Map和list<map>的几种遍历方法

public static void main(String[] args) {
Map<String, Object> map = new LinkedHashMap<String, 
Object>();
map.put("username","wangking");
map.put("password", "12345");
map.put("email", "12345@qq.com");
map.put("sex", "男");
//第一种 用for循环的方式
for (Map.Entry<String, Object> m :map.entrySet())  {
System.out.println(m.getKey()+"\t"+m.getValue());
}
//利用迭代 （Iterator）
Set set=map.entrySet();
Iterator iterator=set.iterator();
while(iterator.hasNext()){
Map.Entry<String, Object> enter=(Entry<String, Object>) 
iterator.next();
System.out.println(enter.getKey()+"\t"+enter.getValue());
}
//利用KeySet 迭代
Iterator it = map.keySet().iterator();
while(it.hasNext()){
String key;   
  String value;   
  key=it.next().toString();   
  value=(String) map.get(key);   
  System.out.println(key+"--"+value);   
}
//利用EnterySet迭代
Iterator i=map.entrySet().iterator();      
System.out.println( map.entrySet().size());   
String key;      
String value;   
while(i.hasNext()){   
    Map.Entry entry = (Map.Entry)i.next();      
    key=entry.getKey().toString();      
    value=entry.getValue().toString();      
    System.out.println(key+"===="+value);           
}  
System.out.println(getKeyByValue(map, "zhaokuo"));
}
public static String getKeyByValue(Map map, Object value) {
String keys="";
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Entry) it.next();
Object obj = entry.getValue();
if (obj != null && obj.equals(value)) {
keys=(String) entry.getKey();
}
 
}
return keys;
}

　　2.

Map<String,String> map=new HashMap<String,String>();
	map.put("1","hello");
	map.put("2","name");
	map.put("3","tom");
	for(String key:map.keySet()){
		System.out.println("value值为:"+map.get(key));
	}

　　3.

Map map=new HashMap();
	map.put("1","hello");
	map.put("2","name");
	map.put("3","tom");
	Object obj=new Object();
	String wa;
	obj=map.get("1");
	wa=(String) map.get("2");
	System.out.println(obj);
	System.out.println(wa);

　　List<Map>遍历方法

List<Map<String,Object>> list = new ArrayList<Map<String, Object>>();
            Map<String,Object> map1 = new HashMap<String, Object>();
            List<String> list1 = new ArrayList<String>();
            List<String> list2 = new ArrayList<String>();
            List<String> list3 = new ArrayList<String>();
            List<String> list4 = new ArrayList<String>();
            list1.add("添加的Object-->a");
            list2.add("添加的Object-->b");
            list3.add("添加的Object-->c");
            list4.add("添加的Object-->d");

            map1.put("a",list1);
            map1.put("b",list2);
            list.add(map1);

            Map<String,Object> map2 = new HashMap<String, Object>();
            map2.put("c",list3);
            map2.put("d",list4);
            list.add(map2);

            for (Map<String,Object> map:list
                 ) {
                for (String s:map.keySet()
                     ) {
                    System.out.print("key:"+s+"\t");
                    System.out.println("value:"+map.get(s));
                }
            }
            System.out.println("======================华丽的分割线=============================");
            for (int i = 0; i < list.size(); i++) {
                Map<String, Object> map = list.get(i);
                Iterator it = map.keySet().iterator();
                while (it.hasNext()) {
                    String str = (String) it.next();
                    System.out.print("key:"+str+"\t");
                    System.out.println("value:"+map.get(str));
                }
            }
            System.out.println("========================华丽的分割线================================");

            for (Map<String, Object> map : list) {
                for (Map.Entry<String, Object> m : map.entrySet()) {
                    System.out.print("key:"+m.getKey() + "    ");
                    System.out.println("value:"+m.getValue());
                }
            }

下面这个是运行结果:

key:a   value:[添加的Object-->a]
key:b   value:[添加的Object-->b]
key:c   value:[添加的Object-->c]
key:d   value:[添加的Object-->d]
======================华丽的分割线=============================
key:a   value:[添加的Object-->a]
key:b   value:[添加的Object-->b]
key:c   value:[添加的Object-->c]
key:d   value:[添加的Object-->d]
========================华丽的分割线================================
key:a    value:[添加的Object-->a]
key:b    value:[添加的Object-->b]
key:c    value:[添加的Object-->c]
key:d    value:[添加的Object-->d]