Can we define default methods in functional interfaces in java 8

• Functional interfaces in java 8 will have single abstract method in it.
• Check below two pages regarding defining and using functional interfaces using Lamda expressions.
• Java 8 functional interface with example
• Implement java 8 functional interface using lambda example program
• We can define default methods in functional interfaces in java 8.
• But every functional interface must have single abstract method in it.
• As we know that default methods should have a implementation as they are not abstract methods.
• Lets see an example program on defining functional interface with default method.

#1:  Java example program to create functional interface with default method.

1. package com.instanceofjava.java8;
2. 
   
3. /**
4.  * @author www.Instanceofjava.com
5.  * @category interview programming questions
6.  * 
7.  * Description: java 8 functional interfaces
8.  *
9.  */
10. @FunctionalInterface
11. public interface FunctionalInterfaceExample {
12.  
13. void show();
14.         //default method
15. default void message() {
16. System.out.println("hello this is default method in functional interface");
17. }
18. }

#2: Java Example program on how to implement functional interface abstract method and use default method.

• Can we define multiple abstract methods in functional interface ?
• Functional interface with multiple abstract methods in java 8
• Can we define multiple default method inside a functional interface.
• Yes, We can define multiple default methods inside a functional interface