在真实设备上从 OnCreate 之外的方法获取空值答案

【问题标题】：Getting null value from method outside OnCreate on real device在真实设备上从 OnCreate 之外的方法获取空值
【发布时间】：2017-04-20 01:15:09
【问题描述】：

我有一个非常简单的应用程序，可以直接从相机将图片上传到 Firebase，它是按照 Android 开发者页面的原始文档编写的。它在模拟器上运行良好，但在我的 Galaxy S4 上它崩溃了。变量 imageFileName 在 onActivityResult 上为空，但仅在 GS4 中。以下是模拟器中的内容：

I/TAG 0:: 文件名 JPEG_20170420_005617_

I/TAG 1:: 文件名 JPEG_20170420_005617_

这是 GS4 中的内容：

I/TAG 0:: 文件名 JPEG_20170420_005617_

I/TAG 1:: FILENAME null

为什么它会无中生有？为什么在 S4 上？没有这个值，我无法将文件放入 Firebase。仅适用于 GS4。

感谢您的帮助。

private FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
private StorageReference mStorage;
private Button mSelect, mCam;
public Uri uri, photoURI;
private String imageFileName;

private ProgressDialog mProgressDialog;

private static final int GALLERY_INTENT = 2;
private static final int CAMERA_REQUEST_CODE = 1;
static final int REQUEST_TAKE_PHOTO = 1;

String mCurrentPhotoPath;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mStorage = FirebaseStorage.getInstance().getReference();

    mSelect = (Button) findViewById(R.id.first_but);
    mCam = (Button) findViewById(R.id.sec_but);

    mProgressDialog = new ProgressDialog(this);

    mCam.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            //startActivityForResult(intent, CAMERA_REQUEST_CODE);
            dispatchTakePictureIntent();


        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if(requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK) {
        Log.i("TAG 1: ", "FILENAME " + imageFileName);
    }
}

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = image.getAbsolutePath();
    return image;
}

private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File
        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            photoURI = FileProvider.getUriForFile(this,
                    "com.example.android.fileprovider",
                    photoFile);
            Log.i("TAG 0: ", "FILENAME " + imageFileName);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}

【问题讨论】：

没人知道吗？它只发生在我的三星 S4..

标签： variables null oncreate

【解决方案1】：

奇怪的是，解决问题的方法是将其添加到 AdroidManifest.xml

<activity
    android:name=".YourActivity"
    android:configChanges="orientation|keyboardHidden|screenSize"
    android:screenOrientation="portrait" >
</activity>

感谢@Janine Kroser

原帖：Photo capture Intent causes NullPointerException on Samsung phones only

除了“三星很奇怪”之外，我仍然想要一些解释。方向改变是否会破坏某些包含数据的活动？

【讨论】：