Java Class getFields() Method

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Description

The Java Class getFields() method returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object.The method returns an array of length 0 if the class or interface has no accessible public fields, or if it represents an array class, a primitive type, or void.

Declaration

Following is the declaration for java.lang.Class.getFields() method

public Field[] getFields() throws SecurityException

Parameters

NA

Return Value

This method returns the array of Field objects representing the public fields.

Exception

SecurityException − If a security manager, s, is present.

Getting Fields of a Class Example

The following example shows the usage of java.lang.Class.getFields() method. In this program, we've retrieved class of java.awt.Label and then using getFields() method, all fields are retrieved and printed them.

package com.tutorialspoint;

public class ClassDemo {

   public static void main(String[] args) {

      try {
         Class cls = Class.forName("java.awt.Label");
         System.out.println("Fields =");

         // returns the array of Field objects representing the public fields
         Field f[] = cls.getFields();
         for (int i = 0; i < f.length; i++) {
            System.out.println(f[i]);
         }
      } catch (Exception e) {
         System.out.println("Exception: " + e);
      }
   }
} 

Output

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

Fields =
public static final int java.awt.Label.LEFT
public static final int java.awt.Label.CENTER
public static final int java.awt.Label.RIGHT
public static final float java.awt.Component.TOP_ALIGNMENT
public static final float java.awt.Component.CENTER_ALIGNMENT
public static final float java.awt.Component.BOTTOM_ALIGNMENT
public static final float java.awt.Component.LEFT_ALIGNMENT
public static final float java.awt.Component.RIGHT_ALIGNMENT
public static final int java.awt.image.ImageObserver.WIDTH
public static final int java.awt.image.ImageObserver.HEIGHT
public static final int java.awt.image.ImageObserver.PROPERTIES
public static final int java.awt.image.ImageObserver.SOMEBITS
public static final int java.awt.image.ImageObserver.FRAMEBITS
public static final int java.awt.image.ImageObserver.ALLBITS
public static final int java.awt.image.ImageObserver.ERROR
public static final int java.awt.image.ImageObserver.ABORT

Getting Fields of an ArrayList Class Example

The following example shows the usage of java.lang.Class.getFields() method. In this program, we've used class of ArrayList. Using getFields(), we've retrieved all Fields and printed them. As all fields are private, no field is printed.

package com.tutorialspoint;

import java.lang.reflect.Field;
import java.util.ArrayList;

public class ClassDemo {

   public static void main(String[] args) {

      try {
         Class cls = ArrayList.class;
         System.out.println("Fields =");

         // returns the array of Field objects representing the public fields
         Field f[] = cls.getFields();
         for (int i = 0; i < f.length; i++) {
            System.out.println(f[i]);
         }
      } catch (Exception e) {
         System.out.println("Exception: " + e);
      }
   }
} 

Output

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

Fields =

Getting Fields of an Thread Class Example

The following example shows the usage of java.lang.Class.getFields() method. In this program, we've used class of Thread. Using getFields(), we've retrieved all Fields and printed them.

package com.tutorialspoint;

import java.lang.reflect.Field;

public class ClassDemo {

   public static void main(String[] args) {

      try {
         Class cls = Thread.class;
         System.out.println("Fields =");

         // returns the array of Field objects representing the public fields
         Field f[] = cls.getFields();
         for (int i = 0; i < f.length; i++) {
            System.out.println(f[i]);
         }
      } catch (Exception e) {
         System.out.println("Exception: " + e);
      }
   }
} 

Output

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

Fields =
public static final int java.lang.Thread.MIN_PRIORITY
public static final int java.lang.Thread.NORM_PRIORITY
public static final int java.lang.Thread.MAX_PRIORITY