遍曆集合的常見的幾種方法

list遍曆 原文地址 http://www.2cto.com/kf/201207/140158.html

/**  *  */package com.svse.test;import java.util.*;/** * @author seven *  */public class ListTest {public static void main(String[] args) {List l = new ArrayList();l.add("世界你好！");l.add("上海");for (int i = 0; i < l.size(); i++) { // 普通的for迴圈取出集合中的元素System.out.print(l.get(i));}System.out.println();for (Object o : l) { // 增強for迴圈取出集合中的元素System.out.print(o);}System.out.println();for (Iterator it = l.iterator(); it.hasNext();) { // 利用迭代器取出集合中的元素System.out.print(it.next());}System.out.println();Iterator it = l.iterator(); // 利用迭代器取出集合中的元素while (it.hasNext()) {System.out.print(it.next());}}}

map遍曆

/** *  */package com.svse.test;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Set;/** * @author seven *  */public class MapTest1 {// java中遍曆MAP的幾種方法public static void main(String[] args) {Map<String, String> map = new HashMap<String, String>();map.put("userID", "1");map.put("username", "qq");map.put("passWord", "123");map.put("email", "qq@qq.com");// 第一種用for迴圈for (Map.Entry<String, String> entry : map.entrySet()) {System.out.println(entry.getKey() + "=" + entry.getValue());}// 第二種用迭代Set set = map.entrySet();Iterator i = set.iterator();while (i.hasNext()) {Map.Entry<String, String> entry1 = (Map.Entry<String, String>) i.next();System.out.println(entry1.getKey() + "=" + entry1.getValue());}// 用keySet()迭代Iterator it=map.entrySet().iterator(); while (it.hasNext()) {String key;String value;key = it.next().toString();value = map.get(key);System.out.println(key + "=" + value);}// 用entrySet()迭代String key;String value;while (it.hasNext()) {Map.Entry entry = (Map.Entry) it.next();key = entry.getKey().toString();value = entry.getValue().toString();System.out.println(key + "=" + value);}}}

/** *  */package com.svse.test;/** * @author seven * */import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Set;public class MapTest2 {public static void main(String[] args) {Map<String, String> m = new HashMap<String, String>();m.put("sa", "123");m.put("sb", "143");m.put("sc", "153");m.put("sd", "184");Set keyset = m.keySet(); // 對Map集合的迭代方法一keyset 迭代Iterator it = keyset.iterator();while (it.hasNext()) {String p = (String) it.next();System.out.println("value=" + m.get(p) + " ");}Iterator it2 = m.entrySet().iterator(); // Map集合的迭代方法二entrySet迭代String key;String value;while (it2.hasNext()) {Map.Entry entry = (Map.Entry) it2.next();key = entry.getKey().toString();value = entry.getValue().toString();System.out.println(key + "=" + value + " ");}for (Map.Entry entry : m.entrySet()) { // // Map集合的迭代方法三for迴圈迭代System.out.println(entry.getKey() + "=" + entry.getValue() + " ");}}}