java - 安卓/Java |抽屉导航的 TextView .setText 无法通过 SharedPreferences 工作

Question

我有一个 fragment ，允许用户更改其用户名，该用户名将显示在抽屉导航内的 TextView 中。 fragment “SettingsFragment”在 MainActivity 中膨胀。

SettingsFragment 有一个 EditText，用户可以在其中输入用户名和一个应用更改的按钮。抽屉导航是在 MainActivity 中创建的，因此我设置 SharedPreferences 将用户名发送到 MainActivity。然后，我继续使用 .setText(username) 更改抽屉导航中的 TextView，但是没有任何反应。 但是当我重新启动应用程序时，抽屉导航的 TextView 更改为用户在 EditText 中输入的实际用户名。

SettingsFragment.java:

public class SettingsFragment extends Fragment {


public SettingsFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View view = inflater.inflate(R.layout.fragment_settings, container, false);

    final TextInputEditText teiUserName = view.findViewById(R.id.teiUserName);
    final TextView tvEditTextSub = view.findViewById(R.id.tvEditTextSubstitute);
    Button btnApplyChanges = view.findViewById(R.id.btnApplyChanges);

    btnApplyChanges.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            final String user_name = String.valueOf(teiUserName.getText());

            tvEditTextSub.setText(user_name);

            SharedPreferences.Editor editor = getActivity().getSharedPreferences("myPrefs", MODE_PRIVATE).edit();
            editor.putString("name", user_name);
            editor.apply();

        }
    });

    return view;
}}

设置 fragment XML:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp"
tools:context="com.miguelpeachey.marketplacesimulator.Fragments.SettingsFragment">

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.TextInputEditText
        android:id="@+id/teiUserName"
        android:layout_width="248dp"
        android:layout_height="wrap_content"
        android:layout_above="@+id/btnApplyChanges"
        android:layout_marginBottom="28dp"
        android:text="User"
        android:textColorHint="#000" />

    <Button
        android:id="@+id/btnApplyChanges"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="28dp"
        android:background="#33993f"
        android:padding="12dp"
        android:text="Apply Changes"
        android:textColor="#FFF" />

</RelativeLayout>

MainActivity.java:

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

Fragment fragment;

SharedPreferences sharedPreferences;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Toolbar toolbar = findViewById(R.id.toolbar);
    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    NavigationView navigationView = findViewById(R.id.nav_view);
    View headerView = navigationView.getHeaderView(0);
    final TextView tvDrawerUsername = headerView.findViewById(R.id.tvDrawerUsername);
    setSupportActionBar(toolbar);

    sharedPreferences = getSharedPreferences("myPrefs", Context.MODE_PRIVATE);

    final String usernameID = sharedPreferences.getString("name", "User");

    if (drawer.isDrawerOpen(GravityCompat.START)) {
        tvDrawerUsername.setText(usernameID);
    }}

MainActivity.java 中还有更多代码，但无需包含它。

<小时/>

在MainActivity.java中，我也尝试过:

if (drawer.isDrawerOpen(GravityCompat.START)) {
        tvDrawerUsername.setText(usernameID);
    }

但重新启动应用程序后，它甚至没有更改抽屉导航的 TextView (tvDrawerUsername)。

<小时/>

总之，应用程序不会在单击按钮后立即更新 tvDrawerUsername，而只会在我重新启动应用程序后更新。

Answer 1

试试这个:

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

Fragment fragment;

SharedPreferences sharedPreferences;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    sharedPreferences = getSharedPreferences("myPrefs", Context.MODE_PRIVATE);Toolbar toolbar = findViewById(R.id.toolbar);
    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    NavigationView navigationView = findViewById(R.id.nav_view);
    View headerView = navigationView.getHeaderView(0);
    final TextView tvDrawerUsername = headerView.findViewById(R.id.tvDrawerUsername);

    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, null, "navigation_drawer_open", "navigation_drawer_close") {
            public void onDrawerClosed(View view) {
                super.onDrawerClosed(view);
                // Do whatever you want here
            }

            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);

                final String usernameID = sharedPreferences.getString("name", "User");
                tvDrawerUsername.setText(usernameID);
            }
        };
    drawer.addDrawerListener(toggle);
    toggle.syncState();
    setSupportActionBar(toolbar);
}