废话不多说,直接上代码
long n = 10000; long start1 = System.currentTimeMillis(); String s1 = new String("hello"); for (long i = 0; i < n; i++) { s1 += "拼接--"; } long end1 = System.currentTimeMillis(); long time1 = end1 - start1; System.out.println("用String+=拼接字符串的时间:" + time1); long start2 = System.currentTimeMillis(); String s2 = new String("hello"); for (long i = 0; i < n; i++) { s2 = s2 + "拼接--"; } long end2 = System.currentTimeMillis(); long time2 = end2 - start2; System.out.println("用String=String+拼接字符串的时间" + time2); long start3 = System.currentTimeMillis(); String s3 = new String("hello"); for (long i = 0; i < n; i++) { s3 = s3.concat("拼接--"); } long end3 = System.currentTimeMillis(); long time3 = end3 - start3; System.out.println("用String.concat拼接字符串的时间" + time3); long start4 = System.currentTimeMillis(); StringBuffer s4 = new StringBuffer("hello"); for (long i = 0; i < n; i++) { s4.append("拼接--"); } long end4 = System.currentTimeMillis(); long time4 = end4 - start4; System.out.println("用StringBuffer.append拼接字符串的时间" + time4); long start5 = System.currentTimeMillis(); StringBuilder s5 = new StringBuilder("hello"); for (long i = 0; i < n; i++) { s5.append("拼接--"); } long end5 = System.currentTimeMillis(); long time5 = end5 - start5; System.out.println("用StringBuilder.append拼接字符串的时间" + time5);
在Android机上的实测结果为:
06-08 22:06:23.650: I/System.out(28027): 用String+=拼接字符串的时间:3295
06-08 22:06:27.080: I/System.out(28027): 用String=String+拼接字符串的时间3429
06-08 22:06:30.280: I/System.out(28027): 用String.concat拼接字符串的时间3208
06-08 22:06:30.320: I/System.out(28027): 用StringBuffer.append拼接字符串的时间27
06-08 22:06:30.320: I/System.out(28027): 用StringBuilder.append拼接字符串的时间8
参考资料
http://niufc.iteye.com/blog/1707394