How to switch to another activity as well as change the fragment which is in that Activity?

jashdf :

I have a main_activity with 3 different Fragment and a SlideActivity. I could make transactions among 3 fragments successfully in my MainActivity.

Now I add 1 button in the MainActivity and it will open the SlideActivity. On the SlideActivity, there are 3 buttons in the navigation bar to switch to each different fragments which I already created.

The problem is when I click the list button in the navigation, an error comes out shows that

No view found for id 0x7f080052 (com.example.learnfragment:id/fragment_container) for fragment fragment_main{e1acaf7 #0 id=0x7f080052}

It seems that it cannot find the FrameLayout ID by R.id. and I believe because the navigation buttons are in the SlideActivity and it cannot find the ID which is in the MainActivity.

But how should I do for switching back to the MainActivity as well as changing different fragment?

Here's the navigation_slide_activity.xml

<include
    layout="@layout/app_bar_slide"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<android.support.design.widget.NavigationView
    android:id="@+id/nav_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/nav_header_slide"
    app:menu="@menu/activity_slide_drawer" />

The Navigation_Slide_Activity.java:

public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        // Navigate back to the Main Fragment
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.fragment_container, new fragment_main());
        ft.commit();
    }
}

And the main_activity.xml:

<FrameLayout
    android:id="@+id/fragment_container"
    android:layout_width="392dp"
    android:layout_height="496dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp" />

Finally, the MainActivity.java

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // Create Fragment
    if(savedInstanceState == null){
        getSupportFragmentManager().beginTransaction().add(
                R.id.fragment_container,
                new fragment_main()).commit();
    }
}

Reaz Murshed :

Get a public static variable in your MainActivity.

public static int FRAGMENT_TO_BE_LOADED = 0;

Now from the SlideActivity, set the variable to a number (e.g. 3, that is you want to move to the third fragment when you are returning to your MainActivity.

public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        MainActivity.FRAGMENT_TO_BE_LOADED = 3; 
        finish();
    }
}

Now in your MainActivity, you need to have an onResume function which will check the variable and load the fragment accordingly.

@Override
protected void onResume() {
    super.onResume();

    if(FRAGMENT_TO_BE_LOADED == 1) loadFragment1();
    else if(FRAGMENT_TO_BE_LOADED == 2) loadFragment2();
    else if(FRAGMENT_TO_BE_LOADED == 3) loadFragment3();
}

Hope that solves your problem.