Method Class | isDefault() Method in Java - Coding

The java.lang.reflect.Method.isDefault() method is used to check whether the method of the Method object is a Default Method: or not. It returns true if method object is a default method, otherwise it will return false.

Default Method: A public non-abstract on-static method with a body declared in an interface type.

Syntax:

public boolean isDefault()

Return Value: This method returns a boolean value. It returns true if method object is a default method by JVM Specifications, else false.

Below program illustrates isDefault() method of Method class:

Example 1:

/* 
* Program Demonstrate isDefault() method  
* of Method Class. 
*/
import java.lang.reflect.Method; 
public class GFG { 
  
    // create main method 
    public static void main(String args[]) 
    { 
  
        try { 
  
            // create class object for interface Shape 
            Class c = Shape.class; 
  
            // get list of Method object 
            Method[] methods = c.getMethods(); 
  
            // print Default Methods 
            for (Method m : methods) { 
  
                // check whether the method is Default Method or not 
                if (m.isDefault()) 
                    // Print 
                    System.out.println("Method: "
                                       + m.getName() 
                                       + " is Default Method"); 
            } 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
  
    private interface Shape { 
    default int
        draw() 
        { 
            return 0; 
        } 
  
        void paint(); 
    } 
} 

Output:

Method: draw is Default Method

Example 2:

/* 
* Program Demonstrate isDefault() method  
* of Method Class. 
* This program checks all default method in Comparator interface 
*/
import java.lang.reflect.Method; 
import java.util.Comparator; 
public class Main6 { 
  
    // create main method 
    public static void main(String args[]) 
    { 
  
        try { 
  
            // create class object for Interface Comparator 
            Class c = Comparator.class; 
  
            // get list of Method object 
            Method[] methods = c.getMethods(); 
  
            System.out.println("Default Methods of Comparator Interface"); 
            for (Method method : methods) { 
                // check whether method is Default Method or not 
                if (method.isDefault()) 
                    // print Method name 
                    System.out.println(method.getName()); 
            } 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
} 

Output:

Default Methods of Comparator Interface
reversed
thenComparing
thenComparing
thenComparing
thenComparingInt
thenComparingLong
thenComparingDouble

Reference:
https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#isDefault–

Reffered: https://www.geeksforgeeks.org

Java

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