public class StringJoinTest {

    public static void main(String[] args) {

        int count = 10000;

        long begin, end, time;

        begin = System.currentTimeMillis();

        testString(count);

        end = System.currentTimeMillis();

        time = end - begin;

        System.out.println("拼接" + count + "次，String消耗时间：" + time + "毫秒");

        begin = System.currentTimeMillis();

        testStringBuffer(count);

        end = System.currentTimeMillis();

        time = end - begin;

        System.out.println("拼接" + count + "次，StringBuffer消耗时间：" + time + "毫秒");

        begin = System.currentTimeMillis();

        testStringBuilder(count);

        end = System.currentTimeMillis();

        time = end - begin;

        System.out.println("拼接" + count + "次，StringBuilder消耗时间：" + time + "毫秒");

    }

    private static String testStringBuilder(int count) {

        StringBuilder tem = new StringBuilder();

        for (int i = 0; i < count; i++) {

            tem.append("hello world!");

        }

        return tem.toString();

    }

    private static String testStringBuffer(int count) {

        StringBuffer tem = new StringBuffer();

        for (int i = 0; i < count; i++) {

            tem.append("hello world!");

        }

        return tem.toString();

    }

    private static String testString(int count) {

        String tem = "";

        for (int i = 0; i < count; i++) {

            tem += "hello world!";

        }

        return tem;

    }

}