我有以下简单的代码来测试 fragment 事务，因为我对 Android 比较陌生:首先，我只显示第一个 fragment ，一切都很顺利，但是当我希望在单击按钮后更改它时，我收到以下错误:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.onceuponatime, PID: 3161
java.lang.IllegalStateException: Activity has been destroyed
at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1864)
at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:649)
at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:609)
at com.example.user.onceuponatime.activity.AuthentificationActivity.onFragmentSwapRequested(AuthentificationActivity.java:63)
at com.example.user.onceuponatime.fragment.SignInFragment$2.onClick(SignInFragment.java:95)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Activity :
public class AuthentificationActivity extends AppCompatActivity implements SignInFragment.SignInFragmentCallBack
,SignUpFragment.SignUpFragmentCallBack{
public static final String SIGNINFRAGMENT_TAG = "signinfragment";
public static final String SIGNUPFRAGMENT_TAG = "signupfragment";
public static final int SIGNIN_FRAGMENT_ID = 846464;
public static final int SIGNUP_FRAGMENT_ID = 125478;
public static final int LOST_PWD_FRAGMENT_ID = 85546;
private FragmentManager mFragmentManager;
private SignInFragment mSignInFragment;
private SignUpFragment mSignUpFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_authentification);
mSignInFragment = SignInFragment.getInstance();
mFragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();
fragmentTransaction.add(mSignInFragment,SIGNINFRAGMENT_TAG);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
@Override
public void onFragmentSwapRequested(int FragmentId) {
mFragmentManager = this.getSupportFragmentManager();
FragmentTransaction fgTransaction = mFragmentManager.beginTransaction();
switch(FragmentId) {
case SIGNUP_FRAGMENT_ID:
if(!isFinishing()) {
mSignUpFragment = (SignUpFragment) mFragmentManager.findFragmentByTag(SIGNUPFRAGMENT_TAG);
if (mSignUpFragment == null) {
mSignUpFragment = SignUpFragment.getInstance();
fgTransaction.replace(R.id.fragment_container, mSignUpFragment, SIGNUPFRAGMENT_TAG);
} else {
fgTransaction.show(mSignUpFragment);
}
fgTransaction.addToBackStack(null);
fgTransaction.commit();
}
break;
case LOST_PWD_FRAGMENT_ID:
break;
}
}
}
注册 fragment :
public class SignUpFragment extends Fragment {
FragmentSignUpBinding signUpBinding;
private EditText mEmailEdit,mPasswordEdit;
private Button btnRegister,btnLogin;
private ProgressBar mProgressBar;
private CoordinatorLayout mCoordinatorLayout;
private FirebaseAuth mAuth;
private SignUpFragmentCallBack mCallBack;
public interface SignUpFragmentCallBack {
void onFragmentSwapRequested(int fragmentId);
}
public SignUpFragment() {
}
public static SignUpFragment getInstance() {
SignUpFragment fragment = new SignUpFragment();
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
signUpBinding = DataBindingUtil.setContentView(getActivity(),R.layout.fragment_sign_up);
mEmailEdit = signUpBinding.emailSignup;
mPasswordEdit = signUpBinding.passwordSignup;
btnLogin = signUpBinding.loginRedirectButton;
btnRegister = signUpBinding.registerButton;
mProgressBar = signUpBinding.progressBarSignup;
mCoordinatorLayout = signUpBinding.coordinatorSignup;
mCallBack = new AuthentificationActivity();
mAuth = FirebaseAuth.getInstance();
btnLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mCallBack instanceof SignUpFragmentCallBack)
mCallBack.onFragmentSwapRequested(AuthentificationActivity.SIGNIN_FRAGMENT_ID);
}
});
btnRegister.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onRegisterClicked();
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_sign_up, container, false);
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
}
private void onRegisterClicked() {
String email = mEmailEdit.getText().toString().trim();
final String pwd = mPasswordEdit.getText().toString().trim();
if(TextUtils.isEmpty(email)) {
Snackbar.make(mCoordinatorLayout,getString(R.string.no_email_entered),Snackbar.LENGTH_LONG).show();
return;
}
if(TextUtils.isEmpty(pwd)) {
Snackbar.make(mCoordinatorLayout,getString(R.string.no_password_entered),Snackbar.LENGTH_LONG).show();
return;
}
mProgressBar.setVisibility(View.VISIBLE);
mAuth.createUserWithEmailAndPassword(email,pwd).addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if(task.isSuccessful()) {
startActivity(new Intent(getActivity(), MainActivity.class));
getActivity().finish();
}
else {
mProgressBar.setVisibility(View.GONE);
Snackbar.make(mCoordinatorLayout,task.getException().toString(),Snackbar.LENGTH_LONG).show();
}
}
});
}
@Override
public void onDetach() {
super.onDetach();
}
}
我读过很多关于类似问题的帖子，有些说用 if(!isFinished()) 包装事务，有些说重写 onDestroy，但没有一个起作用，我相信解决方案更简单。
编辑: 这是我的 SignInFragment 和身份验证 Activity xml:
登录 fragment :
public class SignInFragment extends Fragment {
FragmentSignInBinding signInBinding;
private CoordinatorLayout mCoordinatorLayout;
private EditText mEmailEdit,mPasswordEdit;
private Button btnSignIn,btnSignUp,btnLostPwd;
private ProgressBar mProgressBar;
private FirebaseAuth mAuth;
private SignInFragmentCallBack mCallBack;
public interface SignInFragmentCallBack {
void onFragmentSwapRequested(int FragmentId);
}
public SignInFragment() {}
public static SignInFragment getInstance() {
return new SignInFragment();
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mCallBack = (SignInFragmentCallBack) context;
} catch(ClassCastException e) {
throw new ClassCastException(context.toString() + " must implements SignInCallaback");
}
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
signInBinding = DataBindingUtil.setContentView(getActivity(),R.layout.fragment_sign_in);
mEmailEdit = signInBinding.emailSignin;
mPasswordEdit = signInBinding.passwordSignin;
mProgressBar = signInBinding.progressBarSignIn;
btnSignIn = signInBinding.signInButton;
