我在void android.view.View.unFocus上获得空指针异常。我在堆栈溢出时发现了三个类似的问题但是它们都有问题，比如它们没有初始化任何变量或类似的东西。但在我的情况下，我不在这里提供任何代码。我只想知道为什么会出现这种错误。它不是每次都出现，有时候。在我的情况下，我只是从相机或画廊获取图像，然后将其与其他信息一起发布到服务器。我没有使用像onStop，onResume这样的方法。只需使用onCreate。这是完整的错误。
FATAL EXCEPTION: main
Process: com.plan9.qurbaniapps.qurbani, PID: 10768
java.lang.RuntimeException: Unable to stop activity {com.plan9.qurbaniapps.qurbani/com.plan9.qurbaniapps.qurbani.Activities.HomeActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.unFocus(android.view.View)' on a null object reference
at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:4035)
at android.app.ActivityThread.handleStopActivity(ActivityThread.java:4084)
at android.app.ActivityThread.-wrap24(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1622)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.unFocus(android.view.View)' on a null object reference
android.view.ViewGroup.removeViewInternal(ViewGroup.java:5229)
at android.view.ViewGroup.removeViewAt(ViewGroup.java:5192)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:17
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1819)
at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3227)
at android.support.v4.app.FragmentManagerImpl.dispatchStop(FragmentManager.java:3204)
at android.support.v4.app.FragmentController.dispatchStop(FragmentController.java:236)
at android.support.v4.app.FragmentActivity.onStop(FragmentActivity.java:597)
at android.support.v7.app.AppCompatActivity.onStop(AppCompatActivity.java:183)
at android.app.Instrumentation.callActivityOnStop(Instrumentation.java:1375)
at android.app.Activity.performStop(Activity.java:7181)
at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:4032)
at android.app.ActivityThread.handleStopActivity(ActivityThread.java:4084)
at android.app.ActivityThread.-wrap24(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1622)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
03-04 22:40:34.796 10768-10768/com.plan9.qurbaniapps.qurbani E/CrashlyticsCore: Failed to execute task.
java.util.concurrent.TimeoutException
at java.util.concurrent.FutureTask.get(FutureTask.java:206)
at com.crashlytics.android.core.CrashlyticsBackgroundWorker.submitAndWait(CrashlyticsBackgroundWorker.java:41)
at com.crashlytics.android.core.CrashlyticsController.handleUncaughtException(CrashlyticsController.java:312)
at com.crashlytics.android.core.CrashlyticsController$6.onUncaughtException(CrashlyticsController.java:296)
at com.crashlytics.android.core.CrashlyticsUncaughtExceptionHandler.uncaughtException(CrashlyticsUncaughtExceptionHandler.java:30)
at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1068)
at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1063)
at java.lang.Thread.dispatchUncaughtException(Thread.java:1955)
此错误会阻止crasheletics报告崩溃。所以请告诉我这个错误发生的方式。我在onResume或onPause，onStop上有什么需要做的吗？ 我现在知道空指针异常，所以它不是一个重复的问题。
这里有一些代码：
makepost.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
p = new ProgressDialog(MakePostActivity.this);
if(makepost.getText().equals("Edit")){
p.setMessage("Editing...");
}else {
p.setMessage("Posting...");
}
p.show();
if(toggleButton.isChecked()){
salevalue = "true";
}
else{
salevalue = "false";
}
// if(imageView.getTag() != null && !description.getText().toString().equals(""))
if(imageView.getTag() != null && !category.isEmpty())
{
makepost.setEnabled(false);
Toast.makeText(getApplicationContext() , "Post will be uploaded in few seconds" , Toast.LENGTH_LONG).show();
if(datafile == null) {
credentialsProvider();
TransferUtility transferUtility = new TransferUtility(s3Client, getApplicationContext());
