foreach笔记

结合泛型使用，不然就只能写成for(Object o : T)。

缺点是没有下标，如下面代码

public class ForeachTest {

    public static void main(String[] args) {
        String[] s = {"kobe" , "tracy" , "tim" , "shark"};

        StringBuffer sb = new StringBuffer();

        for (int i =0 ; i < s.length ; i++){
            if (i == s.length-1){
                sb.append(s[i]);
            }else {
                sb.append(s[i]);
                sb.append(",");
            }
        }
        System.out.println(sb);
    }
}

kobe,tracy,tim,shark

如果用foreach来做

public class ForeachTest {

    public static void main(String[] args) {
        String[] s = {"kobe" , "tracy" , "tim" , "shark"};

        StringBuffer sb = new StringBuffer();

        for (String str : s){
            sb.append(str);
            sb.append(","); //kobe,tracy,tim,shark, 多了一个逗号
        }
        //所以去截掉一部分
        System.out.println(sb.substring(0 , sb.length()-1)); //kobe,tracy,tim,shark

    }
}