out write  exceptionMsg   newLine   newLine  getBytes                 out write                   Exception toString      element toString     newLine  getBytes                         catch  IOException ioEx                         System err println                    IOException encountered while trying to write                     StackTraceElement data to provided OutputStream  n                   ioEx getMessage

User · Answer

This method does the same thing but a little more simply and possibly a little more performant and in the event you are using reflection  it skips those frames automatically  The only issue is it may not be present in non-Sun JVMs  although it is included in the runtime classes of JRockit 1 4-- 1 6   Point is  it is not a public class    sun reflect Reflection          Returns the class of the method  lt code gt realFramesToSkip lt  code gt          frames up the stack  zero-based   ignoring frames associated         with java lang reflect Method invoke   and its implementation          The first frame is that associated with this method  so          lt code gt getCallerClass 0  lt  code gt  returns the Class object for         sun reflect Reflection  Frames associated with         java lang reflect Method invoke   and its implementation are         completely ignored and do not count toward the number of  real          frames skipped         public static native Class getCallerClass int realFramesToSkip     As far as what the realFramesToSkip value should be  the Sun 1 5 and 1 6 VM versions of java lang System  there is a package protected method called getCallerClass   which calls sun reflect Reflection getCallerClass 3   but in my helper utility class I used 4 since there is the added frame of the helper class invocation

User · Answer

Here is a part of the code that I made based in the hints showed in this topic  Hope it helps    Feel free to make any suggestions to improve this code  please tell me   The counter   public class InstanceCount      private static Map lt Integer  CounterInstanceLog gt  instanceMap   new HashMap lt Integer  CounterInstanceLog gt     private CounterInstanceLog counterInstanceLog        public void count             counterInstanceLog  new counterInstanceLog        if counterInstanceLog getIdHashCode      0       try           if  instanceMap  containsKey counterInstanceLog getIdHashCode                counterInstanceLog  instanceMap  get counterInstanceLog getIdHashCode                counterInstanceLog incrementCounter                 instanceMap  put counterInstanceLog getIdHashCode    counterInstanceLog                        And the object   public class CounterInstanceLog      private int idHashCode      private StackTraceElement   arrayStackTraceElements      private int instanceCount      private String callerClassName       private StackTraceElement getProjectClasses int depth          if depth lt  10           getCallerClassName sun reflect Reflection getCallerClass depth  getName             if getCallerClassName   startsWith  com yourproject model                 setStackTraceElements Thread currentThread   getStackTrace                 setIdHashCode            return arrayStackTraceElements depth                        2 because one new item are added to the stackflow         return getProjectClasses profundidade 2                     else          return null                     private void setIdHashCode             if getNomeClasse      null               this idHashCode    getCallerClassName    hashCode                         public void incrementaContador         this instanceCount             getters and setters

User · Answer

Sounds like you re trying to avoid passing a reference to this into the method   Passing this is way better than finding the caller through the current stack trace   Refactoring to a more OO design is even better   You shouldn t need to know the caller   Pass a callback object if necessary

User · Answer

Get the method name for a depth in call stack   lt br   gt           Utility function           param depth depth in the call stack  0 means current method  1 means call method                 return method name                 public static String getMethodName final int depth                  final StackTraceElement   ste   new Throwable   getStackTrace               System  out println ste ste length-depth  getClassName       ste ste length-depth  getMethodName             return ste ste length - depth  getMethodName                For example  if you try to get the calling method line for debug purpose  you need to get past the Utility class  in which you code those static methods   old java1 4 code  just to illustrate a potential StackTraceElement usage                           Returns the first   class method line      of the first class not equal to  StackTraceUtils    lt br   gt              From the Stack Trace               return   class method line       never empty  first class past StackTraceUtils                       public static String getClassMethodLine                         return getClassMethodLine null                                      Returns the first   class method line      of the first class not equal to  StackTraceUtils  and aclass   lt br   gt              Allows to get past a certain class               param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils                return   class method line       never empty  because if aclass is not found  returns first class past StackTraceUtils                       public static String getClassMethodLine final Class aclass                        final StackTraceElement st   getCallingStackTraceElement aclass               final String amsg         st getClassName           st getMethodName           st getLineNumber                     lt     Thread currentThread   getName       gt                  return amsg                               Returns the first stack trace element of the first class not equal to  StackTraceUtils  or  LogUtils  and aClass   lt br   gt           Stored in array of the callstack   lt br   gt           Allows to get past a certain class            param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils             return stackTraceElement  never null  because if aClass is not found  returns first class past StackTraceUtils            throws AssertionFailedException if resulting statckTrace is null  RuntimeException                  public static StackTraceElement getCallingStackTraceElement final Class aclass                  final Throwable           t           new Throwable            final StackTraceElement   ste         t getStackTrace            int index   1          final int limit   ste length          StackTraceElement   st          ste index           String              className   st getClassName            boolean aclassfound   false          if aclass    null                        aclassfound   true                    StackTraceElement   resst   null          while index  lt  limit                        if shouldExamine className  aclass     true                                if resst    null                                        resst   st                                    if aclassfound    true                                        final StackTraceElement ast   onClassfound aclass  className  st                       if ast    null                                                resst   ast                          break                                                          else                                       if aclass    null  amp  amp  aclass getName   equals className     true                                                aclassfound   true                                                                    index   index   1              st          ste index               className   st getClassName                      if resst    null                           Assert isNotNull resst   stack trace should null      NO OTHERWISE circular dependencies              throw new AssertionFailedException StackTraceUtils getClassMethodLine       null argument      stack trace should null       NON-NLS-1                    return resst                 static private boolean shouldExamine String className  Class aclass                    final boolean res   StackTraceUtils class getName   equals className     false  amp  amp   className endsWith  LogUtils                   false     aclass   null  amp  amp  aclass getName   endsWith  LogUtils                return res                 static private StackTraceElement onClassfound Class aclass  String className  StackTraceElement st                    StackTraceElement   resst   null            if aclass    null  amp  amp  aclass getName   equals className     false                            resst   st                        if aclass    null                            resst   st                        return resst

