发表于 2012-10-30 07:43:09 by 月小升
instanceof 用来判断一个对象(Object)是否为某一个类型
比如String str = “abc”. str是否为String类型
HashMap m = new HashMap m 是否为一个hashmap
instanceof常用于,知道一个Object,但是后面的代码需要判断Object的类型。
package com.javaer.examples;
import java.util.HashMap;
public class TestInstance {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String str = "abc";
HashMap m = new HashMap();
Integer a =20;
if( str instanceof java.lang.String){
System.out.println("str is a String!");
}
if( m instanceof java.util.HashMap){
System.out.println("m is a HashMap!");
}
if( a instanceof java.lang.Integer){
System.out.println("a is a Integer!");
}
}
} |
package com.javaer.examples;
import java.util.HashMap;
public class TestInstance {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String str = "abc";
HashMap m = new HashMap();
Integer a =20;
if( str instanceof java.lang.String){
System.out.println("str is a String!");
}
if( m instanceof java.util.HashMap){
System.out.println("m is a HashMap!");
}
if( a instanceof java.lang.Integer){
System.out.println("a is a Integer!");
}
}
}
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