How to call getClass from a static method in Java

Question

I have a class that must have some static methods  Inside these static methods I need to call the method getClass   to make the following call   public static void startMusic       URL songPath   getClass   getClassLoader   getResource  background midi        However Eclipse tells me   Cannot make a static reference to the non-static method getClass    from the type Object   What is the appropriate way to fix this compile time error

User · Answer

Try it  Thread currentThread   getStackTrace   1  getClassName     Or  Thread currentThread   getStackTrace   2  getClassName

User · Answer

I wrestled with this myself   A nice trick is to use use the current thread to get a ClassLoader when in a static context   This will work in a Hadoop MapReduce as well   Other methods work when running locally  but return a null InputStream when used in a MapReduce   public static InputStream getResource String resource  throws Exception      ClassLoader cl   Thread currentThread   getContextClassLoader       InputStream is   cl getResourceAsStream resource      return is

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As for the code example in the question  the standard solution is to reference the class explicitly by its name  and it is even possible to do without getClassLoader   call   class MyClass     public static void startMusic         URL songPath   MyClass class getResource  background midi            This approach still has a back side that it is not very safe against copy paste errors in case you need to replicate this code to a number of similar classes   And as for the exact question in the headline  there is a trick posted in the adjacent thread   Class currentClass   new Object       getClass   getEnclosingClass      It uses a nested anonymous Object subclass to get hold of the execution context  This trick has a benefit of being copy paste safe     Caution when using this in a Base Class that other classes inherit from   It is also worth noting that if this snippet is shaped as a static method of some base class then currentClass value will always be a reference to that base class rather than to any subclass that may be using that method

User · Answer

In Java7  you can do this in static methods fields   MethodHandles lookup   lookupClass

User · Answer

The Answer  Just use TheClassName class instead of getClass     Declaring Loggers  Since this gets so much attention for a specific usecase--to provide an easy way to insert log declarations--I thought I d add my thoughts on that   Log frameworks often expect the log to be constrained to a certain context  say a fully-qualified class name   So they are not copy-pastable without modification   Suggestions for paste-safe log declarations are provided in other answers  but they have downsides such as inflating bytecode or adding runtime introspection   I don t recommend these   Copy-paste is an editor concern  so an editor solution is most appropriate   In IntelliJ  I recommend adding a Live Template    Use  log  as the abbreviation Use private static final org slf4j Logger logger   org slf4j LoggerFactory getLogger  CLASS  class   as the template text   Click Edit Variables and add CLASS using the expression className   Check the boxes to reformat and shorten FQ names  Change the context to Java  declaration    Now if you type log lt tab gt  it ll automatically expand to   private static final Logger logger   LoggerFactory getLogger ClassName class     And automatically reformat and optimize the imports for you

User · Answer

Suppose there is a Utility class  then sample code would be -       URL url   Utility class getClassLoader   getResource  customLocation   concat  abc txt       CustomLocation - if any folder structure within resources otherwise remove this string literal

User · Answer

Try something like this  It works for me  Logg  Class name       String level           Properties prop   new Properties         InputStream in               Logg class getResourceAsStream  resources  config         if  in    null            prop load in         else           throw new FileNotFoundException  property file      in      not found in the classpath               level   prop getProperty  Level

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I had the same problem   but to solve it just modify your code as following  public static void startMusic     URL songPath   YouClassName class getClassLoader   getResource  quot background midi quot       this worked fine with me hope it will also work fine with you

User · Answer

Simply use a class literal  i e  NameOfClass class

User · Answer

getClass   method is defined in Object class with the following signature      public final Class getClass     Since it is not defined as static  you can not call it within a static code block  See these answers for more information  Q1  Q2  Q3   If you re in a static context  then you have to use the class literal expression to get the Class  so you basically have to do like      Foo class   This type of expression is called Class Literals and they are explained in Java Language Specification Book as follows      A class literal is an expression consisting of the name of a class  interface  array  or primitive type followed by a     and the token class  The type of a class literal is Class  It evaluates to the Class object for the named type  or for void  as defined by the defining class loader of the class of the current instance    You can also find information about this subject on API documentation for Class

[java] How to call getClass() from a static method in Java?

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