Question

I made a image thread class that runs the update method in the instance that is loading the image:

public class ImageThread implements Runnable {
    private Bitmap image;
    private String url;
    private CustomEventField c;


    public ImageThread(String url, CustomEventField c){

        this.url = url;
        this.c = c;
    }

   public void notifyUs(){



        this.c.update(image);
    }

    public void run() {

        Bitmap img =  downloadImage.connectServerForImage(this.url); //data processing

        image = img;

        notifyUs();

    }




}

I send the context in the constructor, however I can only use it for CustomEventField. What if I wanted to use this image class for other classes? I could just make another copy of this class, but I want to keep things organized.

Answer 1

Define a separate interface type that all of your classes can then implement as needed, eg:

ImageThreadCallback.java:

public interface ImageThreadCallback
{
    void update(Bitmap image);
}

ImageThread.java:

public class ImageThread implements Runnable
{
    private Bitmap image;
    private String url;
    private ImageThreadCallback c;

    public ImageThread(String url, ImageThreadCallback c)
    {
        this.url = url;
        this.c = c;
    }

    public void notifyUs()
    {
        this.c.update(this.image);
    }

    public void run()
    {
        this.image = downloadImage.connectServerForImage(this.url); //data processing
        notifyUs();
    }
}

CustomEventField.java:

public class CustomEventField implements ImageThreadCallback
{
    public void update(Bitmap image)
    {
        ...
    }
}

CustomEntryField.java:

public class CustomEntryField implements ImageThreadCallback
{
    public void update(Bitmap image)
    {
        ...
    }
}