Need help displaying randomly chosen image on activity load and button press

Question

I'm trying to just make an activity that simply loads a random image when it's loaded. It compiles fine and loads fine. But simply doesn't work. Any ideas what i'm doing wrong? It's making my eyes bleed.

------------Here my RandomImage Class --------------------------------------

package com.package.name; 

import java.util.Random; 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.ImageView; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.view.View.OnClickListener; 

public class RandomImage extends Activity implements OnClickListener{ 
    private static final Random rgenerator = new Random(); 
    Integer [] mImageIds = { 
            R.drawable.pictureone, 
            R.drawable.picturetwo, 
            R.drawable.picturethree, 
            }; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.randomimage); 
    Integer q = mImageIds[rgenerator.nextInt(mImageIds.length)]; 
    ImageView iv = (ImageView) findViewById(R.id.imageviewyeah); 
    iv.setTag(q); 
    View nextButton = findViewById(R.id.next_image_button); 
    nextButton.setOnClickListener(this); 
} 

    @Override 
    public void onClick(View v) { 
    switch (v.getId()) { 
    case R.id.next_image_button: 
        Intent i = new Intent(this, RandomImage.class); 
        startActivity(i); 
        break; 
    } 
} 

    @Override 
        public boolean onCreateOptionsMenu (Menu menu) { 
                super.onCreateOptionsMenu(menu); 
                MenuInflater inflater = getMenuInflater(); 
                inflater.inflate(R.menu.menu3, menu); 
                return true; 
        } 
@Override 
public boolean onOptionsItemSelected (MenuItem item) { 
                switch (item.getItemId()) { 
                case R.id.menu: 
                        startActivity(new Intent(this, Main.class)); 
                        return true; 
} 

return false; 
        } 
}

------------Here my layout --------------------------------------

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
    android:orientation="vertical" 
xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@+id/widget0" 
android:background="@drawable/nhiebg" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
    android:layout_gravity="center" > 
<ImageView 
        android:id="@+id/imageviewyeah" 
        android:tag="q" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_gravity="center"> 
</ImageView> 
<Button 
        android:id="@+id/next_image_button" 
        android:text="Next Image" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:padding="10dip" 
        android:typeface="serif"/> 
</LinearLayout>

---

Thanks you've been a huge help, well i tried what you said. But, it just loads a random image on start, the button just does nothing. I press it then the image that was up goes away and nothing loads in its place. A whole bunch of stuff goes thru logcat, but here's the first two lines

07-17 04:15:33.102: WARN/ResourceType(30476): No package identifier when getting value for resource number 0x00000002 07-17 04:15:33.112: WARN/ImageView(30476): Unable to find resource: 2

----------------------------WHAT I HAVE NOW----------------------------

public class RandomImage extends Activity implements OnClickListener{


    private Integer [] mImageIds = { 
            R.drawable.one, 
            R.drawable.two, 
            R.drawable.three, 
            };
    private static final Random rgenerator = new Random();

    private ImageView iv;



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.randomimage);


    Integer q = mImageIds[rgenerator.nextInt(mImageIds.length)];

    iv = (ImageView) findViewById(R.id.imageviewyeah);
    iv.setImageResource(q);


    View nextButton = findViewById(R.id.next_image_button);
    nextButton.setOnClickListener(this);

}


    @Override
    public void onClick(View v) {
    switch (v.getId()) {
    case R.id.next_image_button:
        iv.setImageResource(rgenerator.nextInt(mImageIds.length));
        break;
    }

}

I'd also like to point out, i tried removing the lines

Integer q = mImageIds[rgenerator.nextInt(mImageIds.length)];

and the line

and iv.setImageResource(q);

and it still didn't work

Answer 1

Instead of iv.setTag(q), try using iv.setImageResource(q).

Additional improvements:

Your current method works in the sense that it displays a new random image, but it also ends up needlessly creating a new RandomImage activity, which can eat up memory and processing power (every time the button is pressed).

Here is a more efficient way; declare iv as an instance variable of your activity:

private ImageView iv;

and instantiate it in your onCreate() (just remove "ImageView"):

iv = (ImageView) findViewById(R.id.imageviewyeah);

This means you only have to set it once during your activity. Then, in onClick(), replace

Intent i = new Intent(this, RandomImage.class); 
startActivity(i); 
break; 

with

iv.setImageResource(mImageIds[rgenerator.nextInt(mImageIds.length)]);