// interfaces/PrivateInterfaceMethods.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// {NewFeature} Since JDK 9

interface Old {

default void fd() {

System.out.println("Old::fd()");

}

static void fs() {

System.out.println("Old::fs()");

}

default void f() {

fd();

}

static void g() {

fs();

}

}

class ImplOld implements Old {}

interface JDK9 {

private void fd() { // Automatically default

System.out.println("JDK9::fd()");

}

private static void fs() {

System.out.println("JDK9::fs()");

}

default void f() {

fd();

}

static void g() {

fs();

}

}

class ImplJDK9 implements JDK9 {}

public class PrivateInterfaceMethods {

public static void main(String[] args) {

new ImplOld().f();

Old.g();

new ImplJDK9().f();

JDK9.g();

}

}

/* Output:

Old::fd()

Old::fs()

JDK9::fd()

JDK9::fs()

*/