成功登录后，家庭活动无法在设备中启动，并且应用程序将崩溃。我能够很好地开展其他活动。因此，我相信这里的问题在于我的Home活动（以及所有其他包含BottomNavigation的活动）。
有人可以指出我的错误吗？谢谢！
Home.java
public class Home extends AppCompatActivity implements AdapterView.OnItemSelectedListener{
private TextView mTextMessage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
mTextMessage = (TextView) findViewById(R.id.message);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
final FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Creating the instance of PopupMenu
final PopupMenu popup = new PopupMenu(Home.this, fab);
//Inflating the Popup using xml file
popup.getMenuInflater()
.inflate(R.menu.popup_menu, popup.getMenu());
//registering popup with OnMenuItemClickListener
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(
Home.this,
"You Clicked : " + item.getTitle(),
Toast.LENGTH_SHORT
).show();
return true;
}
});
popup.show(); //showing popup menu
}
});
final ImageButton ib = (ImageButton) findViewById(R.id.ib);
ib.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Creating the instance of PopupMenu
final PopupMenu popup = new PopupMenu(Home.this, ib);
//Inflating the Popup using xml file
popup.getMenuInflater()
.inflate(R.menu.popup_switchgrp, popup.getMenu());
//registering popup with OnMenuItemClickListener
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(
Home.this,
"You Clicked : " + item.getTitle(),
Toast.LENGTH_SHORT
).show();
return true;
}
});
popup.show(); //showing popup menu
}
});
Spinner spinner = findViewById(R.id.spinner1);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.DeviceLocation, android.R.layout.simple_spinner_dropdown_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(this);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
mTextMessage.setText(R.string.title_home);
return true;
case R.id.navigation_scenes:
mTextMessage.setText(R.string.title_scenes);
openScenesPage();
return true;
case R.id.navigation_security:
mTextMessage.setText(R.string.title_security);
openSecurityPage();
return true;
case R.id.navigation_myinfo:
mTextMessage.setText(R.string.title_myinfo);
openMyInfoPage();
return true;
}
return true;
}
};
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String text = parent.getItemAtPosition(position).toString();
Toast.makeText(parent.getContext(), text, Toast.LENGTH_SHORT).show();
}
public void onNothingSelected(AdapterView<?> parent) {
}
private void openScenesPage(){
Intent intent = new Intent(this, Home.class);
startActivity(intent);
}
private void openSecurityPage(){
Intent intent = new Intent(this, Home.class);
startActivity(intent);
}
private void openMyInfoPage(){
Intent intent = new Intent(this, Home.class);
startActivity(intent);
}
}
LOGCAT：
2018-11-19 16:46:30.953 1778-1778/? E/adTracker: Value 60172784179-1477976237@g.us of type java.lang.String cannot be converted to JSONObject
--------- beginning of system
2018-11-19 16:46:36.789 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:46:45.009 751-751/? E/cnss-daemon: gateway mac address: %02x:%02x:%02x:%02x:%02x:%02x
: 00:00:00:00:00:00
2018-11-19 16:46:45.010 751-751/? E/cnss-daemon: Invalid mac address: 0x555555f110M
2018-11-19 16:46:49.000 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:46:50.046 16022-16022/? E/ResourcesFlusher: Could not retrieve ResourcesImpl#mDrawableCache field
java.lang.NoSuchFieldException: No field mDrawableCache in class Landroid/content/res/MiuiResourcesImpl; (declaration of 'android.content.res.MiuiResourcesImpl' appears in /system/framework/framework.jar)
at java.lang.Class.getDeclaredField(Native Method)
at android.support.v7.app.ResourcesFlusher.flushNougats(Twttr:141)
at android.support.v7.app.ResourcesFlusher.flush(Twttr:46)
at android.support.v7.app.AppCompatDelegateImplV14.updateForNightMode(Twttr:221)
at android.support.v7.app.AppCompatDelegateImplV14.applyDayNight(Twttr:93)
at android.support.v7.app.AppCompatActivity.onCreate(Twttr:73)
at com.twitter.app.common.base.BaseFragmentActivity.onCreate(Twttr:66)
at com.twitter.app.common.inject.InjectedFragmentActivity.onCreate(Twttr:46)
at com.twitter.app.common.abs.AbsFragmentActivity.onCreate(Twttr:129)
at com.twitter.app.common.base.TwitterFragmentActivity.onCreate(Twttr:158)
at android.app.Activity.performCreate(Activity.java:6875)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2694)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2802)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1549)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:163)
at android.app.ActivityThread.main(ActivityThread.java:6379)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
2018-11-19 16:46:55.228 16022-16022/? E/libEGL: call to OpenGL ES API with no current context (logged once per thread)
2018-11-19 16:46:55.715 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:46:55.862 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:46:55.870 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:46:55.870 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.configureVideoTunnelMode not implemented
2018-11-19 16:46:55.870 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.useAndroidNativeBuffer is supported
2018-11-19 16:46:55.872 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:46:55.873 738-2028/? E/OMXNodeInstance: getConfig(2e200ba:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:46:55.930 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:46:55.930 738-2028/? E/OMXNodeInstance: getConfig(2e200ba:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:46:55.964 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:46:55.964 738-2028/? E/OMXNodeInstance: getConfig(2e200ba:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:00.810 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:47:00.817 2685-2897/? E/WtProcessController: Error pid or pid not exist
2018-11-19 16:47:00.824 2685-2897/? E/WtProcessController: Error pid or pid not exist
2018-11-19 16:47:00.856 15173-15173/? E/SearchServiceClient: SearchServiceClient disposed and cannot be reused.
