Java之List和Map的几种遍历方法：

package com.example.zhangqianqian.java_project;

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

public class List_Map {
    public static void main(String[] args){
        //list
        List<String> list = new ArrayList<>();
        list.add("code1");
        list.add("code2");
        list.add("code3");

        //遍历方法1:for方法
        for(String chara : list){
            //System.out.println(chara);
        }
        for(int i = 0;i < list.size();i++){
            //System.out.println(list.get(i));
        }
        // 遍历方法2：转换成数组
        String[] strArray = new String[list.size()];
        list.toArray(strArray);
        for(int i = 0;i < strArray.length;i++){
            //System.out.println(strArray[i]);
        }
        for(String str : strArray){
            //System.out.println(str);
        }
        //遍历方法3：iterator方法
        Iterator<String> ite = list.iterator();
        while(ite.hasNext()){
            System.out.println(ite.next());
        }
        //Map
        Map<String,String> hashMap = new HashMap<String,String>();
        hashMap.put("code1","Content1");
        hashMap.put("code2","Content2");
        hashMap.put("code3","Content3");
        //遍历方法1：二次取值
        for(String key:hashMap.keySet()){
            System.out.println("HashMap 的 Key值："+key+" Value值："+hashMap.get(key));
        }
        //遍历方法2:Iterator方法
        Iterator<Map.Entry<String,String>> it = hashMap.entrySet().iterator();
        while (it.hasNext()){
            Map.Entry<String,String> entry = it.next();
            String key = entry.getKey();
            String value = entry.getValue();
            System.out.println("Key = "+key+" value = "+value);

        }
        //遍历方法3：for方法+entry(量大使用)
        for(Map.Entry<String,String> entry : hashMap.entrySet()){
            System.out.println("Key:" + entry.getKey());
            System.out.println("Vaule:" + entry.getValue());
        }
        //遍历方法4：获取values
        for(String v : hashMap.values()){
            System.out.println(v);
        }

    }
}