Android adding Listener with resources to many buttons

Question

I have a very weird problem with my Android project. I have a 2d array of buttons and i am trying to add action listener to those. So this is what i have:

for ( i = 0; i<buttons.length;i++)
       {
           for ( k = 0; k<buttons[i].length;k++)
           {
               String but = "mtp" + i + k;
               buttons[i][k] = (Button)v.findViewWithTag(but);
               if (k%2 == 0)
               {
                   buttons[i][k].setOnClickListener(new View.OnClickListener() {
                        public void onClick(View v) {
                            text.setText(words[w]);
                            w++;
                        }
                   });
               }
               else
               {

                   buttons[i][k].setOnClickListener(new View.OnClickListener() {
                        public void onClick(View v) {
                            int res = getResources().getIdentifier(icons[p],"drawable", getPackageName());
                            buttons[i][k].setBackgroundResource(res);
                            p++;
                        }
                   });


               }
           }
       }

The weird thing is that my first action Listener works fine. It changes the TextView correctly. But the second one crashes my app. Moreover when i set an action listener not in a loop but outside of it like:

buttons[0][1].setOnClickListener(new View.OnClickListener() {
                        public void onClick(View v) {
                            int res = getResources().getIdentifier(icons[p],"drawable", getPackageName());
                            buttons[0][1].setBackgroundResource(res);
                            p++;
                        }
                   });

It works just fine. What do i do? How can i fix this?

Answer 1

Are these buttons in your XML file? Or are you trying to do it programmatically? Because you can implement the OnClickListener with your Activity.

Here's an alternative

XML:

<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="button1"
android:text="@string/button1" />

Java:

public class YOUNAMEHERE extends Activity implements OnClickListener {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}
public void button1 (View v) {
    *The things you want to happen when the button is pressed*
}

This shortens the amount of code you have to write and is easier to read since everything is implemented beforehand.

I know this doesn't really completely answer your question but I hope it helps. This is what I know so far about coding for Android with Java.

Answer 2

First of all you cannot use i and k variables in the anonymous class (inside new View.OnClickListener() implementation) until it declared as final .

Also, text variable (as reference to some TextView object as I can see) have to be final too, so, it will reference to the same TextView in every iteration.

And you have to change

buttons[i][k].setBackgroundResource(res);

with something like

((Button)view).setBackgroundResource(res);

because when the onClick() handler will be called, the i and k variables will be invalid. But the onClick() argument named view has actual reference to the view has been clicked.