I've my MainActivity with the following layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/lighter_gray"
tools:context="com.rewardsme.merchant.activities.MainActivity">
<FrameLayout
android:layout_marginTop="?attr/actionBarSize"
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
<LinearLayout
android:id="@+id/fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"></LinearLayout>
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="?android:attr/windowBackground"
app:menu="@menu/navigation" />
</LinearLayout>
I've got 3 tabs in the BottomNavigationView; they are 3 fragments. I want to keep the data and state of each fragment, during the transaction, like the Instagram application. I mean, if I load from database some data in Fragment A, I move to Fragment B and I come back to fragment A, I want to see the previously state. How Can I perform this?
**UPDATE**
这些代码行处理片段及其事务的选择。这些代码行在MainActivity中,newInstance是一个静态方法。 Fragment1,Fragment2和Fragment3是3个不同的片段,具有不同的布局和后端。正如我之前所说,我希望在使用应用程序时保持片段的状态,例如Instagram应用程序。
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_1:
changeFragment(getSupportFragmentManager(), Fragment1.newInstance(), R.id.container);
return true;
case R.id.navigation_2:
changeFragment(getSupportFragmentManager(), Fragment2.newInstance(), R.id.container);
case R.id.navigation_profile:
changeFragment(getSupportFragmentManager(),Fragment3.newInstance(), R.id.container);
return true;
}
return false;
}
};
public static void changeFragment(FragmentManager fragmentManager,
Fragment fragment, int frameId){
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(frameId, fragment);
transaction.commit();
}