instanceof的用法

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interface A{}class B implements A{ }class C extends B{ }public class Iinstanceof {public static void main(String[] args) {A ab=new B();A ac=new C();B bc=new C();B bb=new B();C cc=new C();//对象实现一个接口，用这个对象和这个接口进行instanceof判断，都为true。System.out.println("ab instanceof A="+(ab instanceof A));System.out.println("ac instanceof A="+(ac instanceof A));System.out.println("bc instanceof A="+(bc instanceof A));System.out.println("bb instanceof A="+(bb instanceof A));System.out.println("cc instanceof A="+(cc instanceof A));//对象和父类进行instanceof判断，都为trueSystem.out.println("ab instanceof B="+(ab instanceof B));System.out.println("ac instanceof B="+(ac instanceof B));System.out.println("bc instanceof B="+(bc instanceof B));System.out.println("bb instanceof B="+(bb instanceof B));System.out.println("cc instanceof B="+(cc instanceof B));//对象和他的子类进行instanceof判断为falseSystem.out.println("ab instanceof C="+(ab instanceof C));System.out.println("ac instanceof C="+(ac instanceof C));System.out.println("bc instanceof C="+(bc instanceof C));System.out.println("bb instanceof C="+(bb instanceof C));System.out.println("cc instanceof C="+(cc instanceof C));}}

程序输出：
ab instanceof A=true
ac instanceof A=true
bc instanceof A=true
bb instanceof A=true
cc instanceof A=true
ab instanceof B=true
ac instanceof B=true
bc instanceof B=true
bb instanceof B=true
cc instanceof B=true
ab instanceof C=false
ac instanceof C=true
bc instanceof C=true
bb instanceof C=false
cc instanceof C=true

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