User · Answer

Sounds like you re trying to avoid passing a reference to this into the method   Passing this is way better than finding the caller through the current stack trace   Refactoring to a more OO design is even better   You shouldn t need to know the caller   Pass a callback object if necessary

User · Answer

This method does the same thing but a little more simply and possibly a little more performant and in the event you are using reflection  it skips those frames automatically  The only issue is it may not be present in non-Sun JVMs  although it is included in the runtime classes of JRockit 1 4-- 1 6   Point is  it is not a public class    sun reflect Reflection          Returns the class of the method  lt code gt realFramesToSkip lt  code gt          frames up the stack  zero-based   ignoring frames associated         with java lang reflect Method invoke   and its implementation          The first frame is that associated with this method  so          lt code gt getCallerClass 0  lt  code gt  returns the Class object for         sun reflect Reflection  Frames associated with         java lang reflect Method invoke   and its implementation are         completely ignored and do not count toward the number of  real          frames skipped         public static native Class getCallerClass int realFramesToSkip     As far as what the realFramesToSkip value should be  the Sun 1 5 and 1 6 VM versions of java lang System  there is a package protected method called getCallerClass   which calls sun reflect Reflection getCallerClass 3   but in my helper utility class I used 4 since there is the added frame of the helper class invocation

User · Answer

StackTraceElement   stackTraceElements   Thread currentThread   getStackTrace     According to the Javadocs      The last element of the array represents the bottom of the stack  which is the least recent method invocation in the sequence     A StackTraceElement has getClassName    getFileName    getLineNumber   and getMethodName     You will have to experiment to determine which index you want  probably stackTraceElements 1  or  2

User · Answer

import java io ByteArrayOutputStream  import java io IOException  import java io PrintWriter   class DBConnection       String createdBy   null       DBConnection Throwable whoCreatedMe            ByteArrayOutputStream os   new ByteArrayOutputStream            PrintWriter pw   new PrintWriter os           whoCreatedMe printStackTrace pw           try               createdBy   os toString                pw close                os close              catch  IOException e                e printStackTrace                       public class ThrowableTest        public static void main String   args             Throwable createdBy   new Throwable                   Connection created from DBConnectionManager            DBConnection conn   new DBConnection createdBy           System out println conn createdBy             OR  public static interface ICallback lt T gt    T doOperation        public class TestCallerOfMethod        public static  lt T gt  T callTwo final ICallback lt T gt  c              Pass the object created at callee to the caller            From the passed object we can get  what is the callee name like below          System out println c getClass   getEnclosingMethod   getName             return c doOperation               public static boolean callOne            ICallback callBackInstance   new ICallback Boolean                Override             public Boolean doOperation                                  return true                                   return callTwo callBackInstance              public static void main String   args             callOne

User · Answer

Oneliner    Thread currentThread   getStackTrace   2  getMethodName     Note that you might need to replace the 2 with 1

User · Answer

Oneliner    Thread currentThread   getStackTrace   2  getMethodName     Note that you might need to replace the 2 with 1

