String 和StringBuffer和StringBuilder区别

1.与StringBuffer的区别:StringBuffer是线程安全的，StringBuider是线程不安全的

2. StringBuider的性能最快StringBuffer较为次之，String最慢。

3.StringBuider和StringBuffer是可变的字符序列

package ch3;

public class StringText1 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		StringBuffer str =new StringBuffer("你好吗！");
		str.append("你也好吗？");
		System.out.println(str);
		
		
		long begin =System.nanoTime();
		String s = "";
		for(int i=0; i<=5000;i++)
		{
			s += i;
		}
		long end = System.nanoTime();
		System.out.println("String time:"+(end-begin));
		
		begin = System.nanoTime();
		StringBuffer sBuffer = new StringBuffer("");
		for(int i=0; i<=5000;i++)
		{
			sBuffer.append(i);
		}
		end = System.nanoTime();
		System.out.println("StringBuffer time:"+(end-begin));
		
		begin = System.nanoTime();
		StringBuilder sBuilder= new StringBuilder("");
		for(int i=0; i<=5000;i++)
		{
			sBuilder.append(i);
		}
		end = System.nanoTime();
		System.out.println("StringBuilder time:"+(end-begin));
		
		
	}

}

结果：你好吗！你也好吗？
String time:52306271
StringBuffer time:836000
StringBuilder time:432754