instanceof

關於instanceof關鍵字的小示例：

package com.rain.test;

/**
 * instanceof關鍵字使用簡單示例.
 */
public class InstanceofTest {

	public static void main(String[] args) {
		Dog dogFirst = null;
		System.out.println("dogFirst instanceof Dog");
		System.out.println(dogFirst instanceof Dog);
		Dog dogSecond = new Dog();
		System.out.println("dogSecond instanceof Dog");
		System.out.println(dogSecond instanceof Dog);

		// 原因猜測instanceof是
		// 1、當dogXXX對象爲null時,直接返回false
		// 2、當dogXXX對象不爲null時,的getClass()方法與目標類(Dog)的.class進行比較得出結果的
		if (dogFirst != null) {
			System.out.println("dogFirst.getClass() " + dogFirst.getClass());
		} else {
			System.out.println(false);
		}
		
		
		if (dogSecond != null) {
			System.out.println("dogSecond.getClass() " + dogSecond.getClass());
		} else {
			System.out.println(false);
		}
		System.out.println(Dog.class);
	}
}

class Dog {

}

控制檯輸出：