java是一种可以撰写跨平台应用软件的面向对象的程序设计语言，是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台（即JavaEE, JavaME, JavaSE）的总称。本站提供基于Java框架struts,spring,hibernate等的桌面应用、web交互及移动终端的开发技巧与资料

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stackoverflow

实例说明：

HashMap

1public class Test {
    public static void main(String[] args){
        Map<String,String> hashmap = new HashMap<String,String>();
        hashmap.put("name","range");
        hashmap.put("age","25");
        hashmap.put("sex","female");
        hashmap.put("nationality","PR China");
        hashmap.put("education","MD");
        hashmap.put(null,null);
        hashmap.put(null,"test");
        hashmap.put("test",null);
        Set<Map.Entry<String,String>> entryset = hashmap.entrySet();
        for(Map.Entry<String,String> each : entryset){
            System.out.println(each.getKey()+":"+each.getValue());
        }
    }
}

输出结果：

1null:test
education:MD
nationality:PR China
test:null
sex:female
name:range
age:25

TreeMap

1public class Test {
    public static void main(String[] args){
        Map<String,String> hashmap = new TreeMap<String,String>();
        hashmap.put("name","range");
        hashmap.put("age","25");
        hashmap.put("sex","female");
        hashmap.put("nationality","PR China");
        hashmap.put("education","MD");
//        hashmap.put(null,null);
//        hashmap.put(null,"test");
        hashmap.put("test",null);
        Set<Map.Entry<String,String>> entryset = hashmap.entrySet();
        for(Map.Entry<String,String> each : entryset){
            System.out.println(each.getKey()+":"+each.getValue());
        }
    }
}

输出结果：

1age:25
education:MD
name:range
nationality:PR China
sex:female
test:null

LinkedHashMap

1public class Test {
    public static void main(String[] args){
        Map<String,String> hashmap = new LinkedHashMap<String,String>();
        hashmap.put("name","range");
        hashmap.put("age","25");
        hashmap.put("sex","female");
        hashmap.put("nationality","PR China");
        hashmap.put("education","MD");
        hashmap.put(null,null);
        hashmap.put(null,"test");
        hashmap.put("test",null);
        Set<Map.Entry<String,String>> entryset = hashmap.entrySet();
        for(Map.Entry<String,String> each : entryset){
            System.out.println(each.getKey()+":"+each.getValue());
        }
    }
}

输出结果：

1name:range
age:25
sex:female
nationality:PR China
education:MD
null:test
test:null

hashmaphashtablestackoverflowjava

因为水平有限，难免有疏忽或者不准确的地方，希望大家能够直接指出来，我会及时改正。一切为了知识的分享。

后续会有更多的精彩的内容分享给大家。