java中List、Set、Map集合的遍歷方法總結

一.List集合遍歷

package resources.com.zhang.集合;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * @author created by Zhangdazhuang
 * @version v.0.1
 * @date 2018/10/13
 * @備註 測試
 **/
public class 遍歷List {
    /**定義一個List集合*/
    public List<String> getList(){
        List<String> list = new ArrayList<String>();
        list.add("Zhudazhuang");
        list.add("Jack Ma");
        list.add("Kobe");
        list.add("Andy Lau");
        return list;
    }

    /**遍歷list集合*/
    public void traversingList(List<String> list){
        int i=0;
        //方法一：通過下標遍歷
        for (i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
        //方法二：Iterator迭代器遍歷
        Iterator<String> itr = list.iterator();
        while(itr.hasNext()){
            String str = itr.next();
            System.out.println(str);
        }
        //方法三：foreach
        i=0;
        for (String s : list) {
            /*if (s.equals("hello")) {
                System.out.println("找到了hello了，該退出了");
                break;
            }*/
            System.out.print("第" + (++i) + "個元素" + s + ";");
        }
        System.out.println("");

    }

    public static void main(String[] args) {
        遍歷List test = new 遍歷List();
        List<String> list = test.getList();//獲得List集合
        test.traversingList(list);//遍歷List集合並輸出
    }








}

 

二.Set集合

package resources.com.zhang.集合;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 * @author created by Zhangdazhuang
 * @version v.0.1
 * @date 2018/10/13
 * @備註 測試
 **/
public class 遍歷Set {
    /**
     * 定義一個Set集合
     */
    public Set<String> getSet() {
        Set<String> set = new HashSet<String>();
        set.add("ZhuXun");
        set.add("Jack Ma");
        set.add("Kobe");
        set.add("Andy Lau");
        return set;
    }

    /**
     * 遍歷Set集合
     */
    public void traversingSet(Set<String> set) {
        //方法一：Iterator迭代器遍歷
        Iterator<String> itr = set.iterator();
        while (itr.hasNext()) {
            String str = itr.next();
            System.out.println(str);
        }

        //方法二：通過增強型for迴圈遍歷
        //注：Set集合中不存在下標，因此無法通過下標遍歷，對於Java編譯器而言，方法一和方法二是等價的
        for (String str : set) {
            System.out.println(str);
        }
    }

    public static void main(String[] args) {
        遍歷Set test = new 遍歷Set();
        Set<String> set = test.getSet();//獲得Set集合
        test.traversingSet(set);//遍歷Set集合並輸出
    }


}

 

三.Map集合遍歷

package resources.com.zhang.集合;

import java.util.HashMap;
import java.util.Map;

/**
 * @author created by Zhangdazhuang
 * @version v.0.1
 * @date 2018/10/13
 * @備註 測試
 **/
public class 遍歷Map {
    /**
     * 定義一個Map集合
     */
    public Map<String, String> getMap() {
        Map<String, String> map = new HashMap<String, String>();
        map.put("ZhuXun", "are very handsome");
        map.put("Kobe", "are very storng");
        map.put("Jack Ma", "are very clever and rich");
        map.put("Andy Lau", "are very man and charismatic");
        return map;
    }

    /**
     * 遍歷Map集合
     */
    public void traversingMap(Map<String, String> map) {
        //方法一：通過Entry遍歷<迭代Entry>
        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println(entry.getKey() + "：" + entry.getValue());
        }
        //方法二：通過Set集合遍歷<迭代Set>
        for (String key : map.keySet()) {
            System.out.println(key + "：" + map.get(key));
        }
    }

    public static void main(String[] args) {
        遍歷Map test = new 遍歷Map();
        Map<String, String> map = test.getMap();//獲得map集合
        test.traversingMap(map);//遍歷map集合並輸出
    }


}