Java: how to make this serializable?

I need the following class to be serializable

package helpers;

public class XY implements Comparable<XY>
{
    public int x;
    public int y;

    public XY (int x,int y)
    {
        this.x = x;
        this.y = y;
    }

    public int compareTo( XY other ) 
    {
        String compare1 = this.x + "-" + this.y;
        String compare2 = other.x + "-" + other.y;

        return compare1.compareTo( compare2 );
    }

    public String toString()
    {
        return this.x + "-" + this.y;
    }

}

So far, I can't send it as an object with OutputStream I tried to implement serializable, but it didn't work

Solution

Implementing serializable will work, but you must write objects using objectoutputstream, not just OutputStream