public class Interface1 {
	public static void main(String[] args) {
		TestClass1 tco1 = new TestClass1();
		TestClass2 tco2 = new TestClass2();
		tco1.sayHello();
		tco2.sayHello();

		if (tco1 instanceof TestClass1)
			System.out.println("tco1 is instance of TestClass1");

		if (tco1 instanceof PoliteObject)
			System.out.println("tco1 is instance of PoliteObject");

		PoliteObject po;
		po = tco1;
		po.sayHello();
		po = tco2;
		po.sayHello();
	} //main()
} //class Interface1

interface PoliteObject {
	public void sayHello();
} //interface PoliteObject

class TestClass1 implements PoliteObject {
	public void sayHello() {
		System.out.println("Hello World");
	} //sayHello()
} //class TestClass1

class TestClass2 implements PoliteObject {
	public void sayHello() {
		System.out.println("Guten Tag");
	} //sayHello()
} //class TestClass2