Java++：Json数组形式的字符串转为Map数组 Map集合的几种遍历方式

Posted 2020-12-10 coding++

// Json数组形式的字符串转为Map数组
 
String strArr = "[{"name": "xx", "age": "16"},{"name": "yy", "age": "18"}]";
    //第一种方式
    List<Map<String,String>> listObjectFir = (List<Map<String,String>>) JSONArray.parse(strArr);
    System.out.println("利用JSONArray中的parse方法来解析json数组字符串");
    for(Map<String,String> mapList : listObjectFir){
        for (Map.Entry entry : mapList.entrySet()){
           System.out.println( entry.getKey()  + "  " +entry.getValue());
        }
    }
    //第二种方式
    List<Map<String,String>> listObjectSec = JSONArray.parseObject(strArr,List.class);
    System.out.println("利用JSONArray中的parseObject方法并指定返回类型来解析json数组字符串");
    for(Map<String,String> mapList : listObjectSec){
        for (Map.Entry entry : mapList.entrySet()){
            System.out.println( entry.getKey()  + "  " +entry.getValue());
        }
    }
    //第三种方式
    JSONArray listObjectThir = JSONArray.parseArray(strArr);
    System.out.println("利用JSONArray中的parseArray方法来解析json数组字符串");
    for(Object mapList : listObjectThir){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
    //第四种方式
    List listObjectFour = JSONArray.parseArray(strArr,Map.class);
    System.out.println("利用JSONArray中的parseArray方法并指定返回类型来解析json数组字符串");
    for(Object mapList : listObjectFour){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
    //第五种方式
    JSONArray listObjectFifth = JSONObject.parseArray(strArr);
    System.out.println("利用JSONObject中的parseArray方法来解析json数组字符串");
    for(Object mapList : listObjectFifth){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
    //第六种方式
    List listObjectSix = JSONObject.parseArray(strArr,Map.class);
    System.out.println("利用JSONObject中的parseArray方法并指定返回类型来解析json数组字符串");
    for(Object mapList : listObjectSix){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
    //第七种方式
    JSONArray listObjectSeven = JSON.parseArray(strArr);
    System.out.println("利用JSON中的parseArray方法来解析json数组字符串");
    for(Object mapList : listObjectSeven){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
    //第八种方式
    List listObjectEigh = JSONObject.parseArray(strArr,Map.class);
    System.out.println("利用JSON中的parseArray方法并指定返回类型来解析json数组字符串");
    for(Object mapList : listObjectEigh){
        for (Object entry : ((Map)mapList).entrySet()){
            System.out.println(((Map.Entry)entry).getKey()  + "  " +((Map.Entry)entry).getValue());
        }
    }
 
// map集合遍历
 Map<String, Integer> tempMap = new HashMap<String, Integer>();
  tempMap.put("a","12");
  tempMap.put("b","34");
  tempMap.put("c","56");
 
  // 遍历方法一 hashmap entrySet() 遍历
  Iterator it = tempMap.entrySet().iterator();
  while (it.hasNext()) {
   Map.Entry entry = (Map.Entry) it.next();
   Object key = entry.getKey();
   Object value = entry.getValue();
   System.out.println("key=" + key + " value=" + value);
  }
 
 
  // 遍历方法二
  for (Map.Entry<String, Integer> entry : tempMap.entrySet()) {
   String key = entry.getKey().toString();
   String value = entry.getValue().toString();
   System.out.println("key=" + key + " value=" + value);
  }
 
 
  // 遍历方法三 hashmap keySet() 遍历
  for (Iterator i = tempMap.keySet().iterator(); i.hasNext();) {
   Object obj = i.next();
   System.out.println(obj);// 循环输出key
   System.out.println("key=" + obj + " value=" + tempMap.get(obj));
  }
  for (Iterator i = tempMap.values().iterator(); i.hasNext();) {
   Object obj = i.next();
   System.out.println(obj);// 循环输出value
  }
 
  // 遍历方法四 treemap keySet()遍历
  for (Object o : tempMap.keySet()) {
   System.out.println("key=" + o + " value=" + tempMap.get(o));
  }
 
 
  // java如何遍历Map <String, ArrayList> map = new HashMap <String,
  // ArrayList>();
  System.out.println("java  遍历Map <String, ArrayList> map = new HashMap<String, ArrayList>();");
  Map<String, ArrayList> map = new HashMap<String, ArrayList>();
  Set<String> keys = map.keySet();
  Iterator<String> iterator = keys.iterator();
  while (iterator.hasNext()) {
   String key = iterator.next();
   ArrayList arrayList = map.get(key);
   for (Object o : arrayList) {
    System.out.println(o);
   }
  }
 
  Map<String, List> map = new HashMap<String, List>();
  for (Map.Entry entry : map.entrySet()) {
   String key = entry.getKey().toString();
   List<String> list= (List) entry.getValue();
   for (String value : list) {
    System.out.println(key + "====" + value);
   }
  }