java五种拼接字符串的方法

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());

	}

}