Map的5种遍历方法--我家超超会发光

Map的5种遍历方法

[ 2018-4-23 16:00:00 | By: 我家超超会发光 ]

public static void main(String[] args) {
Map<String, Integer> tempMap = new HashMap<String, Integer>();
tempMap.put("a","12");
tempMap.put("b","34");
tempMap.put("c","56");
// JDK1.4中
// 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);
}
System.out.println("");
// JDK1.5中,应用新特性For-Each循环
// 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);
}
System.out.println("");
// 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));
}
System.out.println("11111");
// 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);
}
}
}

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