0

我正在尝试将我的图像设置在我的动画中某个点的视图中。但是我得到一个空指针异常。我知道我犯了一个新手错误，但我不知道我应该做什么......当我设置我的图像 onStart() 它工作正常......但是当我在 onAnimationEnd 中设置图像时，我得到了空指针。 ..请帮忙！

public class PhotoSyncActivity extends Activity implements AnimationListener {

private Bitmap[] images;
private AnimationPhotoViewA apa1;
private AnimationPhotoViewB apa2;
private static final int move1 = 1;
private static final int move2 = 2;
private static final int move3 = 3;
private static final int move4 = 4;
private static final int move5 = 5;
private int animationmove = 0;
ArrayList<String> photoPaths;
Bitmap resizedimage2= null;




@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.photo_sync_screen);
    ArrayList<String> photoPaths = new ArrayList<String>();
    photoPaths = getAllPhotos(Environment.getExternalStorageDirectory(),
            photoPaths);
    images = new Bitmap[photoPaths.size()];
    Log.v(ACCESSIBILITY_SERVICE, "photo array!" + photoPaths);

    apa1 = (AnimationPhotoViewA) findViewById(R.id.animation_viewA);
    apa2 = (AnimationPhotoViewB) findViewById(R.id.animation_viewB);
    animationmove = PhotoAnimationProcess.moveOne(this,apa1,animationmove);

    File imgFile1 = new File(photoPaths.get(0));

    File imgFile2 = new File(photoPaths.get(1));

    if (imgFile1.exists() && imgFile2.exists())
    {
        images[0] = decodeFile(imgFile1);
        images[1] = decodeFile(imgFile2);
    }
}

@Override
protected void onStart() {
    // TODO Auto-generated method stub
    super.onStart();

    // RESIZE THE IMAGE TO A STANDARD SIZE
    Bitmap resizedimage1 = setPictureSize(images[0]);
    resizedimage2 = setPictureSize(images[1]);

    // SET IMAGE IN THE VIEW

    apa1.setImageBitmap(resizedimage1);
    apa2.setImageBitmap(resizedimage2);//HERE THE CODE WORKS WITH NO PROBLEM!!

private ArrayList<String> getAllPhotos(File dir,ArrayList<String> photoPaths)
        {
    File[] files = dir.listFiles();
    if (files != null)
    {
        for (File f : files) 
        {
            if (f != null)
            {
                if (f.isDirectory())
                {
                    getAllPhotos(f, photoPaths);
                } else
                {
                    String filePath = f.getAbsolutePath();
                    if (filePath.matches(".*\\.(jpeg|jpg)$"))
                    {
                        photoPaths.add(filePath);
                    }
                }
            }
        }
    }
    return photoPaths;
}

public void onAnimationStart(Animation animation)
{
    // TODO Auto-generated method stub

}

public void onAnimationEnd(Animation animation)
{
    // TODO Auto-generated method stub

    switch (animationmove) 
    {
    case move1:
        animationmove = PhotoAnimationProcess.moveOne(this, apa1, animationmove);
        break;
    case move2:

        //HERE I AM GETTING THE NULL POINTER WHEN SETTING IMAGEapa2.setImageBitmap(resizedimage2);
        animationmove = PhotoAnimationProcess.moveTwo(this,apa1,animationmove);

        break;
    case move3:
        animationmove = PhotoAnimationProcess.moveThree(this,apa1,animationmove);
        break;
    case move4:
        animationmove = PhotoAnimationProcess.moveFour(this,apa1,animationmove);;
        break;
    case move5:
        animationmove = PhotoAnimationProcess.moveFive(this,apa1,animationmove);
        break;

    default:
        break;
    }

    Log.v(ALARM_SERVICE, "Animation Type" + animation.toString());

}



public void onAnimationRepeat(Animation animation) {
    // TODO Auto-generated method stub

}


// Downgrade the photos
private Bitmap decodeFile(File f)
{
    Bitmap ret = null;
    try 
    {
        // Decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f), null, o);

        // The new size we want to scale to
        final int REQUIRED_SIZE = 70;

        // Find the correct scale value. It should be the power of 2.
        int scale = 1;
        while (o.outWidth / scale / 2 >= REQUIRED_SIZE
                && o.outHeight / scale / 2 >= REQUIRED_SIZE)
            scale *= 2;

        // Decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        ret = BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
    }
    catch (FileNotFoundException e)
    {
        e.printStackTrace();

    }
    return ret;

}

private Bitmap setPictureSize(Bitmap bitmapOrg)
{

    int width = bitmapOrg.getWidth();

    int height = bitmapOrg.getHeight();

    int newWidth = 250;

    int newHeight = 250;

    // calculate the scale - in this case = 0.4f

    float scaleWidth = ((float) newWidth) / width;

    float scaleHeight = ((float) newHeight) / height;

    Matrix matrix = new Matrix();

    matrix.postScale(scaleWidth, scaleHeight);
    // matrix.postRotate(x);
    // this will create image with new size
    Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0, width,
            height, matrix, true);
    return resizedBitmap;
}


}

错误：

04-08 21:27:14.764: E/AndroidRuntime(1654): FATAL EXCEPTION: main
04-08 21:27:14.764: E/AndroidRuntime(1654): java.lang.NullPointerException
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.graphics.Canvas.throwIfRecycled(Canvas.java:972)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.graphics.Canvas.drawBitmap(Canvas.java:998)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at com.uiu.registrationwizard.activities.AnimationPhotoViewB.drawPicture(AnimationPhotoViewB.java:79)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at com.uiu.registrationwizard.activities.AnimationPhotoViewB.onDraw(AnimationPhotoViewB.java:67)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.View.draw(View.java:7014)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.View.draw(View.java:7017)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.View.draw(View.java:7017)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.widget.FrameLayout.draw(FrameLayout.java:357)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.View.draw(View.java:7017)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.widget.FrameLayout.draw(FrameLayout.java:357)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2054)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewRoot.draw(ViewRoot.java:1632)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewRoot.performTraversals(ViewRoot.java:1335)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1991)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.os.Looper.loop(Looper.java:150)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at android.app.ActivityThread.main(ActivityThread.java:4385)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at java.lang.reflect.Method.invokeNative(Native Method)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at java.lang.reflect.Method.invoke(Method.java:507)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
04-08 21:27:14.764: E/AndroidRuntime(1654):     at dalvik.system.NativeStart.main(Native Method)
4

1 回答 1

0

从外观上看，resizedImage2当您在 onAnimationEnd 中设置它时为 null（注意：使用调试器验证这一点！）。重要的是要意识到Android 可能会随时终止您的活动。onCreate活动在收到 onAnimationEnd 后重新创建（即被调用），但不可见（因此 no onStart）。这意味着该resizedImage2活动的 未初始化，并且仍然为空。

resizedImage2简单的解决方案是改为初始化onCreate。

另一种解决方案是存储resizedImage2在onSaveInstanceState中，并在onCreate存在捆绑包时将其恢复。

于 2012-04-08T18:53:52.547 回答