public class Main { public static void main(String[] args) { MyCalculator calculator = new MyCalculator(); System.out.println(calculator.multiply(1, 2)); } } class MyCalculator implements Calculator { @Override public int add(int a, int b) { return a + b; } @Override public int subtract(int a, int b) { return 0; } } interface Calculator { int add(int a, int b); int subtract(int a, int b); default int multiply(int a, int b) { return a * b; } }