User · Answer

private void parseExceptionContents        final Exception exception        final OutputStream out             final StackTraceElement   stackTrace   exception getStackTrace          int index   0        for  StackTraceElement element   stackTrace                   final String exceptionMsg                  Exception thrown from     element getMethodName                   in class     element getClassName        on line number                 element getLineNumber       of file     element getFileName                   try                        out write  headerLine   newLine  getBytes                 out write  headerTitlePortion   index     newLine  getBytes                  out write  headerLine   newLine  getBytes                 out write  exceptionMsg   newLine   newLine  getBytes                 out write                   Exception toString      element toString     newLine  getBytes                         catch  IOException ioEx                         System err println                    IOException encountered while trying to write                     StackTraceElement data to provided OutputStream  n                   ioEx getMessage

User · Answer

Get the method name for a depth in call stack   lt br   gt           Utility function           param depth depth in the call stack  0 means current method  1 means call method                 return method name                 public static String getMethodName final int depth                  final StackTraceElement   ste   new Throwable   getStackTrace               System  out println ste ste length-depth  getClassName       ste ste length-depth  getMethodName             return ste ste length - depth  getMethodName                For example  if you try to get the calling method line for debug purpose  you need to get past the Utility class  in which you code those static methods   old java1 4 code  just to illustrate a potential StackTraceElement usage                           Returns the first   class method line      of the first class not equal to  StackTraceUtils    lt br   gt              From the Stack Trace               return   class method line       never empty  first class past StackTraceUtils                       public static String getClassMethodLine                         return getClassMethodLine null                                      Returns the first   class method line      of the first class not equal to  StackTraceUtils  and aclass   lt br   gt              Allows to get past a certain class               param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils                return   class method line       never empty  because if aclass is not found  returns first class past StackTraceUtils                       public static String getClassMethodLine final Class aclass                        final StackTraceElement st   getCallingStackTraceElement aclass               final String amsg         st getClassName           st getMethodName           st getLineNumber                     lt     Thread currentThread   getName       gt                  return amsg                               Returns the first stack trace element of the first class not equal to  StackTraceUtils  or  LogUtils  and aClass   lt br   gt           Stored in array of the callstack   lt br   gt           Allows to get past a certain class            param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils             return stackTraceElement  never null  because if aClass is not found  returns first class past StackTraceUtils            throws AssertionFailedException if resulting statckTrace is null  RuntimeException                  public static StackTraceElement getCallingStackTraceElement final Class aclass                  final Throwable           t           new Throwable            final StackTraceElement   ste         t getStackTrace            int index   1          final int limit   ste length          StackTraceElement   st          ste index           String              className   st getClassName            boolean aclassfound   false          if aclass    null                        aclassfound   true                    StackTraceElement   resst   null          while index  lt  limit                        if shouldExamine className  aclass     true                                if resst    null                                        resst   st                                    if aclassfound    true                                        final StackTraceElement ast   onClassfound aclass  className  st                       if ast    null                                                resst   ast                          break                                                          else                                       if aclass    null  amp  amp  aclass getName   equals className     true                                                aclassfound   true                                                                    index   index   1              st          ste index               className   st getClassName                      if resst    null                           Assert isNotNull resst   stack trace should null      NO OTHERWISE circular dependencies              throw new AssertionFailedException StackTraceUtils getClassMethodLine       null argument      stack trace should null       NON-NLS-1                    return resst                 static private boolean shouldExamine String className  Class aclass                    final boolean res   StackTraceUtils class getName   equals className     false  amp  amp   className endsWith  LogUtils                   false     aclass   null  amp  amp  aclass getName   endsWith  LogUtils                return res                 static private StackTraceElement onClassfound Class aclass  String className  StackTraceElement st                    StackTraceElement   resst   null            if aclass    null  amp  amp  aclass getName   equals className     false                            resst   st                        if aclass    null                            resst   st                        return resst

User · Answer

Java 9 - JEP 259  Stack-Walking API  JEP 259 provides an efficient standard API for stack walking that allows easy filtering of  and lazy access to  the information in stack traces  Before Stack-Walking API  common ways of accessing stack frames were      Throwable  getStackTrace and Thread  getStackTrace return an array of   StackTraceElement objects  which contain the class name and method   name of each stack-trace element       SecurityManager  getClassContext is a protected method  which allows a   SecurityManager subclass to access the class context       JDK-internal sun reflect Reflection  getCallerClass method which you shouldn t use anyway   Using these APIs are usually inefficient      These APIs require the VM to eagerly capture a snapshot of the entire   stack  and they return information representing the entire stack    There is no way to avoid the cost of examining all the frames if the   caller is only interested in the top few frames on the stack    In order to find the immediate caller s class  first obtain a StackWalker   StackWalker walker   StackWalker                             getInstance StackWalker Option RETAIN CLASS REFERENCE     Then either call the getCallerClass     Class lt   gt  callerClass   walker getCallerClass      or walk the StackFrames and get the first preceding StackFrame   walker walk frames - gt  frames        map StackWalker StackFrame  getDeclaringClass         skip 1         findFirst

