Java splicing string efficiency speed comparison code + "", StringBuffer.append(), StringBuilder.append(), String.concat

Java splicing string speed comparison + "", StringBuffer.append(), StringBuilder.append(), String.concat

This is the test result of 100,000 cycle splicing unit: mm milliseconds   

+:691545
stringBuffer:11
stringBuilder:15
concat:338576

 This is the test result of 10,000 cycle splicing unit: mm milliseconds   

+:8852
stringBuffer:2
stringBuilder:3
concat:2277

If the number of cycles is low, the gap is not very big.
 

package com.lxw.rabbitmq;

// 对比 字符串拼接速度，效率
public class Test01 {
    public static void main(String[] args) {
        System.out.println("+:"+getStringAppjia(1000000));
        System.out.println("stringBuffer:"+getStringBuilder(1000000));
        System.out.println("stringBuilder:"+getStringBuffer(1000000));
        System.out.println("concat:"+getConcat(1000000));
    }

    // +""拼接
    public static Long getStringAppjia(int time) {
        long start = System.currentTimeMillis();
        String s = new String("沙雕卷饼王");
        for (int i = 0; i < time; i++) {
            s += "沙雕";
        }
        long end = System.currentTimeMillis();
//        System.out.println(s);
        return end - start;
    }
    // StringBuffer.append() 拼接
    public static Long getStringBuffer(int time) {
        long start = System.currentTimeMillis();
        StringBuffer sb = new StringBuffer("沙雕卷饼王");
        for (int i = 0; i < time; i++) {
            sb = sb.append("沙雕");
        }
        long end = System.currentTimeMillis();
//        System.out.println(sb);
        return end - start;
    }
    //StringBuilder.append()拼接
    public static Long getStringBuilder(int time) {
        long start = System.currentTimeMillis();
        StringBuilder sb = new StringBuilder("沙雕卷饼王");
        for (int i = 0; i < time; i++) {
            sb = sb.append("沙雕");
        }
        long end = System.currentTimeMillis();
//        System.out.println(sb);
        return end - start;
    }
    //concat()拼接
    public static Long getConcat(int time) {
        long start = System.currentTimeMillis();
        String sb = new String("沙雕卷饼王");
        for (int i = 0; i < time; i++) {
            sb = sb.concat("沙雕");
        }
        long end = System.currentTimeMillis();
//        System.out.println(sb);
        return end - start;
    }

}

+:691545
stringBuffer:11
stringBuilder:15
concat:338576