familyvsexacttype.java

来自「中文JAVA编程思想第二版,一本很好的JAVA入门书籍!」· Java 代码 · 共 38 行

//: c12:FamilyVsExactType.java
// From 'Thinking in Java, 2nd ed.' by Bruce Eckel
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
// The difference between instanceof and class

class Base {}
class Derived extends Base {}

public class FamilyVsExactType {
  static void test(Object x) {
    System.out.println("Testing x of type " +
      x.getClass());
    System.out.println("x instanceof Base " +
      (x instanceof Base));
    System.out.println("x instanceof Derived " +
      (x instanceof Derived));
    System.out.println("Base.isInstance(x) " +
      Base.class.isInstance(x));
    System.out.println("Derived.isInstance(x) " +
      Derived.class.isInstance(x));
    System.out.println(
      "x.getClass() == Base.class " +
      (x.getClass() == Base.class));
    System.out.println(
      "x.getClass() == Derived.class " +
      (x.getClass() == Derived.class));
    System.out.println(
      "x.getClass().equals(Base.class)) " +
      (x.getClass().equals(Base.class)));
    System.out.println(
      "x.getClass().equals(Derived.class)) " +
      (x.getClass().equals(Derived.class)));
  }
  public static void main(String[] args) {
    test(new Base());
    test(new Derived());
  }
} ///:~