NullPointerException when trying to use ImageView - reflection

Question

I grabbed the following code from another site - I can't find a problem with it but it keeps giving me a nullpointerexception. The issue I think is right in the first part before the setContentView but including the whole thing just in case. Thanks in advance for the help!
public class TileSet extends Activity {
Bitmap originalImage = BitmapFactory.decodeResource(getResources(),
R.drawable.announcementbc);
ImageView imageView;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
//Create an Image view and add our bitmap with reflection to it
imageView.setImageBitmap(getRefelection(originalImage));
//imageView.setImageBitmap(image);
//Add the image to a linear layout and display it
LinearLayout linLayout = new LinearLayout(this);
linLayout.addView(imageView, new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
// set LinearLayout as ContentView
setContentView(linLayout);
}
// public static Bitmap getRefelection(Bitmap image)
public static Bitmap getRefelection(Bitmap image)
{
//The gap we want between the reflection and the original image
final int reflectionGap = 4;
//Get you bit map from drawable folder
Bitmap originalImage = image;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
//This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
//Create a Bitmap with the flip matix applied to it.
//We only want the bottom half of the image
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);
//Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width
, (height + height/2), Config.ARGB_8888);
//Create a new Canvas with the bitmap that's big enough for
//the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
//Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
//Draw in the gap
Paint deafaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);
//Draw in the reflection
canvas.drawBitmap(reflectionImage,0, height + reflectionGap, null);
//Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff,
TileMode.CLAMP);
//Set the paint to use this shader (linear gradient)
paint.setShader(shader);
//Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
//Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width,
bitmapWithReflection.getHeight() + reflectionGap, paint);
reflectionImage.recycle();
return bitmapWithReflection;
}
}

Answer 1

imageView.setImageBitmap(getRefelection(originalImage));
This is the line it is crashing on, and the reason is that imageView is null.
When you create a member variable such as the one you listed, you need to either create an object for it to point to, or set it to an already-created object.
In your case, I'm guessing you want to set it to one already created by your layout. Your layout XML should have some ImageView declared, but in order to get it in the Java code, you'll need to call findViewById()
If your XML is declared like this, with an id:
<ImageView
android:id="#+id/my_image_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
Then you'll need to write the following before you can call setImageBitmap():
imageView = (ImageView) findViewById(R.id.my_image_view);
Additionally, you cannot make the findViewById call until after you make the call to setContentView(), because that's the call that actually creates your ImageView.
Although, looking at your code a bit further, you probably don't need to do the reflection bit, or even the setImageBitmap() call, because you can specify the drawable directly in the XML (unless you want to change it when the program is running):
<ImageView
android:id="#+id/my_image_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/announcementbc"
/>
By adding the source line, and pointing it to your drawable, the setContentView call will automatically set the correct Bitmap on the ImageView.

Answer 2

Here is the latest failed code as per the comment above
public class Tile2 extends Activity{
// Bitmap originalImage = BitmapFactory.decodeResource(getResources(), R.drawable.announcementbc);
ImageView imageView;
Bitmap originalImage;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView (R.layout.tile);
imageView = (ImageView) findViewById(R.id.ivTile);
originalImage = BitmapFactory.decodeResource(getResources(), R.drawable.announcementbc);
// ImageView imageView = new ImageView(this);
imageView.setImageBitmap(getReflection(originalImage));
//Add the image to a linear layout and display it
LinearLayout linLayout = new LinearLayout(this);
linLayout.addView(imageView, new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
// set LinearLayout as ContentView
setContentView(linLayout);
}
public static Bitmap getReflection(Bitmap image)
{
//The gap we want between the reflection and the original image
final int reflectionGap = 4;
//Get you bit map from drawable folder
Bitmap originalImage = image;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
//This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
//Create a Bitmap with the flip matix applied to it.
//We only want the bottom half of the image
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);
//Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width
, (height + height/2), Config.ARGB_8888);
//Create a new Canvas with the bitmap that's big enough for
//the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
//Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
//Draw in the gap
Paint deafaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);
//Draw in the reflection
canvas.drawBitmap(reflectionImage,0, height + reflectionGap, null);
//Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff,
TileMode.CLAMP);
//Set the paint to use this shader (linear gradient)
paint.setShader(shader);
//Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
//Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width,
bitmapWithReflection.getHeight() + reflectionGap, paint);
reflectionImage.recycle();
return bitmapWithReflection;
}
}