java 继承PrintWriter方法

import java.io.PrintWriter;
import java.io.OutputStream;


class MPrintWriter extends PrintWriter
{
        public MPrintWriter(OutputStream out)
        {
                super(out);
        }
}

public class tmp
{
        public static void main(String args[]) throws Exception
        {
                MPrintWriter writer = new MPrintWriter(System.out);
                
                writer.write("hello\n");
                writer.flush();
                writer.close();
        }
}