java拼接字符串 判断内容_java--字符串拼接比较

/**

* 字符串拼接

*/

public class StringAddDemo {

public static void main(String[] args){

testStringAdd();

testConcat();

testStringBuilder();

testStringBuffer();

//+:676

//concat:243

//StringBuilder:9

//StringBuffer:1

}

public static void testStringAdd(){

String s = "";

long begin = System.currentTimeMillis();

for (int i = 0; i < 10000; i++) {

s = s + i;

}

long end = System.currentTimeMillis();

System.out.println("+:" + (end-begin));

}

//连接

public static void testConcat(){

String s = "";

long begin = System.currentTimeMillis();

for (int i = 0; i < 10000; i++) {

s = s.concat(String.valueOf(i));

}

long end = System.currentTimeMillis();

System.out.println("concat:" + (end-begin));

}

//synchronization

public static void testStringBuffer(){

StringBuffer sb = new StringBuffer();

long begin = System.currentTimeMillis();

for (int i = 0; i < 10000; i++) {

sb.append(i);

}

sb.toString();

long end = System.currentTimeMillis();

System.out.println("StringBuffer:" + (end-begin));

}

public static void testStringBuilder(){

StringBuilder sb = new StringBuilder();

long begin = System.currentTimeMillis();

for (int i = 0; i < 10000; i++) {

sb.append(i);

}

sb.toString();

long end = System.currentTimeMillis();

System.out.println("StringBuilder:" + (end-begin));

}

}