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)]);