In this tutorial, we are learning about Java interfaces and their static methods. Prior to Java 8, one would create separate class to hold the helper and utility classes. For example : Collections is a utility class that holds all the static methods to be used with List and Collection interfaces. With static methods in Java, one could simply add such methods to Java interfaces. Here is the code used in this tutorial
package com.training.java;
public interface Interviewer {
int maxInterviewPerWeek = 3;
void interview();
static void scheduleMeeting(int hrs) {
System.out.println(“Booked room for ” + hrs + “hrs”);
}
}
package com.training.java;
public class Manager implements Interviewer {
@Override
public void interview() {
System.out.println(“I am Manager, I am hiring for my team”);
}
}
package com.training.java;
public class Program {
public static void main(String[] args) {
Interviewer interviwer = new Manager();
Interviewer.scheduleMeeting(2);
interviwer.interview();
}
}
Java Interfaces vs Classes
1. Both are reference types
2. Both can contain constant, method signatures, default methods, static methods and nested types
3. Both define implementation for default methods and static methods
Interfaces cannot be instantiated, rather they can only be extended by other interfaces or implemented by classes
