遍历Map

测试程序如下：

1：获取键值4种：entrySet: 2种(foreach,iterator)   和  keySet+get: 2种(foreach,iterator)   

    /**
     * 获取键与值
     */
    public static void iterEntry(Map<String,Students> map){
        System.out.println("======entrySet 2种========");
        Set<Map.Entry<String, Students>> entrySet =map.entrySet();
        
        
        System.out.println("1==foreach========");
        for(Map.Entry<String, Students> temp:entrySet){
            String key =temp.getKey();
            Students value =temp.getValue();
            
            System.out.println(key+"-->"+value);
        }
        
        
        System.out.println("2==iterator========");
        Iterator<Map.Entry<String, Students>> it =entrySet.iterator();
        while(it.hasNext()){
            Map.Entry<String, Students> temp =it.next();
            String key =temp.getKey();
            Students value =temp.getValue();            
            System.out.println(key+"-->"+value);
        }
        
        
        
        System.out.println("======keySet+get 2种========");
        Set<String> keySet =map.keySet();
        System.out.println("1==foreach========");
        for(String key:keySet){
            Students value =map.get(key);
            System.out.println(key+"-->"+value);
        }
        System.out.println("2==iterator========");
        Iterator<String> keyIt =keySet.iterator();
        while(keyIt.hasNext()){
            String key =keyIt.next();
            Students value =map.get(key);
            System.out.println(key+"-->"+value);
        }
    }

 

2.获取键4种方法：entrySet: 2种(foreach,iterator)   和  keySet+get: 2种(foreach,iterator)   

 

    public static void iterKeys(Map<String,Students> map){
        System.out.println("======entrySet 2种========");
        Set<Map.Entry<String, Students>> entrySet =map.entrySet();
        System.out.println("1==foreach========");
        for(Map.Entry<String, Students> temp:entrySet){
            String key =temp.getKey();            
            System.out.println(key);
        }
        
        System.out.println("2==iterator========");
        Iterator<Map.Entry<String, Students>> it =entrySet.iterator();
        while(it.hasNext()){
            Map.Entry<String, Students> temp =it.next();
            String key =temp.getKey();        
            System.out.println(key);
        }
        System.out.println("======keySet+get 2种========");
        Set<String> keySet =map.keySet();
        System.out.println("1==foreach========");
        for(String key:keySet){
            System.out.println(key);
        }
        System.out.println("2==iterator========");
        Iterator<String> keyIt =keySet.iterator();
        while(keyIt.hasNext()){
            String key =keyIt.next();
            System.out.println(key);
        }
    }

3.获取值6种方法： entrySet 2种，keySet+get 2种，values() 2种

public static void iterValues(Map<String,Students> map){
        System.out.println("======entrySet 2种========");
        System.out.println("======keySet+get 2种========");
        System.out.println("======values() 2种========");
        Collection<Students> values =map.values();    
        
        System.out.println("1==foreach========");
        for(Students p:values){
            System.out.println(p);
        }
        System.out.println("2==iterator========");
        Iterator<Students> it =values.iterator();
        while(it.hasNext()){
            Students p =it.next();
            System.out.println(p);
        }