Question

我试过以下代码，其中我试图将我上传的图像保存到SD卡文件夹中，并带有一些名称。它在上述行上给出了空指针异常。请给我任何建议。

java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法'android.graphics.Bitmap android.graphics.drawable.BitmapDrawable.getBitmap（）'

代码

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  if(requestCode==i && resultCode==RESULT_OK && data != null){
    Uri selectedImage =  data.getData();
    coverpic.setImageURI(selectedImage);
    Bitmap  image =( (BitmapDrawable)coverpic.getDrawable()).getBitmap();//This line throws the exception
    if (!direct.exists()) {
    File wallpaperDirectory = new File("/images/");
    wallpaperDirectory.mkdirs();
     }
     Bundle extras = getIntent().getExtras();
     File file = new File(new File("/images/"),extras.getString("name")+i + ".jpg" );
            if (file.exists()) {
                file.delete();
            }
     try{
    FileOutputStream out=new FileOutputStream(file);
    image.compress(Bitmap.CompressFormat.JPEG,100,out);
    out.flush();
    out.close();
    }
catch(Exception e)
            {
                e.printStackTrace();
              }
        }

Answer 1

试试这个，这会调整大小并将图像保存到手机

还要确保您在清单文件中拥有正确的权限。

这里我也使用Glide来获取位图，我认为这是一种简单的方法，它不会给出nullpointer。

在onActivityresult内部

 if(requestCode==i && resultCode==RESULT_OK && data != null){
    Uri selectedImage =  data.getData();
   select(selectedImage);

查找文件

  public void select(Uri selectedImage) {
            // TODO Auto-generated method stub
            String[] filePathColumn = {MediaStore.Images.Media.DATA};
            Cursor cursor =getActivity().getContentResolver().query(selectedImage,
                    filePathColumn, null, null, null);
            cursor.moveToFirst();
            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
            String picturePath2 = cursor.getString(columnIndex);
            cursor.close();

                save(new File(picturePath2));

        }

保存文件

public File save(final File file_) {
        // TODO Auto-generated method stub
        System.out.println("newfilepath come to resize");
        File dir = new File(Environment.getExternalStorageDirectory().getPath()
                + "/Images/");
        try {
            dir.mkdir();
        } catch (Exception e) {
            e.printStackTrace();

        }
        String filename = Environment.getExternalStorageDirectory().getPath()
                + "/Images/";
        File newfile = new File(filename);
        String Unedited_Img_Name = "myfile"
                + String.valueOf(System.currentTimeMillis()) + ".jpg";
        final File file = new File(newfile, Unedited_Img_Name);
        new AsyncTask<Void, Void, Bitmap>() {

            @Override
            protected Bitmap doInBackground(Void... params) {
                // TODO Auto-generated method stub
                Bitmap b = null;
                try {
                    b = Glide.with(getActivity()).load(file_).asBitmap().into(200,200)
                            .get();
                } catch (InterruptedException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (ExecutionException e) {
                    e.printStackTrace();
                }
                FileOutputStream fOut;
                try {
                    fOut = new FileOutputStream(file);
                    b.compress(Bitmap.CompressFormat.PNG, 100, fOut);
                    fOut.flush();
                    fOut.close();
                    b.recycle();
                } catch (Exception e) { // TODO

                }
                return null;
            }

            @Override
            protected void onPostExecute(Bitmap result) {
                // TODO Auto-generated method stub
                super.onPostExecute(result);
                String newfilepath = file.getAbsolutePath();

                int file_size = Integer
                        .parseInt(String.valueOf(file.length() / 1024));
                file_size = Integer.parseInt(String.valueOf(file_.length() / 1024));
                if (file_size < 150) {
                    newfilepath = file_.getAbsolutePath();
                }

            }
        }.execute();
        return file;
    }

在目录android中保存图像时出现空指针异常

1 个答案: