比较string、stringbuffer、stringbuilder拼接效率

public class MainTest {

public static void main(String[] args) {

long n = 30000;

System.out.println("Start... "+n);

long start1 = System.currentTimeMillis();

String s1 = new String("hello");

for (long i = 0; i < n; i++)

{

s1+="拼接字符串的时间";

}

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+"拼接字符串的时间";

}

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("拼接字符串的时间");

}

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("拼接字符串的时间");

}

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("拼接字符串的时间");

}

long end5 = System.currentTimeMillis();

long time5 = end5 -start5;

System.out.println("用StringBuilder.append拼接字符串的时间"+time5);

System.out.println("End...");

}

}

输出结果：

Start... 30000

用String+=拼接字符串的时间32800

用String=String+拼接字符串的时间30609

用String.concat拼接字符串的时间14144

用StringBuffer.append拼接字符串的时间2

用StringBuilder.append拼接字符串的时间2

End...

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2016-12-27 18:01

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