Reflection generic get field value

Question

I am trying to receive field value via reflection  The problem is I don t know the fields type and have to decide it while getting the value   This code results with this exception   Can not set java lang String field com    fieldName to java lang String  Field field   object getClass   getDeclaredField fieldName   field setAccessible true    Class lt   gt  targetType   field getType    Object objectValue   targetType newInstance     Object value   field get objectValue     I tried to cast  but I get compilation errors    field get  targetType objectValue    or  targetType objectValue   targetType newInstance      How can I do this

User · Answer

Integer typeValue   0   try        Class lt Types gt  types   Types class       java lang reflect Field field   types getDeclaredField  Type         field setAccessible true        Object value   field get types        typeValue    Integer  value     catch  Exception e         e printStackTrace

User · Answer

Although it s not really clear to me what you re trying to achieve  I spotted an obvious error in your code  Field get   expects the object which contains the field as argument  not some  possible  value of that field  So you should have field get object    Since you appear to be looking for the field value  you can obtain that as   Object objectValue   field get object     No need to instantiate the field type and create some empty default value  or maybe there s something I missed

User · Answer

You are calling get with the wrong argument   It should be   Object value   field get object

User · Answer

I post my solution in Kotlin  but it can work with java objects as well  I create a function extension so any object can use this function   fun Any iterateOverComponents      val fields   this javaClass declaredFields  fields forEachIndexed   i  field - gt       fields i  isAccessible   true        get value of the fields     val value   fields i  get this          print result     Log w  Msg    Value of Field                 fields i  name                 is     value       Take a look at this webpage  https   www geeksforgeeks org field-get-method-in-java-with-examples

User · Answer

Like answered before  you should use   Object value   field get objectInstance     Another way  which is sometimes prefered  is calling the getter dynamically  example code   public static Object runGetter Field field  BaseValidationObject o           MZ  Find the correct method     for  Method method   o getMethods                  if   method getName   startsWith  get     amp  amp   method getName   length       field getName   length     3                          if  method getName   toLowerCase   endsWith field getName   toLowerCase                                      MZ  Method found  run it                 try                                       return method invoke o                                     catch  IllegalAccessException e                                        Logger fatal  Could not determine method      method getName                                       catch  InvocationTargetException e                                        Logger fatal  Could not determine method      method getName                                                            return null      Also be aware that when your class inherits from another class  you need to recursively determine the Field  for instance  to fetch all Fields of a given class       for  Class lt   gt  c   someClass  c    null  c   c getSuperclass                  Field   fields   c getDeclaredFields            for  Field classField   fields                        result add classField

User · Answer

Here is the example I used for get the field name also the field value   Hope This will help to someone TestModel model   new TestModel   MyDate    MyTime    OUT      Get All the fields of the class  Field   fields   model getClass   getDeclaredFields      If the field is private make the field to accessible true fields 0  setAccessible true     Get the field name   System out println fields 0  getName       Get the field value System out println fields 0  get model

User · Answer

I use the reflections in the toString   implementation of my preference class to see the class members and values  simple and quick debugging    The simplified code I m using    Override public String toString         StringBuilder sb   new StringBuilder         Class lt   gt  thisClass   null      try           thisClass   Class forName this getClass   getName              Field   aClassFields   thisClass getDeclaredFields            sb append this getClass   getSimpleName                     for Field f   aClassFields               String fName   f getName                sb append       f getType            fName           f get this                             sb append             catch  Exception e            e printStackTrace               return sb toString        I hope that it will help someone  because I also have searched

User · Answer

You should pass the object to get method of the field  so    Field field   object getClass   getDeclaredField fieldName         field setAccessible true     Object value   field get object

[java] Reflection generic get field value

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