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