VISHNU VISHNU - 2 months ago 18
Android Question

Other Fragment is viewed above the current fragment changes on rotation with android studio navigation drawer template

Thank you for spending time on my qeustion. In my app I am using android studio navigation drawer template.
But the problem is that, when I rotate the phone, the previous fragment's layout is shown above the current fragment.

public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

Fragment fragment = null;
Class fragmentClass = null;


/* if (savedInstanceState == null){
try{
fragment = (Fragment) fragmentClass.newInstance();
}catch (Exception e){
e.printStackTrace();
}
}*/
fragment = new Login();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.fragment, fragment);
fragmentTransaction.commit();




FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});

DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();

NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}

@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();

//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}

return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {

// Handle navigation view item clicks here.
int id = item.getItemId();
Fragment fragment =null ;
Class fragmentClas = null;

if (id == R.id.nav_camera) {
// Handle the camera action
fragment = new Attendance();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment, fragment);
fragmentTransaction.commit();
} else if (id == R.id.nav_gallery) {

fragment = new AddStudent();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment, fragment);
fragmentTransaction.commit();
} else if (id == R.id.nav_slideshow) {

} else if (id == R.id.nav_manage) {

} else if (id == R.id.nav_share) {

} else if (id == R.id.nav_send) {

}

/* FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();*/

DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}


}

Answer

When you rotate the device, the activity saves its current state and keeps the current fragment then it's destroyed and recreated i.e. onCreate() is called again. You had one fragment before it's destroyed and now it added another in the new call to onCreate() that's why you have 2 fragments. To fix this you should check first if the savedInstanceState parameter in onCreate() is null i.e. it's the first creation of activity not just being restarted due to rotation change or anything, then decide to add the fragment or not instead of adding to whenever the activity calls onCreate()

if(savedInstanceState == null) {
    // Add the fragment because it's normal creation
    fragment = new Login();
    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.add(R.id.fragment, fragment);
    fragmentTransaction.commit();
}
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