java.lang.reflect.Field.get() Method Example

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Description

The java.lang.reflect.Field.get(Object obj) method returns the value of the field represented by this Field, on the specified object. The value is automatically wrapped in an object if it has a primitive type.

Declaration

Following is the declaration for java.lang.reflect.Field.get(Object obj) method.

public Object get(Object obj)
   throws IllegalArgumentException, IllegalAccessException

Parameters

obj − object from which the represented field's value is to be extracted.

Returns

the value of the represented field in object obj; primitive values are wrapped in an appropriate object before being returned.

Exceptions

• IllegalAccessException − if this Field object is enforcing Java language access control and the underlying field is inaccessible.

• IllegalArgumentException − if the specified object is not an instance of the class or interface declaring the underlying field (or a subclass or implementor thereof).

• NullPointerException − if the specified object is null and the field is an instance field.

• ExceptionInInitializerError − if the initialization provoked by this method fails.

Example

The following example shows the usage of java.lang.reflect.Field.get(Object obj) method.

package com.tutorialspoint;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Field;

public class FieldDemo {

   public static void main(String[] args) throws NoSuchFieldException, 
      SecurityException, IllegalArgumentException, IllegalAccessException {
          
      SampleClass sampleObject = new SampleClass();
      sampleObject.setSampleField("data");
      
      Field field = SampleClass.class.getField("sampleField");
      System.out.println(field.get(sampleObject));
   }
}

@CustomAnnotation(name = "SampleClass",  value = "Sample Class Annotation")
class SampleClass {

   @CustomAnnotation(name="sampleClassField",  value = "Sample Field Annotation")
   public String sampleField;
    
   public String getSampleField() {
      return sampleField;
   }

   public void setSampleField(String sampleField) {
      this.sampleField = sampleField;
   }
}

@Retention(RetentionPolicy.RUNTIME)
@interface CustomAnnotation {
   public String name();
   public String value();
}

Let us compile and run the above program, this will produce the following result −

data