android - Android Studio：BottomNavigationView和片段之间的事务
问题描述
我正在尝试从 Jetpack实现BottomNavigationView
def nav_version = "2.0.0"
// Java language implementation
implementation "androidx.navigation:navigation-fragment:$nav_version"
implementation "androidx.navigation:navigation-ui:$nav_version"
第一个测试已完成，不包括下面显示的注释行，事务由库自动完成。
这样，我面临的问题是：如果我按100次底部菜单，我需要按100次后退按钮才能一直回到MainFragment。
第二个测试是取消注释注释行并且事务是硬编码的。
这样，我面临的问题是：片段内容相互重叠，我无法弄清楚我做错了什么。
由于第二次测试不成功，我再次运行没有下面显示的注释行（我删除它）的应用程序，但是库的自动事务（在第一次测试中经历）不再起作用。我的意思是只启动了 MainFragment，其他的都没有。
public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {
private static final String TAG = "debinf MainActivity";
//public static final String FRAGMENT_KEY = "fragment";
private BottomNavigationView bottomNavigationView;
private NavigationView navigationView;
private DrawerLayout drawerLayout;
private NavController navController;
private AppBarConfiguration appBarConfiguration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i(TAG, "onCreate: ");
bottomNavigationView = (BottomNavigationView) findViewById(R.id.main_bottomnav);
navigationView = (NavigationView) findViewById(R.id.main_sidebar);
drawerLayout = (DrawerLayout) findViewById(R.id.main_drawer);
setupNavigation();
// Fragment been created for the first time
/*if (getSupportFragmentManager().findFragmentByTag(FRAGMENT_KEY) == null) {
Log.i(TAG, "onCreate: First fragment been created: MainFragment()");
fragmentTransaction(new MainFragment());
}*/
}
private void setupNavigation() {
Log.i(TAG, "setupNavigation: ");
navController = Navigation.findNavController(this, R.id.main_fragment);
appBarConfiguration =
new AppBarConfiguration.Builder(navController.getGraph())
.setDrawerLayout(drawerLayout)
.build();
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
NavigationUI.setupWithNavController(bottomNavigationView, navController);
// Listener for bottomNavigation must be called after been setupWithNavController
bottomNavigationView.setOnNavigationItemSelectedListener(this);
}
/*private void fragmentTransaction(Fragment fragment) {
Log.i(TAG, "fragmentTransaction: Hardcoded Transaction");
getSupportFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
getSupportFragmentManager()
.beginTransaction()
.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out)
.replace(R.id.main_fragment, fragment, null)
.commit();
}*/
@Override
public void onBackPressed() {
Log.i(TAG, "onBackPressed: ");
if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
drawerLayout.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onSupportNavigateUp() {
Log.i(TAG, "onSupportNavigateUp: ");
return NavigationUI.navigateUp(navController, appBarConfiguration);
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
Log.i(TAG, "onNavigationItemSelected: ");
if (menuItem.getItemId() == R.id.mainFragment) {
Log.i(TAG, "onNavigationItemSelected: mainFrag");
//fragmentTransaction(new MainFragment()); // Hardcoded transaction
}
if (menuItem.getItemId() == R.id.shopFragment) {
Log.i(TAG, "onNavigationItemSelected: shopFrag");
//fragmentTransaction(new ShopFragment()); // Hardcoded transaction
}
if (menuItem.getItemId() == R.id.searchFragment) {
Log.i(TAG, "onNavigationItemSelected: searchFragment");
//fragmentTransaction(new SearchFragment()); // Hardcoded transaction
}
return true;
}
}
我需要做什么才能恢复 Jetpack 库的自动交易？
PS：除了上面代码中显示的内容外，我没有在其他任何地方更改任何代码。
编辑
下面是nav_graph.xml我想按一次返回按钮返回 MainFragment 并再次按返回按钮离开应用程序（第一个测试问题）。
我很感激任何帮助！
<navigation
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:id="@+id/mainnav_graph"
app:startDestination="@id/mainFragment">
<fragment
android:id="@+id/mainFragment"
android:name="com.aelecomerce.goodstag.MainFragment"
android:label="fragment_main"
tools:layout="@layout/fragment_main" />
<fragment
android:id="@+id/shopFragment"
android:name="com.aelecomerce.goodstag.ShopFragment"
android:label="fragment_shop"
tools:layout="@layout/fragment_shop" >
<action
android:id="@+id/openAddstoreFragment"
app:destination="@id/addstoreFragment"
app:enterAnim="@anim/nav_default_enter_anim"/>
<action
android:id="@+id/openBarcodeFragment"
app:destination="@id/barcodeFragment" />
</fragment>
<fragment
android:id="@+id/searchFragment"
android:name="com.aelecomerce.goodstag.SearchFragment"
android:label="fragment_search"
tools:layout="@layout/fragment_search" />
<fragment
android:id="@+id/addstoreFragment"
android:name="com.aelecomerce.goodstag.AddstoreFragment"
android:label="fragment_addstore"
tools:layout="@layout/fragment_addstore" />
<fragment
android:id="@+id/barcodeFragment"
android:name="com.aelecomerce.goodstag.BarcodeFragment"
android:label="fragment_barcode"
tools:layout="@layout/fragment_barcode" />
</navigation>
下面是 BottomNavigationView 的菜单
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:id="@id/mainFragment"
android:title="Home"
android:icon="@android:drawable/stat_sys_phone_call_on_hold"
android:menuCategory="secondary"/>
<item
android:id="@id/shopFragment"
android:title="Shop"
android:icon="@android:drawable/stat_sys_phone_call_on_hold"
android:menuCategory="secondary"/>
<item
android:id="@id/searchFragment"
android:title="Search"
android:icon="@android:drawable/stat_sys_phone_call_on_hold"
android:menuCategory="secondary"/>
</menu>
下面是main_activity.xml
<androidx.drawerlayout.widget.DrawerLayout
android:id="@+id/main_drawer"
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=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/main_fragment"
android:layout_width="0dp"
android:layout_height="0dp"
android:name="androidx.navigation.fragment.NavHostFragment"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="@id/main_bottomnav"
app:defaultNavHost="true"
app:navGraph="@navigation/mainnav_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/main_bottomnav"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="@menu/main_navmenu"
android:background="@color/colorAccent"
app:itemIconTint="@drawable/botton_item_color"
app:itemTextColor="@drawable/botton_item_color">
</com.google.android.material.bottomnavigation.BottomNavigationView>
</androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/main_sidebar"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:menu="@menu/main_sidebarmenu"/>
</androidx.drawerlayout.widget.DrawerLayout>
解决方案
删除线
bottomNavigationView.setOnNavigationItemSelectedListener(this);
因为那是覆盖OnNavigationItemSelectedListener设置的setupWithNavController()。
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