Java 拼接字符串效率速度对比 代码 +““, StringBuffer.append(),StringBuilder.append(),String.concat

Java 拼接字符串速度对比 +"", StringBuffer.append(),StringBuilder.append(),String.concat

这个是测试100000次循环拼接结果 单位:mm 毫秒   

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

 这个是测试10000次循环拼接结果 单位:mm 毫秒   

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

如果是循环次数低的话，差距也不是很大。
 

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