Is it possible in Java to access private fields via reflection

Question

Is it possible in Java to access private field str via reflection  For example to get value of this field   class Test      private String str     public void setStr String value             str   value

User · Answer

Yes it is possible   You need to use the getDeclaredField method  instead of the getField method   with the name of your private field   Field privateField   Test class getDeclaredField  str      Additionally  you need to set this Field to be accessible  if you want to access a private field   privateField setAccessible true     Once that s done  you can use the get method on the Field instance  to access the value of the str field

User · Answer

Yes     Field f   Test class getDeclaredField  str      f setAccessible true    Very important  this allows the setting to work    String value    String  f get object     Then you use the field object to get the value on an instance of the class   Note that get method is often confusing for people  You have the field  but you don t have an instance of the object  You have to pass that to the get method

User · Answer

Yes  it absolutely is - assuming you ve got the appropriate security permissions  Use Field setAccessible true  first if you re accessing it from a different class   import java lang reflect     class Other       private String str      public void setStr String value                str   value           class Test       public static void main String   args             Just for the ease of a throwaway test  Don t            do this normally          throws Exception               Other t   new Other            t setStr  hi            Field field   Other class getDeclaredField  str            field setAccessible true           Object value   field get t           System out println value             And no  you shouldn t normally do this    it s subverting the intentions of the original author of the class  For example  there may well be validation applied in any situation where the field can normally be set  or other fields may be changed at the same time  You re effectively violating the intended level of encapsulation

[java] Is it possible in Java to access private fields via reflection

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