java - EditText 不更新其文本

Question

编辑2:使用

fragTransaction.add(fragment, tag);

而不是

fragTransaction.add(id, fragment);

或者

出于某种奇怪的原因，删除 MainActivity 中的所有 Fragments 代码会使应用程序再次运行。

<小时/>

按下按钮时，通过 .getText().toString() 获取文本将返回 null/空。

尝试手动 .setText("something")，它在调用 .getText().toString() 时起作用，但是，

当文本被修改时，调用.getText().toString()仍然会返回“something”。

MainActivity.java

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_main);

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragTransaction = fragmentManager.beginTransaction();

        Fragment loginFrag = new LoginFragment();

        fragTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
        fragTransaction.add(R.id.mainFrag, loginFrag);
        fragTransaction.commit();
    }

LoginFragment.java

public class LoginFragment extends Fragment{
    EditText fieldID;
    EditText fieldPassword;
    Button logButton;
    private FirebaseAuth mAuth;
    View view;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.login_menu, container, false);
    }

    @Override
    public void onViewCreated(View v, Bundle savedInstanceState) {
        super.onViewCreated(v, savedInstanceState);
        mAuth = FirebaseAuth.getInstance();
        view = v;

        fieldID = v.findViewById(R.id.fieldID);
        fieldPassword = v.findViewById(R.id.fieldPassword);
        logButton = v.findViewById(R.id.button_login);



        logButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                signIn(fieldID.getText().toString(), fieldPassword.getText().toString());
            }
        });
    }

    private void signIn(String email, String password) {
        System.out.println("Email: " + email);
        System.out.println("Pass: " + password);

        if(!email.isEmpty() && !password.isEmpty()) {
            mAuth.signInWithEmailAndPassword(email, password)
                    .addOnCompleteListener(getActivity(), new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            if (task.isSuccessful()) {
                                // Sign in success, update UI with the signed-in user's information
                                Log.d("Auth", "signInWithEmail:success");
                                FirebaseUser user = mAuth.getCurrentUser();
                                //updateUI(user);

                                view.findViewById(R.id.logoMain).setVisibility(View.GONE);
                            } else {
                                // If sign in fails, display a message to the user.
                                Log.w("Auth", "signInWithEmail:failure", task.getException());
                                //updateUI(null);
                            }
                        }
                    });
        }
    }
}

主要 Activity

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".presenter.Activity.MainActivity">

    <fragment
        android:id="@+id/mainFrag"
        android:name="com.raze.mfa.presenter.Fragment.LoginFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

fragment 布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFFFF"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="110dp"
        android:adjustViewBounds="true"
        android:scaleType="fitXY"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/logoMain"
        app:layout_constraintVertical_bias="1.0"
        app:srcCompat="@drawable/bak"
        tools:srcCompat="@drawable/bak" />

    <ImageView
        android:id="@+id/iconlock"
        android:layout_width="43dp"
        android:layout_height="43dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="28dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toStartOf="@+id/fieldPassword"
        app:layout_constraintHorizontal_bias="0.523"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/iconuser"
        app:srcCompat="@mipmap/lockicon" />

    <ImageView
        android:id="@+id/iconuser"
        android:layout_width="43dp"
        android:layout_height="43dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="320dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toStartOf="@+id/fieldID"
        app:layout_constraintHorizontal_bias="0.522"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@mipmap/usericon" />

    <Button
        android:id="@+id/button_login"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="@string/loginText"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/fieldPassword"
        app:layout_constraintVertical_bias="0.188" />

    <EditText
        android:id="@+id/fieldPassword"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="72dp"
        android:autofillHints=""
        android:ems="10"
        android:hint="@string/password"
        android:inputType="textPassword"
        android:singleLine="true"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/fieldID" />

    <EditText
        android:id="@+id/fieldID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="320dp"
        android:layout_marginEnd="72dp"
        android:autofillHints=""
        android:ems="10"
        android:hint="@string/email"
        android:inputType="textEmailAddress"
        android:singleLine="true"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/logoMain"
        android:layout_width="128dp"
        android:layout_height="128dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="108dp"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        app:layout_constraintBottom_toTopOf="@+id/fieldID"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0"
        app:srcCompat="@drawable/logoimg" />

    <Button
        android:id="@+id/button_register"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="@string/register"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button_login"
        app:layout_constraintVertical_bias="0.0" />

</androidx.constraintlayout.widget.ConstraintLayout>

不相关:我已经在 Google 上搜索了几乎所有内容，但似乎我还不了解使用 Fragments、Activites、context、Views 等的基础知识。

Answer 1

好的，我明白了，您正在使用 <fragment/>标签已经在您的 MainActivity 布局中，然后添加 FragmentTransaction一个 fragment 。

交易地址为FrameLayout空的容器并带有 fragment 。当您通过 <fragment/> 静态添加 fragment 时标记 fragment 已加载到屏幕中。

当您向 fragment 标记添加新 fragment 时，发生了一些奇怪的事情，可能它重复了该 fragment ，并且正在读取实际 fragment 后面的 fragment ，但没有从用户那里获取输入。

阅读此处了解 FragmentTransaction 的正确使用:https://developer.android.com/training/basics/fragments/fragment-ui

取自上面的文档，看看他们如何使用 FrameLayout作为容器。

XML:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Java:

public class MainActivity extends FragmentActivity {
@Override
public void onCreate(Bundle savedInstanceState?) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.news_articles);

    // Check that the activity is using the layout version with
    // the fragment_container FrameLayout
    if (findViewById(R.id.fragment_container) != null) {

        // However, if we're being restored from a previous state,
        // then we don't need to do anything and should return or else
        // we could end up with overlapping fragments.
        if (savedInstanceState != null) {
            return;
        }

        // Create a new Fragment to be placed in the activity layout
        HeadlinesFragment firstFragment = new HeadlinesFragment();

        // In case this activity was started with special instructions from an
        // Intent, pass the Intent's extras to the fragment as arguments
        firstFragment.setArguments(getIntent().getExtras());

        // Add the fragment to the 'fragment_container' FrameLayout
        getSupportFragmentManager().beginTransaction()
                .add(R.id.fragment_container, firstFragment).commit();
    }
}
}