Following is an example displaying how to use private methods in Java 9 Interfaces −
Example
interface my_int{ public abstract void multiply_vals(int a, int b); public default void add_vals(int a, int b){ sub_vals(a, b); System.out.print("Default method result "); System.out.println(a + b); } private void sub_vals(int a, int b){ System.out.print("Private method result "); System.out.println(a - b); } private static void div(int a, int b){ System.out.print(" Private static method result "); System.out.println(a / b); } } public class my_new_int implements my_int{ @Override public void multiply_vals(int a, int b){ System.out.print("Abstract method result "); System.out.println(a * b); } public static void main(String[] args){ my_int in = new my_new_int(); in.multiply_vals(11, 34); in.add_vals(78, 0); } }
Output
Abstract method result 374 Private method result 78 Default method result 78
An interface named ‘my_int’ is defined, that has an abstract function, without a body. Another default function is defined, that basically adds two numbers. Another function named ‘sub_vals’ is defined, which subtracts the two numbers.
Another static function named div is defined that divides the two values. A class named ‘my_new_int’ implements the previously defined interface. It overrides the function that multiplies values and redefines it. In the main function, an instance of the interface is created, and the ‘multiply_vals’ function is called by passing specific values. Similarly, the ‘add_vals’ function is also called by passing specific values. The respective output is displayed on the console.