2018-11-19 16:47:00.861 15173-15173/? E/SearchServiceClient: SearchServiceClient disposed and cannot be reused.
2018-11-19 16:47:00.862 15173-15173/? E/SearchServiceClient: SearchServiceClient disposed and cannot be reused.
2018-11-19 16:47:01.566 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:47:01.572 733-16282/? E/ACDB-LOADER: Error: ACDB AudProc vol returned = -19
2018-11-19 16:47:01.573 733-16282/? E/ACDB-LOADER: Error: ACDB AFE returned = -19
2018-11-19 16:47:01.685 2035-12645/? E/ctxmgr: [ProducerStatusImpl]updateStateForNewContextData: inactive, contextName=7
2018-11-19 16:47:01.888 2035-2035/? E/BeaconBle: Scan couldn't start for Places
2018-11-19 16:47:11.151 15173-16305/? E/DoodleDataUtils: Doodle: bad search_url:
2018-11-19 16:47:11.166 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:47:11.172 733-16322/? E/ACDB-LOADER: Error: ACDB AudProc vol returned = -19
2018-11-19 16:47:11.173 733-16322/? E/ACDB-LOADER: Error: ACDB AFE returned = -19
2018-11-19 16:47:12.121 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:47:12.360 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:47:12.366 738-738/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:47:12.366 738-738/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.configureVideoTunnelMode not implemented
2018-11-19 16:47:12.366 738-738/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.useAndroidNativeBuffer is supported
2018-11-19 16:47:12.368 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:47:12.368 738-2028/? E/OMXNodeInstance: getConfig(2e200bb:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:12.405 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:47:12.406 738-2028/? E/OMXNodeInstance: getConfig(2e200bb:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:12.410 15173-16368/? E/ACodec: Unexpected command completion in ExecutingToIdleState: PortDisable(2) Loaded(1)
2018-11-19 16:47:12.411 15173-16368/? E/ACodec: signalError(omxError 0x80001001, internalError -2147483646)
2018-11-19 16:47:12.411 15173-16367/? E/MediaCodec: Codec reported err 0x80000002, actionCode 0, while in state 10
2018-11-19 16:47:17.581 2035-16289/? E/NetworkScheduler: Invalid component specified.
2018-11-19 16:47:17.602 2035-15450/? E/NetworkScheduler: Invalid component specified.
2018-11-19 16:47:17.631 2035-15450/? E/NetworkScheduler: Invalid component specified.
2018-11-19 16:47:23.592 16342-16342/com.abc.def E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.abc.def, PID: 16342
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setVisibility(int)' on a null object reference
at com.abc.def.LoginActivity.showProgress(LoginActivity.java:245)
at com.abc.def.LoginActivity.attemptLogin(LoginActivity.java:206)
at com.abc.def.LoginActivity.access$000(LoginActivity.java:41)
at com.abc.def.LoginActivity$2.onClick(LoginActivity.java:92)
at android.view.View.performClick(View.java:5647)
at android.view.View$PerformClick.run(View.java:22462)
at android.os.Handler.handleCallback(Handler.java:754)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:163)
at android.app.ActivityThread.main(ActivityThread.java:6379)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
2018-11-19 16:47:23.713 1527-1669/? E/InputDispatcher: channel '272b664 com.abc.def/com.abc.def.LoginActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
2018-11-19 16:47:23.714 477-2464/? E/ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only
2018-11-19 16:47:23.742 2414-2450/? E/octvm_klo: read: Unexpected EOF!
