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Null Pointer Exception in combining two Bitmap Images

Image
By User


I am using a method to combine two Bitmap Images and write in the SDCard . The App. works fine in the emulator, but when I tried to execute in on the Real Device it throughs Null Pointer Exception at this line cs = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); that is to create a new Bitmap on which I will draw both the images that are to be combined using Canvas .



Now, here in combineImages(Bitmap background, Bitmap foreground) the first argument is the Bitmap from Camera Picture and the second is the forefround Gallery item . The Bitmap taken from Camera is a static Bitmap , I guess that is the only thing that is running me into trouble. So, could someone give me a nice solution to save a picture taken from Camera as a temporary storage so that I doesn't make any issue which using it further. 





public void combineImages(Bitmap background, Bitmap foreground) { 



        Bitmap cs = null;

        int width = 0, height = 0;

        width = background.getWidth();

        height = background.getHeight();

        cs = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

        Canvas comboImage = new Canvas(cs);

        comboImage.drawBitmap(background, 0, 0, null);

        comboImage.drawBitmap(foreground, 100, 300, null);



        String tmpImg = String.valueOf(System.currentTimeMillis()) + ".png";

        OutputStream os = null;

        try {

            os = new FileOutputStream(Environment.getExternalStorageDirectory() + File.separator + tmpImg);

            cs.compress(CompressFormat.PNG, 100, os);

        } catch (IOException e) {

            e.printStackTrace();

        }

    }


Here is my Logcat Output when I tried on Real Device.(LG Optimus Black P-970) 





10-04 12:36:08.329: ERROR/AndroidRuntime(16356): FATAL EXCEPTION: main

10-04 12:36:08.329: ERROR/AndroidRuntime(16356): java.lang.NullPointerException

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.graphics.Bitmap.createBitmap(Bitmap.java:469)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at com.cam.GalleryImageSelected.combineImages(GalleryImageSelected.java:66)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at com.cam.GalleryImageSelected$1.onClick(GalleryImageSelected.java:90)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:874)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.widget.AdapterView.performItemClick(AdapterView.java:294)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.widget.ListView.performItemClick(ListView.java:3387)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:2408)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.os.Handler.handleCallback(Handler.java:587)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.os.Handler.dispatchMessage(Handler.java:92)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.os.Looper.loop(Looper.java:123)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at android.app.ActivityThread.main(ActivityThread.java:4627)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at java.lang.reflect.Method.invokeNative(Native Method)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at java.lang.reflect.Method.invoke(Method.java:521)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)

10-04 12:36:08.329: ERROR/AndroidRuntime(16356):     at dalvik.system.NativeStart.main(Native Method)

Source: Tips4all, CCNA FINAL EXAM
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Comments

  1. UserMay 14, 2012 at 9:04 AM

    I guess the problem might be the size of the Bitmap that you are generating by taking a picture from the Camera. So, better try using Bitmap.createScaledBitmap() method.

    width = getWindowManager().getDefaultDisplay().getWidth();
    height = getWindowManager().getDefaultDisplay().getHeight();

    background = Bitmap.createScaledBitmap(background, width, height, true);


    This will scale your image according to the height-width of the device height-width. Hope this helps.

    ReplyDelete
  2. UserMay 14, 2012 at 9:04 AM

    You basically can't get a Null Pointer Exception at the line you indicated, assuming that Bitmap is correctly implemented:

    cs = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);


    createBitmap is static.
    Bitmap.Config.ARGB_8888 is static.
    width, height are ints.

    What could possibly be null? Could you post the stack trace of the exception? Are you sure about the line?

    ReplyDelete

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