java：stringbuilder与string的转化

package 初学java;

public class stringbuilder中的tostring方法 {
	public static void main(String[] args) {
		//String--->StringBuilder
		String s="hello";
		StringBuilder s1=new StringBuilder(s);//*****
		
		//往StringBuilder中添加数据。可有可无
		s1.append(" world");
		System.out.println("StringBuilder型的s1:"+s1);
		
		
		//StringBuilder--->string
		String s2=s1.toString();
		System.out.println("String s2:"+s2);
		
	}
}