请说出E类中标注的【代码1】~【代码4】的输出结果。 i

import java.io.*;
public class E{
    public static void main(String args[]){
      int n=-1;
      File f=new File("hello.txt");
      byte[] a = "abcd".getBytes();
       try{
            FileOutputStream out = new FileOutputStream(f);
            out.write(a);
            out.close();
            FileInputStream in = new FileInputStream(f);
            byte[] tom = new byte[3];
            int m = in.read(tom,0,3);
            System.out.println(m);   //【代码1】
            String s=new String(tom,0,3);
            System.out.println(s);   //【代码2】
            m=in.read(tom,0,3);
            System.out.println(m);   //【代码3】
            s=new String(tom,0,3);
            System.out.println(s);   //【代码4】
         }
        catch(IOException e){}
    }
}