testinstanceof.java

来自「Java the UML Way 书中所有源码」· Java 代码 · 共 49 行

/*
 * TestInstanceof.java   E.L. 2001-08-18
 */

abstract class A {
  public abstract void method1();
}

class C extends A {
  public void method1() {
    System.out.println("C: method1");
  }
}

abstract class B extends A {
  public void method1() {
    System.out.println("B: method1");
  }
  abstract void method2();
}

class E extends B {
  public void method2() {
    System.out.println("E: method2");
  }
}

class TestInstanceof {
  public static void main(String[] args) {
    A object1 = new C();
    A object2 = new E();
    object1.method1();
    object2.method1();
    if (object1 instanceof B) {
      B anObject = (B) object1;
      anObject.method2();
    }
    if (object2 instanceof B) {
      B anObject = (B) object2;
      anObject.method2();
    }
  }
}

/* Example Run:
C: method1
B: method1
E: method2
*/