活动结果为NullPointerException，我做错了或遗漏了什么？
照片库应用程序（最终），按照android开发者网站上的说明使用内置相机拍照。 onActivityResult提供空指针。我是android新手，所以无法弄清楚。 因此，它崩溃了，我希望它在活动中显示一个位图。
public class aCamera extends AppCompatActivity {
static final int REQUEST_IMAGE_CAPTURE = 1;
static final int REQUEST_TAKE_PHOTO = 1;
ImageView imageView;
String currentPhotoPath;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_a_camera);
dispatchTakePictureIntent();
}
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) {
File photoFile = null;
try {
photoFile = createImageFile();
Log.i("DTPI-1", "dispatchTakePictureIntent: The IF AND TRY");
} catch (IOException ex) {
Log.i("DTPI-3" , "dispatchTakePictureIntent: catch");
}
// Continue only if the File was successfully created
if (photoFile != null) {
Log.i("photoURI", "dispatchTakePictureIntent: PHOTO FILE NOT EMPTY");
Uri photoURI = FileProvider.getUriForFile(this,
"com.example.android.fileprovider",
photoFile);
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
//setResult(RESULT_OK, takePictureIntent);
}
}
}
private File createImageFile() throws IOException {
// Create an image file name
Log.i("CIF -1", "createImageFile: Create FILE");
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String 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
currentPhotoPath = image.getAbsolutePath();
return image;
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
Log.i("Result", "onActivityResult: WE GET HERE");
if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
Bundle extras = data.getExtras();
Bitmap imageBitmap = (Bitmap) extras.get("data");
imageView = findViewById(R.id.imageView);
imageView.setImageBitmap(imageBitmap);
}
}
错误日志。
2019-05-06 20:01:33.555 23363-23363/com.example.camera E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.camera, PID: 23363
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {com.example.camera/com.example.camera.aCamera}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:4339)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4382)
at android.app.ActivityThread.-wrap19(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1654)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:251)
at android.app.ActivityThread.main(ActivityThread.java:6572)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference
at com.example.camera.aCamera.onActivityResult(aCamera.java:81)
at android.app.Activity.dispatchActivityResult(Activity.java:7235)
at android.app.ActivityThread.deliverResults(ActivityThread.java:4335)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4382)
at android.app.ActivityThread.-wrap19(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1654)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:251)
at android.app.ActivityThread.main(ActivityThread.java:6572)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
答案 0 :(得分：2)
相机将图像保存到photoUri中提供的Intent中。在onActivityResult中，您必须从该文件中获取Bitmap。
答案 1 :(得分：0)
第putExtra行是问题所在。删除该行并在其中接收bitmap
onActivityResult，如下所述。
@Override
protected void onActivityResult(int requestCode, int resultcode, Intent intent) {
if (requestCode == REQUEST_TAKE_PHOTO && resultcode == RESULT_OK) {
Uri uri = intent.getData();
Bitmap bitmap = null;
try {
bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri);
} catch (IOException e) {
e.printStackTrace();
}
image.setImageBitmap(bitmap);
}
}
希望这行得通。您会在类似问题的帖子上看到解释here。
答案 2 :(得分：0)
正如@aalap patel所提到的，问题不在于onActivityResult，而是在dispatchTakePictureIntent方法中只有一行。 takePictureIntent.putExtra（MediaStore.EXTRA_OUTPUT，photoURI）; 他还提到了这段代码。