btnSignUp = signInBinding.signUpButton;
btnLostPwd = signInBinding.passwordReset;
mCoordinatorLayout = signInBinding.coordinatorSignin;
mAuth = FirebaseAuth.getInstance();
btnSignIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
signInAction();
}
});
btnSignUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mCallBack instanceof SignInFragmentCallBack)
mCallBack.onFragmentSwapRequested(AuthentificationActivity.SIGNUP_FRAGMENT_ID);
}
});
btnLostPwd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mCallBack instanceof SignInFragmentCallBack)
mCallBack.onFragmentSwapRequested(AuthentificationActivity.LOST_PWD_FRAGMENT_ID);
}
});
}
private void signInAction() {
String email = mEmailEdit.getText().toString().trim();
final String password = mPasswordEdit.getText().toString().trim();
if(TextUtils.isEmpty(email)) {
Snackbar.make(mCoordinatorLayout,getString(R.string.no_email_entered),Snackbar.LENGTH_LONG).show();
return;
}
if(TextUtils.isEmpty(password)) {
Snackbar.make(mCoordinatorLayout,getString(R.string.no_password_entered),Snackbar.LENGTH_LONG).show();
return;
}
mProgressBar.setVisibility(View.VISIBLE);
mAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
mProgressBar.setVisibility(View.GONE);
if(task.isSuccessful()) {
Snackbar.make(mCoordinatorLayout,getString(R.string.login_success),Snackbar.LENGTH_LONG).show();
startActivity(new Intent(getActivity(), MainActivity.class));
getActivity().finish();
}
else
{
Snackbar.make(mCoordinatorLayout,getString(R.string.login_failed),Snackbar.LENGTH_LONG).show();
}
}
});
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_sign_in,container,false);
}
@Override
public void onResume() {
super.onResume();
mProgressBar.setVisibility(View.GONE);
}
}
身份验证 xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_authentification"
android:layout_width="match_parent"
android:layout_height="match_parent" tools:context="com.example.user.onceuponatime.activity.AuthentificationActivity">
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/fragment_container">
</FrameLayout>
</LinearLayout>
EDIT2:新的堆栈跟踪:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.user.onceuponatime, PID: 8674
java.lang.IllegalArgumentException: No view found for id 0x7f0d007f (com.example.user.onceuponatime:id/fragment_container) for fragment SignUpFragment{2b0b994 #1 id=0x7f0d007f signupfragment}
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1293)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:757)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2355)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2146)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2098)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2008)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
SignInFragment xml:
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" >
<android.support.design.widget.CoordinatorLayout
android:id="@+id/coordinator_signin"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.user.onceuponatime.fragment.SignInFragment">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:orientation="vertical"
android:background="@color/colorPrimaryDark"
android:padding="@dimen/activity_horizontal_margin"
>
<ImageView
android:layout_width="@dimen/logo_wh"
android:layout_height="@dimen/logo_wh"
android:src="@mipmap/ic_launcher"
android:layout_gravity="center_horizontal"
android:layout_marginBottom="30dp"/>
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="@+id/email_signin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/email_input"
android:textColor="@android:color/white"
android:maxLines="1"
android:inputType="textEmailAddress"
/>
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:maxLines="1"
android:id="@+id/password_signin"
android:inputType="textPassword"
android:imeActionId="@+id/login"
android:imeOptions="actionUnspecified"
android:textColor="@android:color/white"
android:focusableInTouchMode="true"
android:hint="@string/password_input"
/>
</android.support.design.widget.TextInputLayout>
<Button
android:id="@+id/sign_in_button"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:background="@color/colorAccent"
android:text="@string/short_signin"
android:textColor="@android:color/black"
android:textStyle="bold"
android:textAlignment="center"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/sign_up_button"
android:background="@null"
android:layout_marginTop="20dp"
android:textAllCaps="false"
android:textColor="@color/colorAccent"
android:text="@string/link_register"
/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/password_reset"
android:background="@null"
android:layout_marginTop="20dp"
android:textAllCaps="false"
android:text="@string/lost_password"
android:textColor="@android:color/white"
android:textSize="15dp"
/>
</LinearLayout>
<ProgressBar
android:id="@+id/progressBarSignIn"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_gravity="center|bottom"
android:layout_marginBottom="20dp"
android:visibility="gone" />
</android.support.design.widget.CoordinatorLayout>
</layout>
最佳答案
这就是问题所在:
mCallBack = new AuthentificationActivity();
您无法使用 new 实例化 Activity 并使其正常工作。此外，该新实例无论如何都不会是当前的托管实例。
相反，您希望将当前托管 Activity 实例强制转换为您的界面。由于您使用的是 Fragment 支持，因此您可以使用 getActivity() 或 getContext() 来检索该实例，因为两者都会返回与 Activity 主机相同的对象。例如:
mCallBack = (SignUpFragmentCallBack) getContext();
这至少足以测试您当前的设置。然而，更简洁的实现可能是在 onAttach() 中使用 ClassCastException 的 try-catch 执行此转换，我们可以在其中抛出一个如果失败，则提供更多信息异常。
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mCallBack = (SignUpFragmentCallBack) context;
}
catch (ClassCastException e) {
throw new ClassCastException(context.toString() +
" must implement the SignUpFragmentCallBack interface");
}
}
关于java - fragment 提交时出现 IllegalStatementException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42428423/