java 之 map获取key和value

Map获取key和value

public class Test {  
  
    public static void main(String[] args) {  
        Map<String,String> map = new HashMap<String,String>();  
        map.put("b","4");  
        map.put("a","5");  
        map.put("c","3");  
        map.put("d","5");  
          
        //通过map.keySet()方法  
        //方法一：通过得到key的值，然后获取value;  
        /*for(String key : map.keySet()){ 
            String value = map.get(key); 
            System.out.println(key+"  "+value); 
        }*/  
        //使用迭代器，获取key;  
        /*Iterator<String> iter = map.keySet().iterator(); 
        while(iter.hasNext()){ 
            String key=iter.next(); 
            String value = map.get(key); 
            System.out.println(key+" "+value); 
        }*/  
        //通过map.entrySet()方法  
        //方法一：循环map里面的每一对键值对，然后获取key和value  
        /*for(Entry<String, String> vo : map.entrySet()){ 
            vo.getKey(); 
            vo.getValue(); 
            System.out.println(vo.getKey()+"  "+vo.getValue()); 
        }*/  
          
        /*//使用迭代器，获取key 
        Iterator<Entry<String,String>> iter = map.entrySet().iterator(); 
        while(iter.hasNext()){ 
            Entry<String,String> entry = iter.next(); 
            String key = entry.getKey(); 
            String value = entry.getValue(); 
            System.out.println(key+" "+value); 
        }*/  
          
        //将map<String,String> 转化为ArryList,但list里面的元素为Entry<String,String>  
        List<Entry<String,String>> list = new ArrayList<Map.Entry<String,String>>(map.entrySet());  
        Collections.sort(list,new Comparator<Entry<String,String>>(){  
            @Override  
            public int compare(Entry<String, String> o1,  
                    Entry<String, String> o2) {  
                int flag = o1.getValue().compareTo(o2.getValue());  
                if(flag==0){  
                    return o1.getKey().compareTo(o2.getKey());  
                }  
                return flag;  
            }  
        });  
        //遍历list得到map里面排序后的元素  
        for(Entry<String, String> en : list){  
            System.out.println(en.getKey()+" "+en.getValue());  
        }  
          
    }  
  
}