map的遍历

最新推荐文章于 2025-03-27 10:18:00 发布

转载最新推荐文章于 2025-03-27 10:18:00 发布 · 88 阅读

CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/nhz-M/p/7508658.html

方法一：通过键值key寻找（实测效率很低，慢了一倍多的时间）

Map<Integer, Integer> map = new HashMap<Integer, Integer>();  
  
for (Integer key : map.keySet()) {  
  
    Integer value = map.get(key);  
  
    System.out.println("Key = " + key + ", Value = " + value);  
  
}

方法二：通过Iterator来遍历
　　1>使用泛型

Map<Integer, Integer> map = new HashMap<Integer, Integer>();  
  
Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator();  
  
while (entries.hasNext()) {  
  
    Map.Entry<Integer, Integer> entry = entries.next();  
  
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());  
  
}

　　2>不使用泛型

Map map = new HashMap();  
  
Iterator entries = map.entrySet().iterator();  
  
while (entries.hasNext()) {  
  
    Map.Entry entry = (Map.Entry) entries.next();  
  
    Integer key = (Integer)entry.getKey();  
  
    Integer value = (Integer)entry.getValue();  
  
    System.out.println("Key = " + key + ", Value = " + value);  
  
}

优点：你可以在遍历时调用iterator.remove()来删除entries

方法三：for-each 遍历

Map<Integer, Integer> map = new HashMap<Integer, Integer>();  
  
//遍历map中的键  
  
for (Integer key : map.keySet()) {  
  
    System.out.println("Key = " + key);  
  
}  
  
//遍历map中的值  
  
for (Integer value : map.values()) {  
  
    System.out.println("Value = " + value);  
  
}

方法四：for-each循环中使用entries

Map<Integer, Integer> map = new HashMap<Integer, Integer>();  
  
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {  
  
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());  
  
}

*******************

    Map<String,List<NewNet>> map = ipCheckService.getSegments();
    Iterator <Map.Entry<String,List<NewNet>>> entries  = map.entrySet().iterator();
    while(entries.hasNext()){
        Map.Entry<String,List<NewNet>> entry = entries.next();  
        List<NewNet> nn = entry.getValue();
        for(NewNet n:nn){
            sb.append("{\"seg\":\"").append(n.getText()).append("\",\"status\":\"").append(entry.getKey()).append("\"},");
        }
    }

转载于:https://www.cnblogs.com/nhz-M/p/7508658.html