Question

这是我的代码显示图片：

//从fileName中取消图像

  public Bitmap decodeSampledBitmapFromResource(String fileName,
                int reqWidth, int reqHeight) {

            // First decode with inJustDecodeBounds=true to check dimensions
            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            // BitmapFactory.decodeResource(res, resId, options);
            BitmapFactory.decodeFile(fileName, options);
            // Calculate inSampleSize
            options.inSampleSize = calculateInSampleSize(options, reqWidth,
                    reqHeight);
            options.inPreferredConfig = Bitmap.Config.ARGB_8888;
            // Decode bitmap with inSampleSize set
            options.inJustDecodeBounds = false;
            return BitmapFactory.decodeFile(fileName, options);
        }

//将图像显示到ImageView

    private void addFiletoList(String fileName) {

            DTO_FileInfo dt = new DTO_FileInfo();
            dt.FileName = fileName;

                BitmapFactory.Options options = new BitmapFactory.Options();
                options.inJustDecodeBounds = true;
                targetImage.setScaleType(ImageView.ScaleType.CENTER_CROP);
                Bitmap bmp = Bitmap.createBitmap(decodeSampledBitmapFromResource(
                        dt.FileName, 50, 50));
                targetImage.setImageBitmap(bmp);


        }

但它出现错误：

java.lang.NullPointerException
    at android.graphics.Bitmap.createBitmap(Bitmap.java:620)
    at com.noen.maihue.camerapro.CameraApp.addFiletoList(CameraApp.java:1141)
    at com.noen.maihue.camerapro.CameraApp.access$2(CameraApp.java:1123)
    at com.noen.maihue.camerapro.CameraApp$SavePhotoTask.onPostExecute(CameraApp.java:1290)
    at com.noen.maihue.camerapro.CameraApp$SavePhotoTask.onPostExecute(CameraApp.java:1)
    at android.os.AsyncTask.finish(AsyncTask.java:632)
    at android.os.AsyncTask.access$600(AsyncTask.java:177)
    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:5363)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
    at dalvik.system.NativeStart.main(Native Method)

仅在某些手机上发生：Panasonic P55 Novo，IX1AT8 Android 4.4

为什么会出现错误java.lang.NullPointerException Bitmap.java:620？

Answer 1

此代码返回null：

decodeSampledBitmapFromResource(dt.FileName, 50, 50)

导致Bitmap.decode(Bitmap)失败并抛出NullPointerException的原因。

其中一个原因可能是内存问题（没有足够的内存来读取文件和解码）或者文件（dt.FileName）无法找到或无法访问。

为什么会出现错误java.lang.NullPointerException Bitmap.java:620？

1 个答案: