我有奇怪的行为。每次我在活动中替换相同类型的片段(使用事务),新的片段实例被添加到片段列表。旧的实例在碎片管理器中保持活跃,并且在方向改变后在屏幕上可见(尽管不可点击)。
我的活动布局:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
——>
<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.cubesoft.zenfolio.moments.app.activity.MainActivity" >
<FrameLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</FrameLayout>
<fragment
android:id="@+id/navigation_drawer"
android:name="com.cubesoft.zenfolio.moments.app.fragment.NavigationDrawerFragment"
android:layout_width="@dimen/navigation_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
tools:layout="@layout/fragment_navigation_drawer" />
</android.support.v4.widget.DrawerLayout>
<fragment
android:id="@+id/fragmentConnectionStatus"
android:layout_width="match_parent"
android:layout_height="wrap_content"
class="com.cubesoft.zenfolio.fragment.ConnectionStatusFragment" />
改变片段的代码:
@Override
public void onNavigationDrawerItemSelected(int position) {
mCurrentDrawerPosition = position;
// update the main content by replacing fragments
List<Fragment> fragmemts = getSupportFragmentManager().getFragments();
switch (position) {
case 0:{
if ( getMyApplication().getGroupModel().getUsersCount() > 0 ) {
final Fragment fragment = UserSelectionFragment.newInstance();
final FragmentManager fragmentManager = getSupportFragmentManager();
//fragmentManager.popBackStack();
final FragmentTransaction tr = fragmentManager
.beginTransaction();
tr.replace(R.id.container, fragment);
tr.addToBackStack(null);
tr.setCustomAnimations(R.anim.abc_fade_in, R.anim.abc_fade_out);
tr.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
tr.commit();
} else {
final Fragment fragment = MomentsFragment.newInstance(mUsername);
final FragmentManager fragmentManager = getSupportFragmentManager();
//fragmentManager.popBackStack();
final FragmentTransaction tr = fragmentManager
.beginTransaction();
tr.replace(R.id.container, fragment);
//tr.setCustomAnimations(R.anim.abc_fade_in, R.anim.abc_fade_out);
tr.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
tr.addToBackStack(null);
tr.commit();
}
break;
}
case 1: {
final Fragment fragment = DownloadFragment.newInstance();
final FragmentManager fragmentManager = getSupportFragmentManager();
//fragmentManager.popBackStack();
final FragmentTransaction tr = fragmentManager
.beginTransaction();
tr.replace(R.id.container, fragment);
tr.addToBackStack(null);
tr.commit();
break;
}
/*case 2:
fragment = UserSelectionFragment.newInstance();
break;*/
}
}
UserSelectionFragment在几个方向改变后显示不正确,UserSelectionFragment的旧实例仍然在Fragment List中,但它们的View对象为null。
怎么了?
尝试删除
tr.addToBackStack(null);
对我来说,这将你的片段添加到backstack,这就是为什么它们被保存在你的片段列表中的原因。它们的视图是空的,因为它们在进入后台之前已经被销毁了。