String[] arr = imageView.getTag().toString().split("/");
File file1 = new File(imagePath);
Toast.makeText(getApplicationContext(), "category: " + category, Toast.LENGTH_LONG).show();
imageName = arr[arr.length - 1] + generateUniqueFileName();
TransferObserver observer = transferUtility.upload(
"*******", /* The bucket to upload to */
imageName, /* The key for the uploaded object */
file1 /* The file where the data to upload exists */
);
transferObserverListener(observer);
}
else{
makepost.setEnabled(false);
sendEditRequest();
}
}
else
{
p.dismiss();
Toast.makeText(getApplicationContext() , "Upload Any Image and Choose the category" , Toast.LENGTH_LONG).show();
}
}
});
private void sendrequest()
{
SharedPreferences sharedPreferences = getSharedPreferences("session" , Context.MODE_PRIVATE);
iddd = sharedPreferences.getString("id" , "");
NetworkHelper.getServices().createPost(iddd,imageName,description.getText().toString(),category,"AUDIO" , salevalue).enqueue(new Callback<String>() {
@Override
public void onResponse(Call<String> call, retrofit2.Response<String> response)
{
if(response.isSuccessful() && !response.body().toString().equals("-1"))
{
makepost.setEnabled(true);
p.dismiss();
Toast.makeText(getApplicationContext() , "Successfully Posted" , Toast.LENGTH_LONG).show();
Intent it = new Intent(MakePostActivity.this , HomeActivity.class);
if(category.equals("Goat")) {
it.putExtra("VP", 2);
}
else if(category.equals("Cow")){
it.putExtra("VP" , 1);
}
else if(category.equals("Sheep")){
it.putExtra("VP" , 3);
}
startActivity(it);
}
else
{
makepost.setEnabled(true);
p.dismiss();
Toast.makeText(getApplicationContext(),"Could'nt upload due to an error!",Toast.LENGTH_SHORT).show();
}
}
@Override
public void onFailure(Call<String> call, Throwable t)
{
makepost.setEnabled(true);
p.dismiss();
Toast.makeText(getApplicationContext(),"Could'nt upload due to an error!",Toast.LENGTH_SHORT).show();
}
});
trackScreen("Make Post Screen");
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if(EasyPermissions.hasPermissions(this, Manifest.permission.READ_EXTERNAL_STORAGE)) {
if (requestCode == 2 && resultCode == RESULT_OK && data != null && data.getData() != null) {
Uri uri = data.getData();
try {
datafile = null;
bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), uri);
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 0, bytes);
String path = MediaStore.Images.Media.insertImage(MakePostActivity.this.getContentResolver(), bitmap, uri.getPath(), null);
file = Uri.parse(path);
imagePath = getRealPathFromURI(file);
imageView = (ImageView) findViewById(R.id.iv_gallery);
Picasso.with(MakePostActivity.this).load(path).fit().into(imageView);
imageView.setTag(imagePath);
} catch (IOException e) {
e.printStackTrace();
}
}
if (requestCode == 3 && resultCode == RESULT_OK) {
datafile = null;
File file1 = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "CameraDemo");
file = FileProvider.getUriForFile(getApplicationContext(), BuildConfig.APPLICATION_ID + ".provider", file1);
bitmap = (Bitmap) data.getExtras().get("data");
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 0, bytes);
String path = MediaStore.Images.Media.insertImage(MakePostActivity.this.getContentResolver(), bitmap, file.getPath(), null);
file = Uri.parse(path);
//path.get
imageView.setTag(file.getPath());
imagePath = getRealPathFromURI(file);
Picasso.with(MakePostActivity.this).load(path).fit().into(imageView);
}
}
}
答案 0 :(得分：0)
问题出在onActivityResult。当您打开下一个活动时，此活动将被销毁。当您尝试返回此活动时imageView为空，当您尝试执行此行imageView.setTag(file.getPath());时它会崩溃
最简单的测试方法是进入手机设置 - ＆gt;开发者选项 - ＆gt;不要保持活动