Accessed from within inner Class

Question

I am very new to Android programming and have a little problem.

The Error is:

Variable 'Demo_Button' is accessed from within inner class. Needs to declared final.

What i tried:

changed Demo_button.setImageResource(R.drawable.pressed); to final Demo_button.setImageResource(R.drawable.pressed);

package com.iklikla.eightgame;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.ImageButton;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ImageButton Demo_button = (ImageButton)findViewById(R.id.imageButton);

    Demo_button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Demo_button.setImageResource(R.drawable.pressed);
        }
    });
}

}

Answer 1

A couple options here

First, I would declare it as a member variable then it will work

public class MainActivity extends Activity {

    ImageButton Demo_button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Demo_button = (ImageButton)findViewById(R.id.imageButton);

Second, since you are changing the View being clicked you can access it that way

emo_button.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {

    ImageButton btn = (ImageButton)v; // cast the View to an ImageButton
        btn.setImageResource(R.drawable.pressed);
    }
});

Not related but will give you an error at runtime with the current code, you need to inflate a layout before trying to initialize that Button (most likely with setContentView()). So using my first example it would look something like

public class MainActivity extends Activity {

    ImageButton Demo_button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.my_layout);  // where my_layout is the name of your layout
                                             // file containing the Button without the xml extension
       Demo_button = (ImageButton)findViewById(R.id.imageButton);