2018-11-19 16:47:23.921 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:47:23.928 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.storeANWBufferInMetadata not implemented
2018-11-19 16:47:23.928 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.configureVideoTunnelMode not implemented
2018-11-19 16:47:23.928 738-2028/? E/OMX-VDEC-1080P: Extension: OMX.google.android.index.useAndroidNativeBuffer is supported
2018-11-19 16:47:23.930 738-946/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:47:23.930 738-946/? E/OMXNodeInstance: getConfig(2e200bc:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:23.965 15173-15173/? E/SrpContentController: Attach/Detach events sent when controller is already destroyed
2018-11-19 16:47:23.966 15173-15173/? E/SrpContentController: Show/Hide events sent when controller is already destroyed
2018-11-19 16:47:23.982 2035-16290/? E/ctxmgr: [ProducerStatusImpl]updateStateForNewContextData: inactive, contextName=7
2018-11-19 16:47:24.014 15173-15173/? E/SrpContentController: Show/Hide events sent when controller is already destroyed
2018-11-19 16:47:24.026 15173-15173/? E/SrpContentController: Show/Hide events sent when controller is already destroyed
2018-11-19 16:47:24.048 738-946/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:47:24.048 738-946/? E/OMXNodeInstance: getConfig(2e200bc:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:24.154 738-2028/? E/OMX-VDEC-1080P: Does not handle dataspace request
2018-11-19 16:47:24.154 738-2028/? E/OMXNodeInstance: getConfig(2e200bc:qcom.decoder.avc, ??(0x7f000062)) ERROR: UnsupportedSetting(0x80001019)
2018-11-19 16:47:24.180 733-16422/? E/ACDB-LOADER: Error: ACDB AudProc vol returned = -19
2018-11-19 16:47:24.181 733-16422/? E/ACDB-LOADER: Error: ACDB AFE returned = -19
2018-11-19 16:47:24.364 2035-2035/? E/BeaconBle: Scan couldn't start for Places
Login.java
public class LoginActivity extends AppCompatActivity implements LoaderCallbacks<Cursor> {
private static final int REQUEST_READ_CONTACTS = 0;
private static final String[] DUMMY_CREDENTIALS = new String[]{
"foo@example.com:hello", "bar@example.com:world"
};
private UserLoginTask mAuthTask = null;
// UI references.
private AutoCompleteTextView mEmailView;
private EditText mPasswordView;
private View mProgressView;
private View mLoginFormView;
private Button mSignInButton;
private Button mForgotPasswordButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// Set up the login form.
mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
populateAutoComplete();
mPasswordView = (EditText) findViewById(R.id.password);
mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
if (id == EditorInfo.IME_ACTION_DONE || id == EditorInfo.IME_NULL) {
attemptLogin();
return true;
}
return false;
}
});
Button mSignInButton = (Button) findViewById(R.id.sign_in_button);
mSignInButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
attemptLogin();
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
}
});
final Button mForgotPasswordButton = (Button) findViewById(R.id.forgot_password_button);
mForgotPasswordButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
openForgotPassword();
}
});
}
private void populateAutoComplete() {
if (!mayRequestContacts()) {
return;
}
getLoaderManager().initLoader(0, null, this);
}
private boolean mayRequestContacts() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
return true;
}
if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
return true;
}
if (shouldShowRequestPermissionRationale(READ_CONTACTS)) {
Snackbar.make(mEmailView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE)
.setAction(android.R.string.ok, new View.OnClickListener() {
@Override
@TargetApi(Build.VERSION_CODES.M)
public void onClick(View v) {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
});
} else {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
return false;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
if (requestCode == REQUEST_READ_CONTACTS) {
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
populateAutoComplete();
}
}
}
private void attemptLogin() {
if (mAuthTask != null) {
return;
}
// Reset errors.
mEmailView.setError(null);
mPasswordView.setError(null);
// Store values at the time of the login attempt.
