list类型for遍历

package cn.stat.p9.map.demo;

import java.util.ArrayList;

public class Listfor {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ArrayList<String> al=new ArrayList<String>();
        al.add("asdf");
        al.add("qwer");
        al.add("zxcv");
        al.add("yuio");

        for(String s : al)
        {
            System.out.println(s);
        }

    }

}

foreach语句格式

for(类型 变量 ：Collection集合或数组

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//foreach 遍历map集合，要先转成单列的set
        Map<Integer,String> al=new TreeMap<Integer,String>();
        al.put(12,"asdf");
        al.put(32,"qwer");
        al.put(65,"zxcv");
        al.put(10,"yuio");

        for(Integer key : al.keySet())
        {
            String value=al.get(key);
            System.out.println("key="+value);
        }

        for(Map.Entry<Integer, String> me : al.entrySet())
        {
            Integer key =me.getKey();
            String value=me.getValue();
            System.out.println(key+" "+value);

        }