java 遍历MAP的几种方法示例代码

java中遍历map的几种方法

map<string,string> map=new hashmap<string,string>();  
map.put("username", "qq");  
map.put("password", "123");  
map.put("userid", "1");  
map.put("email", "[e-mail]");  
map<string,string> map=new hashmap<string,string>(); 
map.put("username", "qq"); 
map.put("password", "123"); 
map.put("userid", "1"); 
map.put("email", "[e-mail]"); 

第一种用for循环

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

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

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

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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