java Map 怎么遍历

Posted 2020-09-12 Programming is an art

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java中遍历MAP的几种方法
Java代码
Map<String,String> map=new HashMap<String,String>();
map.put("username", "qq");
map.put("passWord", "123");
map.put("userID", "1");
map.put("email", "[email protected]");
Map<String,String> map=new HashMap<String,String>();
map.put("username", "qq");
map.put("passWord", "123");
map.put("userID", "1");
map.put("email", "[email protected]");
第一种用for循环
Java代码

for(Map.Entry<String, String> entry:map.entrySet()){
     System.out.println(entry.getKey()+"--->"+entry.getValue());
}
for(Map.Entry<String, String> entry:map.entrySet()){
          System.out.println(entry.getKey()+"--->"+entry.getValue());
}

第二种用迭代
Java代码

Set set = map.entrySet();
Iterator i = set.iterator();
while(i.hasNext()){
     Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();
     System.out.println(entry1.getKey()+"=="+entry1.getValue());
}
Set set = map.entrySet();
Iterator i = set.iterator();
while(i.hasNext()){
    Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();
    System.out.println(entry1.getKey()+"=="+entry1.getValue());
}
用keySet()迭代
Java代码

Iterator it=map.keySet().iterator();
while(it.hasNext()){
     String key;
     String value;
     key=it.next().toString();
     value=map.get(key);
     System.out.println(key+"--"+value);
}
Iterator it=map.keySet().iterator();
while(it.hasNext()){
    String key;
    String value;
    key=it.next().toString();
    value=map.get(key);
    System.out.println(key+"--"+value);
}

用entrySet()迭代
Java代码

Iterator it=map.entrySet().iterator();
System.out.println( map.entrySet().size());
String key;
String value;
while(it.hasNext()){
        Map.Entry entry = (Map.Entry)it.next();
        key=entry.getKey().toString();
        value=entry.getValue().toString();
        System.out.println(key+"===="+value);
}

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