Java Nested Class

A Java nested class is a class within a class. You may want to create a class within a class for data encapsulation and protect that class from calling from other classes outside.

Java Nested Class Example 1

package com.javapointers.javacore;

public class ClassA {

     public static void main(String[] args) {
          ClassB b = new ClassB();
          int ans = b.addNum(10,20);
          System.out.println(ans);
     }
}

class ClassB {
     
     public int addNum(int first, int second) {
          int answer = first + second;
          return answer;
     }
}

Java Nested Class Example 2

package com.javapointers.javacore;

public class ClassA extends ClassB{

     public static void main(String args[]){
          ClassA a = new ClassA();
          String con = a.concatString("Hello ", "Javapointers");
          System.out.println(con);
     }
}


class ClassB {

     public String concatString(String a, String b){
          String con = a.concat(b);
          return con;
     }
}

The next topic is about how to return value from a method in Java.