Java之"instanceof"和"isInstance"代码举例

 源码：

/**
 * @Date:2018-04-20
 * @Description:判断Instance
 * - instanceof方法返回一个boolean类型的值，意在告诉我们对象是不是某个特定的类型实例。
 * - isInstance方法则是Class类中的一个Native方法，也是用于判断对象类型的。
 **/
public class InstanceDemo {

    static void test(Object x) {
        System.out.println("Testing x of type " + x.getClass());
        System.out.println("x instanceof A " + (x instanceof A));
        System.out.println("x instanceof B " + (x instanceof B));
        System.out.println("A.isInstance(x) " + A.class.isInstance(x));
        System.out.println("B.isInstance(x) " +
                B.class.isInstance(x));
        System.out.println("x.getClass() == A.class " +
                (x.getClass() == A.class));
        System.out.println("x.getClass() == B.class " +
                (x.getClass() == B.class));
        System.out.println("x.getClass().equals(A.class)) " +
                (x.getClass().equals(A.class)));
        System.out.println("x.getClass().equals(B.class)) " +
                (x.getClass().equals(B.class)));
    }

    public static void main(String[] args) {
        test(new A());
        System.out.println("-------------------------");
        test(new B());
    }

}

class A {
}

class B extends A {
}

 运行结果：

Testing x of type class org.study2.reflection.A
 x instanceof A true
 x instanceof B false
 A.isInstance(x) true
 B.isInstance(x) false
 x.getClass() == A.class true
 x.getClass() == B.class false
 x.getClass().equals(A.class)) true
 x.getClass().equals(B.class)) false
 -------------------------
 Testing x of type class org.study2.reflection.B
 x instanceof A true
 x instanceof B true
 A.isInstance(x) true
 B.isInstance(x) true
 x.getClass() == A.class false
 x.getClass() == B.class true
 x.getClass().equals(A.class)) false
 x.getClass().equals(B.class)) true