package com.test; public class FreeFile { public static void main(String[] args) { // 加号拼接 String str = ""; long start1 = System.currentTimeMillis(); for (int i = 0; i < 100000; i++) { str += "c"; } long end1 = System.currentTimeMillis(); System.out.println("加号拼接耗时:" + (end1 - start1) + "ms"); // concat拼接 str = ""; long start2 = System.currentTimeMillis(); for (int i = 0; i < 100000; i++) { str = str.concat("c"); } long end2 = System.currentTimeMillis(); System.out.println("concat拼接耗时:" + (end2 - start2) + "ms"); // StringBuilder拼接 str = ""; StringBuilder buffer = new StringBuilder(""); long start3 = System.currentTimeMillis(); for (int i = 0; i < 100000; i++) { buffer.append("c"); } long end3 = System.currentTimeMillis(); System.out.println("StringBuilder拼接耗时:" + (end3 - start3) + "ms"); // StringBuffer拼接 str = ""; StringBuffer sb = new StringBuffer(""); long start4 = System.currentTimeMillis(); for (int i = 0; i < 100000; i++) { sb.append("c"); } long end4 = System.currentTimeMillis(); System.out.println("StringBuffer拼接耗时:" + (end4 - start4) + "ms"); } }