五种拼字条串方法

引用：http://www.cnblogs.com/focusj/archive/2011/02/16/2057630.html

package test;

import org.apache.commons.lang.StringUtils;

public class CutString {

    //性能最差

    public String testPlus() {

        String s = "";

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

            s = s + String.valueOf(i);

        }

        return s;

    }

    //较好

    public String testConcat() {

        String s = "";

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

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

        }

        return s;

    }

     

    //性能与testStringBuffer相差无几，比其要好

    public String testJoin() {

        String[] list = new String[10000];

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

            list[i] = String.valueOf(i);

        }

        return StringUtils.join(list, "");

    }

    public String testStringBuffer() {

        StringBuffer sb = new StringBuffer();

        long l1 = System.currentTimeMillis();

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

            sb.append(String.valueOf(i));

        }

        long l2 = System.currentTimeMillis();

        System.out.println(l2-l1);

        return sb.toString();

    }

     

    //性能最高的方法

    public void testStringBuilder() {

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < 100000; i++) {

            sb.append(String.valueOf(i));

        }

        sb.toString();

    }

    public static void main(String[] args) {

        System.out.println(new CutString().testStringBuffer());

    }

}