如何序列化 object 它的方法有多个参数

Question

I'm a beginner to java and I need help. I have two classes, one (Song) see code is a Child of the second one (Date). Song is serializeable while Date is not serializeable (and i intend to keep the Date class that way). I'm using method from Date called setDate, it take three parameters, month, day and year, all integers. I'm trying to use custom serialization (using readObject and writeObject methods and such).

package assignment7;

import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
*
* @author Owner
*/
public class Song extends Date implements Serializable{


 private String title;
 private String artist;
 private String genre;
 //private String dateOpened;
 //private Date obj = new Date();

 public Song(){

 }
 public void setTitle(String t) {
    title = t;
 }

public void setArtist(String a) {
    artist = a;
}

public void setGenre(String g) {
    genre = g;
}

public void setDateOpen(int m, int d, int y){  
    setDate(m, d, y);
}

public void setDayOpen(){

}

public void setDayOpen(){
Date
}

public void setDayOpen(){

}

public String getDateOpen(){
   return getDate();
}

public String getTitle() {
    return title;
}

public String getArtist() {
    return artist;
}

public String getGenre() {
    return genre;
}

private void writeObject( ObjectOutputStream out ) throws IOException, ClassNotFoundException, NotSerializableException {
    out.defaultWriteObject();

      out.writeObject(getTitle());
      out.writeObject(getArtist());
      out.writeObject(getGenre());
      out.writeObject(getDateOpen());

}

private void readObject( ObjectInputStream in ) throws IOException, NotSerializableException, ClassNotFoundException {
      in.defaultReadObject();

      setTitle((String)in.readObject());
      setArtist((String)in.readObject());
      setGenre((String)in.readObject());
      setDateOpen((int)in.readObject(), (int)in.readObject(), (int)in.readObject());

}

}

The problem is that the getDateOpen method returns a string, while setDateOpen requires 3 ints. is there a way to to have readObjects() read 3 ints and still output a serialized string? (iv'e also included the date class which my teach said not to change)

package assignment7;

import java.util.Scanner;

public class Date
{
private int month;
private int day;
private int year;

public Date() { month = 0; day = 0; year = 0; }
public Date( int m, int d, int y )
{
month = editMonth( m );
day = editDay( d );
year = editYear( y );
}
public void setDate( int m, int d, int y )
{
month = editMonth( m );
day = editDay( d );
year = editYear( y );
}
public String getDate( )
{
return month + "/" + day + "/" + year;
}
public int getMonth() { return month; }
public int getDay() { return day; }
public int getYear() { return year; }

protected int editMonth( int m )
{
if( m >= 1 && m <= 12 )
  return m;
else
{
  Scanner input = new Scanner( System.in );
  while( !( m >= 1 && m <= 12 ) )
  {
    System.out.print( "Month must be 1-12 --- Please re-enter: " );
    m = input.nextInt();
  }
  return m;
  }          
  }

 protected int editDay( int d )
 {
 int [] monthDays = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

 if( d >= 1 && d <= monthDays[month - 1] )
  return d;
 else
 {
  Scanner input = new Scanner( System.in );
  while( !( d >= 1 && d <= monthDays[month - 1] ) )
  {
    System.out.print( "Day must be 1 - " + monthDays[month - 1] + " --- 
  please re-enter: " );
    d = input.nextInt();
  }
  return d;
  }
  }

 protected int editYear( int y )
 {
 if( y >= 1 )
  return y;
 else
 {
  Scanner input = new Scanner(System.in);
  while( y < 1 )
  {
    System.out.print( "Year must be greater than 1 --- please re-enter: " 
   );
    y = input.nextInt();
  }
  return y;
  }
  }
 }

Answer 1

If the Date type only offers a String date, then you'll need to pass that at some point. Either parsing in the writeObject and storing int s, or keeping with the String is the serial form and parsing in readObject .

Date only offering a stringified date probably isn't a good design choice. Also there is no way a Song should be a subtype of Date (unless there's some critical performance issue, which seems unlikely).

Also avoid Java Serialization. JSON seems the usual alternative.