java - 当我尝试访问应用程序的 Intent 数据时，为什么它会崩溃？

Question

我正在开发一个Android应用程序，当我按下按钮拍照时，它会不断崩溃，然后应该将图片保存到文件夹中并在应用程序中显示缩略图，但是一旦我拍照，应用程序就会崩溃，但仍将照片保存在所需的文件夹中。在我开始实现应用程序的照片保存部分之前，显示缩略图就可以工作了。

应用程序一旦到达此代码块就会崩溃(onActivityResult 重写函数):

        if(data.getData() == null) {
            thumbnail.add((Bitmap)data.getExtras().get("data"));
        }
        if(thumbnail.get(0) != null && thumbnail.size() > 0)
        {
            for(int i=0; i < thumbnail.size();i++){
                //Toast.makeText(getApplicationContext(), Integer.toString(thumbnail.size()), Toast.LENGTH_SHORT).show();
                createPhotoThumbnail(thumbnail);
            }
        }

这是相机调度 Intent 函数:

private void dispatchCameraIntent(){
    Intent takePicIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    if (takePicIntent.resolveActivity(getPackageManager()) != null) {
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the Files
            Toast.makeText(this, "Could not create file", Toast.LENGTH_SHORT).show();
        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            Uri photoURI = Uri.fromFile(photoFile);

            takePicIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            takePicIntent.putExtra(android.provider.MediaStore.EXTRA_SIZE_LIMIT, "720000");
            startActivityForResult(takePicIntent, REQUEST_IMAGE_CAPTURE);
            setResult(RESULT_OK, takePicIntent);
        }
    } else
    {
        //Make a toast if there is no camera app installed.
        Toast toast = Toast.makeText(this,"No program to take pictures",Toast.LENGTH_SHORT);
        toast.show();
    }
}

我添加了 logcat:

FATAL EXCEPTION: main
 Process: lt.vilniausbaldai.vilniausbaldaiofflinedefektai, PID: 14330
 Theme: themes:{}
 java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {lt.vilniausbaldai.vilniausbaldaiofflinedefektai/lt.vilniausbaldai.vilniausbaldaiofflinedefektai.MainActivity}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
     at android.app.ActivityThread.deliverResults(ActivityThread.java:3733)
     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776)
     at android.app.ActivityThread.-wrap16(ActivityThread.java)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:148)
     at android.app.ActivityThread.main(ActivityThread.java:5461)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:102)
  Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
     at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
     at java.util.ArrayList.get(ArrayList.java:308)
     at lt.vilniausbaldai.vilniausbaldaiofflinedefektai.MainActivity.onActivityResult(MainActivity.java:135)
     at android.app.Activity.dispatchActivityResult(Activity.java:6456)
     at android.app.ActivityThread.deliverResults(ActivityThread.java:3729)
     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3776) 
     at android.app.ActivityThread.-wrap16(ActivityThread.java) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:148) 
     at android.app.ActivityThread.main(ActivityThread.java:5461) 
     at java.lang.reflect.Method.invoke(Native Method)

createPhotoThumbnail方法:

private void createPhotoThumbnail(ArrayList<Bitmap> thumbnail){
    this.imageGrid = (GridView) findViewById(R.id.gridView);
    this.bitmapList = new ArrayList<>();
    ByteArrayOutputStream bytes = new ByteArrayOutputStream();

    File file = new File(Environment.getExternalStorageDirectory()+File.separator + "image.jpg");

    try {
        file.createNewFile();
        FileOutputStream fo = new FileOutputStream(file);
        fo.write(bytes.toByteArray());
        fo.close();
    }
    catch (IOException e) {
        e.printStackTrace();
    }

    try {
        for(int i = 0; i < thumbnail.size(); i++) {
            thumbnail.get(i).compress(Bitmap.CompressFormat.JPEG, 100, bytes);

            this.bitmapList.add(thumbnail.get(i));
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    this.imageGrid.setAdapter(new ImageAdapter(this, this.bitmapList));
    imageGrid.invalidate();
}

创建ImageFile方法:

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss").format(new Date());
    //String timeStamp = "picTesting";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);

    File image = File.createTempFile(
            timeStamp,  /* prefix */
            ".png",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = "file:" + image.getAbsolutePath();
    //Toast.makeText(this, mCurrentPhotoPath, Toast.LENGTH_LONG).show();
    return image;
}

Answer 1

错误很可能发生在这一行:

if(thumbnail.get(0) != null && thumbnail.size() > 0)

这是因为您首先尝试获取索引 0 处的元素，然后检查是否存在某些元素。

如果您更改这些条件的顺序，它应该可以正常工作:

if(thumbnail.size() > 0 && thumbnail.get(0) != null)

这样，您首先检查是否存在某些元素，并且只有在存在时，您才尝试获取索引 0 处的元素并检查它是否为 null。