User · Answer

Get the method name for a depth in call stack   lt br   gt           Utility function           param depth depth in the call stack  0 means current method  1 means call method                 return method name                 public static String getMethodName final int depth                  final StackTraceElement   ste   new Throwable   getStackTrace               System  out println ste ste length-depth  getClassName       ste ste length-depth  getMethodName             return ste ste length - depth  getMethodName                For example  if you try to get the calling method line for debug purpose  you need to get past the Utility class  in which you code those static methods   old java1 4 code  just to illustrate a potential StackTraceElement usage                           Returns the first   class method line      of the first class not equal to  StackTraceUtils    lt br   gt              From the Stack Trace               return   class method line       never empty  first class past StackTraceUtils                       public static String getClassMethodLine                         return getClassMethodLine null                                      Returns the first   class method line      of the first class not equal to  StackTraceUtils  and aclass   lt br   gt              Allows to get past a certain class               param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils                return   class method line       never empty  because if aclass is not found  returns first class past StackTraceUtils                       public static String getClassMethodLine final Class aclass                        final StackTraceElement st   getCallingStackTraceElement aclass               final String amsg         st getClassName           st getMethodName           st getLineNumber                     lt     Thread currentThread   getName       gt                  return amsg                               Returns the first stack trace element of the first class not equal to  StackTraceUtils  or  LogUtils  and aClass   lt br   gt           Stored in array of the callstack   lt br   gt           Allows to get past a certain class            param aclass class to get pass in the stack trace  If null  only try to get past StackTraceUtils             return stackTraceElement  never null  because if aClass is not found  returns first class past StackTraceUtils            throws AssertionFailedException if resulting statckTrace is null  RuntimeException                  public static StackTraceElement getCallingStackTraceElement final Class aclass                  final Throwable           t           new Throwable            final StackTraceElement   ste         t getStackTrace            int index   1          final int limit   ste length          StackTraceElement   st          ste index           String              className   st getClassName            boolean aclassfound   false          if aclass    null                        aclassfound   true                    StackTraceElement   resst   null          while index  lt  limit                        if shouldExamine className  aclass     true                                if resst    null                                        resst   st                                    if aclassfound    true                                        final StackTraceElement ast   onClassfound aclass  className  st                       if ast    null                                                resst   ast                          break                                                          else                                       if aclass    null  amp  amp  aclass getName   equals className     true                                                aclassfound   true                                                                    index   index   1              st          ste index               className   st getClassName                      if resst    null                           Assert isNotNull resst   stack trace should null      NO OTHERWISE circular dependencies              throw new AssertionFailedException StackTraceUtils getClassMethodLine       null argument      stack trace should null       NON-NLS-1                    return resst                 static private boolean shouldExamine String className  Class aclass                    final boolean res   StackTraceUtils class getName   equals className     false  amp  amp   className endsWith  LogUtils                   false     aclass   null  amp  amp  aclass getName   endsWith  LogUtils                return res                 static private StackTraceElement onClassfound Class aclass  String className  StackTraceElement st                    StackTraceElement   resst   null            if aclass    null  amp  amp  aclass getName   equals className     false                            resst   st                        if aclass    null                            resst   st                        return resst

User · Answer

Here is a part of the code that I made based in the hints showed in this topic  Hope it helps    Feel free to make any suggestions to improve this code  please tell me   The counter   public class InstanceCount      private static Map lt Integer  CounterInstanceLog gt  instanceMap   new HashMap lt Integer  CounterInstanceLog gt     private CounterInstanceLog counterInstanceLog        public void count             counterInstanceLog  new counterInstanceLog        if counterInstanceLog getIdHashCode      0       try           if  instanceMap  containsKey counterInstanceLog getIdHashCode                counterInstanceLog  instanceMap  get counterInstanceLog getIdHashCode                counterInstanceLog incrementCounter                 instanceMap  put counterInstanceLog getIdHashCode    counterInstanceLog                        And the object   public class CounterInstanceLog      private int idHashCode      private StackTraceElement   arrayStackTraceElements      private int instanceCount      private String callerClassName       private StackTraceElement getProjectClasses int depth          if depth lt  10           getCallerClassName sun reflect Reflection getCallerClass depth  getName             if getCallerClassName   startsWith  com yourproject model                 setStackTraceElements Thread currentThread   getStackTrace                 setIdHashCode            return arrayStackTraceElements depth                        2 because one new item are added to the stackflow         return getProjectClasses profundidade 2                     else          return null                     private void setIdHashCode             if getNomeClasse      null               this idHashCode    getCallerClassName    hashCode                         public void incrementaContador         this instanceCount             getters and setters

[java] How do I find the caller of a method using stacktrace or reflection?

Examples related to java

Examples related to stack-trace