This source code example demonstrates the usage of the Java method reference to an instance method of an object.
Well, a Java method reference to an instance method of an object is a type of method reference introduced in Java 8.
Method reference is used to refer method of the functional interface. It is a compact and easy form of a lambda expression.
If you have a lambda expression that refers to the instance method of an object then you can replace it with a method reference.
Syntax :
containingObject::instanceMethodName
Java method reference to an instance method of an object example
In this below example, we are using method reference to call MethodReferencesDemo class object method:
package com.java.lambda.methodref;
@FunctionalInterface
interface Printable{
void print(String msg);
}
public class MethodReferencesDemo {
public void display(String msg){
msg = msg.toUpperCase();
System.out.println(msg);
}
public static int addition(int a, int b){
return ( a + b);
}
public static void main(String[] args) {
// 2. Method reference to an instance method of an object
MethodReferencesDemo methodReferencesDemo = new MethodReferencesDemo();
// lambda expression
Printable printable = (msg) -> methodReferencesDemo.display(msg);
printable.print("hello world!");
// using method reference
Printable printableMethodRef = methodReferencesDemo::display;
printableMethodRef.print(" hello world!");
}
}
Output:
HELLO WORLD!
HELLO WORLD!
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