Fragments NullPointerException

Question

Heloo everyone! I have a problem with NavigationView and fragments. I created three fragments (as options in my NavigationView) when I click no matter which option there is a NullPointerException. I have no idea what is wrong :(

Here is activity_main.xml

<FrameLayout
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:id="@+id/fragmentsContainer"
   />

   <LinearLayout
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   tools:context = ".MainActivity">

  <android.support.design.widget.AppBarLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:theme="@style/AppTheme.AppBarOverlay"

      >
     <android.support.v7.widget.Toolbar
         android:id="@+id/toolbar"
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:popupTheme="@style/AppTheme.PopupOverlay"/>

     </android.support.design.widget.AppBarLayout>

  </LinearLayout>


   <android.support.design.widget.NavigationView
   android:layout_width="wrap_content"
   android:background="#aaaaaa"
   android:layout_height="match_parent"
   android:fitsSystemWindows="true"
   android:layout_gravity="start"
   android:id="@+id/navigationView"
   app:headerLayout="@layout/nav_header"
   app:menu="@menu/nav_menu"
   />

This is how I handle options:

navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener(){

        @Override
        public boolean onNavigationItemSelected(MenuItem item) {

            Fragment fragment=null;
            Class fragmentClass=null;

            int id = item.getItemId();

            switch(id){

                case R.id.aboutProgram:
                    fragmentClass = ProgramFragment.class;
                    break;

                case R.id.aboutAutor:
                    fragmentClass = AuthorFragment.class;
                    break;
                case R.id.Settings:
                    fragmentClass = SettingsFragment.class;
                    break;
                default:
                    fragmentClass = ProgramFragment.class;
            }

            try{
                fragment = (Fragment) fragmentClass.newInstance();
            }catch(Exception e){
                e.printStackTrace();
            }


           FragmentManager fragmentManager = getSupportFragmentManager();
         fragmentManager.beginTransaction().replace(R.id.fragmentsContainer,fragment).commit();



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

score 0 · Answer 1 · answered Aug 29 '16 at 20:26

Instead of managing the classes like that, try creating a new instance within the switch case like this:

Fragment fragment;
switch(id) {
   case R.id.aboutProgram:
   default:
      fragment = ProgramFragment.newInstance();
      break;
}

And so on down the line, then preform your transaction at the end.

Fragments NullPointerException

1 Answers1