Map集合和List集合的幾種遍歷方式
阿新 • • 發佈:2019-02-10
- ++++++++++++++++++++++List集合遍歷++++++++++++++++++++++++++++++++++++++++++++++
- publicstaticvoid main(String[] args) {
- List<String> list=new ArrayList<String>();
- list.add("123");
- list.add("456");
- list.add("789");
- System.out.println("------經典的for迴圈-----");
- for (int i =
- System.out.println(list.get(i));
- }
- System.out.println("-------Iterate迴圈--------");
- Iterator<String> iter=list.iterator();
- while(iter.hasNext())
- {
- System.out.println(iter.next());
- }
- System.out.println("-------foreach迴圈---------"
- for (String string : list) {
- System.out.println(string);
- }
- }
- ++++++++++++++++++++++MAP集合的遍歷++++++++++++++++++++++++++++++++++++++++++++++
- //迴圈遍歷map的方法
- publicclass MapF {
- publicstaticvoid 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
- // 遍歷方法一 hashmap entrySet() 遍歷
- 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,應用新特性For-Each迴圈
- // 遍歷方法二
- 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("");
- // 遍歷方法三 hashmap keySet() 遍歷
- for (Iterator i = tempMap.keySet().iterator(); i.hasNext();) {
- Object obj = i.next();
- System.out.println(obj);// 迴圈輸出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);// 迴圈輸出value
- }
- // 遍歷方法四 treemap keySet()遍歷
- for (Object o : tempMap.keySet()) {
- System.out.println("key=" + o + " value=" + tempMap.get(o));
- }
- System.out.println("11111");
- // java如何遍歷Map <String, ArrayList> map = new HashMap <String,
- // ArrayList>();
- System.out.println("java 遍歷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);
- }
- }
- }
- }