java中遍曆MAP的幾種方法

Java代碼

1. Map<String,String> map=new HashMap<String,String>();  
   
2. map.put("username",
   "qq");  
   
3. map.put("passWord",
   "123");  
   
4. map.put("userID",
   "1");  
   
5. map.put("email",
   "qq@qq.com"); 
   

Map<String,String> map=new HashMap<String,String>();map.put("username", "qq");map.put("passWord", "123");map.put("userID", "1");map.put("email", "qq@qq.com");

第一種用for迴圈
Java代碼

1. for(Map.Entry<String, String> entry:map.entrySet()){  
   
2.      System.out.println(entry.getKey()+"--->"+entry.getValue());  
   
3. } 

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

第二種用迭代
Java代碼

1. Set set = map.entrySet();       
2. Iterator i = set.iterator();       
3. while(i.hasNext()){    
   
4.      Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();  
   
5.      System.out.println(entry1.getKey()+"=="+entry1.getValue());  
   
6. } 

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代碼

1. Iterator it=map.keySet().iterator();  
2. while(it.hasNext()){  
   
3.      String key;  
4.      String value;  
5.      key=it.next().toString();  
6.      value=map.get(key);  
7.      System.out.println(key+"--"+value);  
   
8. } 

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代碼

1. Iterator it=map.entrySet().iterator();         
2. System.out.println( map.entrySet().size());  
3. String key;         
4. String value;  
5. while(it.hasNext()){  
   
6.         Map.Entry entry = (Map.Entry)it.next();         
7.         key=entry.getKey().toString();         
8.         value=entry.getValue().toString();         
9.         System.out.println(key+"===="+value);                   
   
10. }