String email = mEmailView.getText().toString();
String password = mPasswordView.getText().toString();
boolean cancel = false;
View focusView = null;
// Check for a valid password, if the user entered one.
if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) {
mPasswordView.setError(getString(R.string.error_invalid_password));
focusView = mPasswordView;
cancel = true;
}
else if (TextUtils.isEmpty(password)) {
mPasswordView.setError("Password is empty");
focusView = mPasswordView;
cancel = true;
}
// Check for a valid email address.
if (TextUtils.isEmpty(email)) {
mEmailView.setError(getString(R.string.error_field_required));
focusView = mEmailView;
cancel = true;
} else if (!isEmailValid(email)) {
mEmailView.setError(getString(R.string.error_invalid_email));
focusView = mEmailView;
cancel = true;
}
if (cancel) {
// There was an error; don't attempt login and focus the first
// form field with an error.
focusView.requestFocus();
} else {
// Show a progress spinner, and kick off a background task to
// perform the user login attempt.
showProgress(true);
mAuthTask = new UserLoginTask(email, password);
mAuthTask.execute((Void) null);
}
}
private boolean isEmailValid(String email) {
//TODO: Replace this with your own logic
return email.contains("@") && email.contains(".");
}
private boolean isPasswordValid(String password) {
//TODO: Replace this with your own logic
return password.length() > 4;
}
private void openForgotPassword(){
Intent intent = new Intent(this, ForgotPasswordActivity.class);
startActivity(intent);
}
public void startHome(){
Intent intent = new Intent(this, Home.class);
startActivity(intent);
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
private void showProgress(final boolean show) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
int shortAnimTime = getResources().getInteger(android.R.integer.config_shortAnimTime);
mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
mLoginFormView.animate().setDuration(shortAnimTime).alpha(
show ? 0 : 1).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
}
});
mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
mProgressView.animate().setDuration(shortAnimTime).alpha(
show ? 1 : 0).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
}
});
} else {
mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
}
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
return new CursorLoader(this,
// Retrieve data rows for the device user's 'profile' contact.
Uri.withAppendedPath(ContactsContract.Profile.CONTENT_URI,
ContactsContract.Contacts.Data.CONTENT_DIRECTORY), ProfileQuery.PROJECTION,
// Select only email addresses.
ContactsContract.Contacts.Data.MIMETYPE +
" = ?", new String[]{ContactsContract.CommonDataKinds.Email
.CONTENT_ITEM_TYPE},
ContactsContract.Contacts.Data.IS_PRIMARY + " DESC");
}
@Override
public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
List<String> emails = new ArrayList<>();
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
emails.add(cursor.getString(ProfileQuery.ADDRESS));
cursor.moveToNext();
}
addEmailsToAutoComplete(emails);
}
@Override
public void onLoaderReset(Loader<Cursor> cursorLoader) {
}
private void addEmailsToAutoComplete(List<String> emailAddressCollection) {
//Create adapter to tell the AutoCompleteTextView what to show in its dropdown list.
ArrayAdapter<String> adapter =
new ArrayAdapter<>(LoginActivity.this,
android.R.layout.simple_dropdown_item_1line, emailAddressCollection);
mEmailView.setAdapter(adapter);
}
private interface ProfileQuery {
String[] PROJECTION = {
ContactsContract.CommonDataKinds.Email.ADDRESS,
ContactsContract.CommonDataKinds.Email.IS_PRIMARY,
};
int ADDRESS = 0;
int IS_PRIMARY = 1;
}
/**
* Represents an asynchronous login/registration task used to authenticate
* the user.
*/
public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {
private final String mEmail;
private final String mPassword;
UserLoginTask(String email, String password) {
mEmail = email;
mPassword = password;
}
@Override
protected Boolean doInBackground(Void... params) {
// TODO: attempt authentication against a network service.
try {
// Simulate network access.
Thread.sleep(2000);
} catch (InterruptedException e) {
return false;
}
for (String credential : DUMMY_CREDENTIALS) {
String[] pieces = credential.split(":");
if (pieces[0].equals(mEmail)) {
// Account exists, return true if the password matches.
return pieces[1].equals(mPassword);
}
}
// TODO: register the new account here.
return true;
}
@Override
protected void onPostExecute(final Boolean success) {
mAuthTask = null;
showProgress(false);
if (success) {
startHome();
} else {
mPasswordView.setError(getString(R.string.error_incorrect_password));
mPasswordView.requestFocus();
}
}
@Override
protected void onCancelled() {
mAuthTask = null;
showProgress(false);
}
}
}
答案 0 :(得分：0)
实际上，您可以在mProgressView单击中初始化mLoginFormView和mSignInButton。这是一种不好的做法，会使NPE失效，所以我建议像下面这样添加两个视图onCreate（）的移动初始化并从onClickListener中删除。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
//other codes
}
希望有帮助
答案 1 :(得分：0)
在使用mProgressView和mLoginFormView之前，先给它们赋值。
@Override
public void onClick(View view) {
attemptLogin();
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
}
从崩溃日志中可以明显看出，尝试登录将使用仅在之后设置的mProgressView。所以可能会起作用：
@Override
public void onClick(View view) {
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
attemptLogin();
}
Radesh的答案也可能有用。