所以我有一个Settings片段，它的onCreateView被多次调用。我有ViewPager，它在片段的布局中，点击工具栏选项菜单中的设置图标即可启动片段。
我不能只是将ViewPager移到活动中，因为我希望能够滑动回上一个片段。
此外，我试着用去除背面的碎片
for(int i=0;i< Objects.requireNonNull(fm).getBackStackEntryCount();++i){
fm.popBackStackImmediate();
}
但这一点帮助都没有。
片段代码：
public class SettingsFragment extends Fragment {
public SettingsFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Deprecated
@Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container,
Bundle savedInstanceState) {
final View rootview = inflater.inflate(R.layout.fragment_settings, container, false);
final CustomViewPager viewPager=rootview.findViewById(R.id.SettingsFragmentViewPager);
viewPager.setAdapter(new Adapter(getFragmentManager()));
viewPager.setOffscreenPageLimit(2);
viewPager.setCurrentItem(1);
viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
if (position == 0) {
viewPager.setPagingEnabled(false);
FragmentManager fm=getFragmentManager();
for(int i=0;i< Objects.requireNonNull(fm).getBackStackEntryCount();++i){
fm.popBackStackImmediate();
}
viewPager.removeOnPageChangeListener(this);
}
}
});
return rootview;
}
片段的xml:
<androidx.constraintlayout.widget.ConstraintLayout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="#fff" android:animationCache="true"
android:id="@+id/SettingsFragmentContainer"
android:clickable="true"
android:drawingCacheQuality="high" android:focusable="true">
<androidx.appcompat.widget.Toolbar
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:theme="?attr/actionBarTheme"
android:minHeight="?attr/actionBarSize" app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:id="@+id/SettingsActivityToolbar" app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"/>
<TextView
android:text="Settings"
android:layout_width="65dp"
android:layout_height="23dp" app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent" android:layout_marginTop="18dp"
app:layout_constraintEnd_toEndOf="parent" android:id="@+id/Settings_textview"
android:textAppearance="@style/ActionBar.nameText"/>
<ImageButton
android:layout_width="46dp"
android:layout_height="34dp" app:srcCompat="@drawable/settings_icon_back"
android:id="@+id/backPressButton"
android:rotation="180" android:backgroundTint="#fff"
android:background="@null"
app:layout_constraintStart_toStartOf="@+id/SettingsActivityToolbar"
android:layout_marginStart="2dp" app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="16dp" android:onClick="click" android:drawingCacheQuality="high"/>
<TextView
android:text=""
android:layout_width="0dp"
android:layout_height="0.1dp" app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent" android:id="@+id/linebreak1" android:layout_marginTop="10dp"
app:layout_constraintTop_toBottomOf="@+id/backPressButton" android:background="#A1A8AC"/>
<TextView
android:layout_width="0dp"
android:layout_height="0.1dp" android:id="@+id/linebreak2"
android:background="#A1A8AC"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent" android:layout_marginTop="7dp"
app:layout_constraintTop_toBottomOf="@+id/switch4"/>
<Switch
android:text="Test Test"
android:layout_width="0dp"
android:layout_height="47dp" android:id="@+id/switch4"
android:textAppearance="@style/ActionBar.nameText" app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="25dp" android:layout_marginEnd="25dp"
app:layout_constraintEnd_toEndOf="parent" android:thumbTint="@drawable/switch_thumb_selector"
android:trackTint="@drawable/switch_track_selector" android:layout_marginTop="18dp"
app:layout_constraintTop_toBottomOf="@+id/backPressButton" tools:ignore="UseSwitchCompatOrMaterialXml"/>
<TextView
android:layout_width="0dp"
android:layout_height="67dp" android:id="@+id/update"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:clickable="true"
android:textAppearance="@style/ActionBar.nameText" app:layout_constraintHorizontal_bias="0.0"
android:background="?attr/selectableItemBackground" android:layout_marginTop="16dp"
app:layout_constraintTop_toBottomOf="@+id/switch4" android:onClick="onClickUpdate"
android:focusable="true"/>
<TextView
android:text="test test"
android:layout_width="wrap_content"
android:clickable="true"
android:layout_height="0dp" android:id="@+id/enter_version"
app:layout_constraintTop_toTopOf="@+id/update"
android:layout_marginTop="36dp" android:layout_marginEnd="206dp"
app:layout_constraintEnd_toEndOf="@+id/update" android:focusable="true"/>
<TextView
android:text="Check Update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:clickable="true"
android:id="@+id/update_textview"
android:textAppearance="@style/ActionBar.nameText" android:layout_marginEnd="228dp"
app:layout_constraintEnd_toEndOf="@+id/update" app:layout_constraintTop_toTopOf="@+id/update"
android:layout_marginTop="10dp" android:focusable="true"/>
<com.testapp.test2.CustomViewPager
android:layout_width="0dp"
android:layout_height="0dp" app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" app:layout_constraintVertical_bias="0.58000004"
app:layout_constraintStart_toStartOf="parent" android:id="@+id/SettingsFragmentViewPager"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
我用于ViewPager:的适配器
public class Adapter extends FragmentStatePagerAdapter {
public Adapter(FragmentManager fragmentManager){
super(fragmentManager,BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
}
@NotNull
@Override
public Fragment getItem(int position) {
if(position==0){
return new BlankFragment();
}
if(position==1){
return new SettingsFragment();
}
return null;
}
@Override
public int getCount() {
return 2;
}
}
我看到在我的适配器中，我也返回了SettingsFragment。有没有办法返回我单击工具栏中的设置按钮时创建的片段？
顺便说一句，我用这个添加片段：
@Override
public boolean onOptionsItemSelected(MenuItem item){
switch(item.getItemId()){
case R.id.updateId:
Log.d("MAIN ACTIVITY---","ADDING FRAGMENT...");
FragmentTransaction ft=getSupportFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.push_right_in,0);
ft.add(R.id.MainActivityConstraint,new SettingsFragment());
ft.commit();
Log.d("ACTIVITY---","Fragment added...");
break;
}
}
我决定使用一个名为swipebacklayout的外部库，而不是ViewPager。你可以在这里查看。https://github.com/gongwen/swipebacklayout