Question

I have a class that I borrowed from here that loads and image from a URL. I am trying to use the class by calling it from a onClickListener (if that makes sense) But I am not sure how to call the class and show the results. Right now I am just working with a static URL but eventually I it will be dynamic.

OnclickListerner in MainActivity Java:

list.setOnItemClickListener(new OnItemClickListener() {

    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3){
        showImage go = new showImage();
    }

});

and this is my showImage class:

package com.flash_tattoo;

public class showImage extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fullimage);

        ImageView imgView =(ImageView)findViewById(R.id.ImageView01);
        String url = null;
        Drawable drawable = LoadImageFromWebOperations("http://www.androidpeople.com/wp-content/uploads/2010/03/android.png");
        imgView.setImageDrawable(drawable);

    }

    private Drawable LoadImageFromWebOperations(String url) {
        try {
            InputStream is = (InputStream) new URL(url).getContent();
            Drawable d = Drawable.createFromStream(is, "src name");
            return d;
        } catch (Exception e) {
            System.out.println("Exc="+e);
            return null;
        }
    }
}

Do I need to call a new layout and then attach my showImage object to it? Any help would be great. Thanks in Advance.

Answer 1

First point, Java naming conventions have class names capitalised, this allows anybody reading the code to instantly know what’s what. Please rename the showImage class.

Secondly, this will cause a long running operation to happen in the UI thread, this is best done with an AsyncTask – see this article on Painless Threading – or a new Thread with a Handler. Long running operations on the UI thread will block any input handler events from being processed in a timely fashion and could cause your application to become unresponsive, especially with a slow mobile connection. Consider adding a progress bar or some method of letting the user know that the application is still doing something while they wait.

To answer the original question, it looks like showImage is an Activity. This means that inside the listener you don’t need to create a new showImage object, but rather fire off an Intent to view that Activity. Assuming you have the correct layout files I don’t see anything that won’t work here.

You also seem to have an unused variable, String url = null; is not needed.

Edit: You also shouldn’t really be using System.out.println(), although it will have the desired results. The standard method of logging in Android is to use the LogCat system.

As suri has mentioned, it’s also not necessary to have an entire new Activity to show your image. If you move the showImage class functions into your first Activity and add an ImageView to the first layout, you can load the image in the same Activity as the button.