Importance of return type in Java?

A return statement causes the program control to transfer back to the caller of a method. Every method in Java is declared with a return type and it is mandatory for all java methods. A return type may be a primitive type like int, float, double, a reference type or void type(returns nothing).

There are a few important things to understand about returning the values

• The type of data returned by a method must be compatible with the return type specified by the method. For instance, if the return type of some method is boolean, we can not return an integer.
• The variable receiving the value returned by a method must also be compatible with the return type specified for the method.
• The parameters can be passed in a sequence and they must be accepted by the method in the same sequence.

Example1

public class ReturnTypeTest1 {
   public int add() { // without arguments
      int x = 30;
      int y = 70;
      int z = x+y;
      return z;
   }
   public static void main(String args[]) {
      ReturnTypeTest1 test = new ReturnTypeTest1();
      int add = test.add();
      System.out.println("The sum of x and y is: " + add);
   }
}

Output

The sum of x and y is: 100

Example2

public class ReturnTypeTest2 {
   public int add(int x, int y) { // with arguments
      int z = x+y;
      return z;
   }
   public static void main(String args[]) {
      ReturnTypeTest2 test = new ReturnTypeTest2();
      int add = test.add(10, 20);
      System.out.println("The sum of x and y is: " + add);
   }
}

Output

The sum of x and y is: 30