How to change fragment with the Bottom Navigation Activity?

Question

I created a new project with the "Bottom Navigation Activity":

This is the generated code:

package com.aaron.waller.mrpolitik;  import android.os.Bundle; import android.support.annotation.NonNull; import android.support.design.widget.BottomNavigationView; import android.support.v7.app.AppCompatActivity; import android.view.MenuItem; import android.widget.TextView;  public class MainActivity extends AppCompatActivity {      private TextView mTextMessage;      private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener             = new BottomNavigationView.OnNavigationItemSelectedListener() {          @Override         public boolean onNavigationItemSelected(@NonNull MenuItem item) {             switch (item.getItemId()) {                 case R.id.navigation_home:                     mTextMessage.setText(R.string.title_home);                 case R.id.navigation_dashboard:                     mTextMessage.setText(R.string.title_dashboard);                 case R.id.navigation_notifications:                     mTextMessage.setText(R.string.title_notifications);             }             return true;         }      };      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          mTextMessage = (TextView) findViewById(R.id.message);         BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);         navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);     }  } 

How can I change to new Fragments with the Bottom Bar? For example I have 3 Fragments: Fragment1 Fragment2 and Fragment3 And I want to change to them with the 3 buttons from the Bottom Bar. Also I want that I can switch the Fragments by swiping my finger left and right how can I do that?

Answer 1

The way I would do it is, I would first add three methods similar to this one (each for a single fragment. Replace the layout name and the fragment object to the appropriate fragment that is being switched to):

public void switchToFragment1() {     FragmentManager manager = getSupportFragmentManager();     manager.beginTransaction().replace(R.id.your_fragment_layout_name, new Fragment1()).commit(); } 

So your switch statement would end up looking like this:

        switch (item.getItemId()) {             case R.id.navigation_home:                 mTextMessage.setText(R.string.title_home);                 switchToFragment1();                 break;              case R.id.navigation_dashboard:                 mTextMessage.setText(R.string.title_dashboard);                                     switchToFragment2();                 break;              case R.id.navigation_notifications:                 mTextMessage.setText(R.string.title_notifications);                                      switchToFragment3();                 break;         } 

As for switching the fragments by swiping to the sides, I believe you would need a ViewPager.

Answer 2

It's pretty "simple".

1. Create your Fragments. Let's say we want 3 fragments; FragmentA, FragmentB and FragmentC with FragmentA being the first Fragment we want on the BottomNavigationView.

2. In your Activity, go to the onNavigationItemSelected method and change the content to this:

    private BottomNavigationView.OnNavigationItemSelectedListener      mOnNavigationItemSelectedListener        = new BottomNavigationView.OnNavigationItemSelectedListener(){     @Override    public boolean onNavigationItemSelected(@NonNull MenuItem item) {      switch (item.getItemId()) {         case R.id.frag_a:             currentFragment = new FragmentA();             ft = getSupportFragmentManager().beginTransaction();             ft.replace(R.id.content, currentFragment);             ft.commit();             return true;         case R.id.frag_b:             currentFragment = new FragmentB();             ft = getSupportFragmentManager().beginTransaction();             ft.replace(R.id.content, currentFragment);             ft.commit();             return true;         case R.id.frag_c:             currentFragment = new FragmentC();             ft = getSupportFragmentManager().beginTransaction();             ft.replace(R.id.content, currentFragment);             ft.commit();             return true;     }      return false;  }  }; 

3. In your onCreate()method, do this:

     @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_client_profile);     ft = getSupportFragmentManager().beginTransaction();     currentFragment = new FragmentA();     ft.replace(R.id.content, currentFragment);     ft.commit();      BottomNavigationView navigation = (BottomNavigationView)       findViewById(R.id.navigation); navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);   } 

If you do not add FragmentA in the onCreate(), the activity is blank when you first launch it.

If you are wondering what R.id.content refers to, it is the Id of the Framelayout in your activity's layout. It initially contains a TextView, delete the TextView so it looks like this:

<FrameLayout     android:id="@+id/content"     android:layout_width="match_parent"     android:layout_height="0dp"     android:layout_weight="1"/> 

Finally, ft and currentFragment are defined like this:

Fragment currentFragment = null; FragmentTransaction ft; 

Not sure about elegance, but this works.