我发现它是好多了在代码中添加同样适用于双窗格的片段。
因此,不要使用<fragment>
,还可以使用<FrameLayout>
也适用于双窗格 XML。
/layout-w900dp/activity_main.xml:
<LinearLayout
android:id="@+id/dual_pane"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="@+id/master_dual"
android:layout_width="@dimen/master_frag_width"
android:layout_height="match_parent"/>
<FrameLayout
android:id="@+id/detail_dual"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
通过这种方式,您可以使用just onemasterFragment 和 DetailFragment 的实例,因此您不会遇到同一片段有多个实例的问题。
为了做到这一点,在OnCreate
您需要将片段添加到容器中,与旧容器分离:
mDualPane = findViewById(R.id.dual_pane)!=null;
if (savedInstanceState!=null) {
mLastSinglePaneFragment = savedInstanceState.getString("lastSinglePaneFragment");
}
FragmentManager fm = getSupportFragmentManager();
if (!mDualPane && fm.findFragmentById(R.id.single_pane)==null) {
MasterFragment masterFragment = getDetatchedMasterFragment(false);
fm.beginTransaction().add(R.id.single_pane, masterFragment, MASTER_FRAGMENT).commit();
if (mLastSinglePaneFragment==DETAIL_FRAGMENT) {
openSinglePaneDetailFragment();
}
}
if (mDualPane && fm.findFragmentById(R.id.master_dual)==null) {
MasterFragment masterFragment = getDetatchedMasterFragment(true);
fm.beginTransaction().add(R.id.master_dual, masterFragment, MASTER_FRAGMENT).commit();
}
if (mDualPane && fm.findFragmentById(R.id.detail_dual)==null) {
DetailFragment detailFragment = getDetatchedDetailFragment();
fm.beginTransaction().add(R.id.detail_dual, detailFragment, DETAIL_FRAGMENT).commit();
}
使用这些函数:
public static final String MASTER_FRAGMENT = "MASTER_FRAGMENT";
public static final String DETAIL_FRAGMENT = "DETAIL_FRAGMENT";
private MasterFragment getDetatchedMasterFragment(boolean popBackStack) {
FragmentManager fm = getSupportFragmentManager();
MasterFragment masterFragment = getSupportFragmentManager().findFragmentByTag(MASTER_FRAGMENT);
if (masterFragment == null) {
masterFragment = new MasterFragment();
} else {
if (popBackStack) {
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
fm.beginTransaction().remove(masterFragment).commit();
fm.executePendingTransactions();
}
return masterFragment;
}
private DetailFragment getDetatchedDetailFragment() {
FragmentManager fm = getSupportFragmentManager();
DetailFragment detailFragment = getSupportFragmentManager().findFragmentByTag(DETAIL_FRAGMENT);
if (detailFragment == null) {
detailFragment = new DetailFragment();
} else {
fm.beginTransaction().remove(detailFragment).commit();
fm.executePendingTransactions();
}
return detailFragment;
}
private void openSinglePaneDetailFragment() {
FragmentManager fm = getSupportFragmentManager();
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
DetailFragment detailFragment = getDetatchedDetailFragment();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.single_pane, detailFragment, DETAIL_FRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}