Java – How do I change the ActionBar title from the fragment class in Android Studio?

Please help me…

I use the built-in Navigation Drawer Activity in Android Studio

What I want is to change the column title from fragment…

Here is my code

The main activity .java

package com.example.administrator.mosbeau;

import android.app.Activity;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;

public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

/**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

/**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;

Boolean InternetAvailable = false;
    Seocnd detectconnection;

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

detectconnection = new Seocnd(this);
        InternetAvailable = detectconnection. InternetConnecting();
        if (InternetAvailable) {
        } else {
            NointernetFragment fragment = new NointernetFragment();
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.container, fragment)
                    .commit();
        }

mNavigationDrawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

 Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }

@Override
    public void onNavigationDrawerItemSelected(int position) {
         update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
            case 0:
                fragment = new HomeFragment();
                break;
            case 1:
                fragment = new AccountFragment();
                break;
        }
        if (fragment == null) {
            fragment = new HomeFragment();
        }
         update the main content by replacing fragments
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.container, fragment)
                .commit();
    }

public void onSectionAttached(int number) {
        switch (number) {
            case 1:
                mTitle = getString(R.string.title_home);
                break;
            case 2:
                mTitle = getString(R.string.title_account);
                break;
        }
    }

public void restoreActionBar () {
        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode( ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled( true );
        actionBar.setTitle( mTitle );
    }

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
             Only show items in the action bar relevant to this screen
             if the drawer is not showing. Otherwise, let the drawer
             decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }

@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);
    }

/**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

/**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

public PlaceholderFragment() {
        }

@Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }

@Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            ((MainActivity) activity).onSectionAttached(
                    getArguments().getInt(ARG_SECTION_NUMBER));
        }

}

}

NavigationDrawerFragment.java

package com.example.administrator.mosbeau;

import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

/**
 * Fragment used for managing interactions for and presentation of a navigation drawer.
 * See the <a href="https://developer.android.com/design/patterns/navigation-drawer.html#Interaction">
 * design guidelines</a> for a complete explanation of the behaviors implemented here.
 */
public class NavigationDrawerFragment extends Fragment {

/**
     * Remember the position of the selected item.
     */
    private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";

/**
     * Per the design guidelines, you should show the drawer on launch until the user manually
     * expands it. This shared preference tracks this.
     */
    private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";

/**
     * A pointer to the current callbacks instance (the Activity).
     */
    private NavigationDrawerCallbacks mCallbacks;

/**
     * Helper component that ties the action bar to the navigation drawer.
     */
    private ActionBarDrawerToggle mDrawerToggle;

private DrawerLayout mDrawerLayout;
    private ListView mDrawerListView;
    private View mFragmentContainerView;

private int mCurrentSelectedPosition = 0;
    private boolean mFromSavedInstanceState;
    private boolean mUserLearnedDrawer;

public NavigationDrawerFragment() {
    }

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

 Read in the flag indicating whether or not the user has demonstrated awareness of the
         drawer. See PREF_USER_LEARNED_DRAWER for details.
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
        mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);

if (savedInstanceState != null) {
            mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
            mFromSavedInstanceState = true;
        }

 Select either the default item (0) or the last selected item.
        selectItem(mCurrentSelectedPosition);
    }

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
         Indicate that this fragment would like to influence the set of actions in the action bar.
        setHasOptionsMenu(true);
    }

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mDrawerListView = (ListView) inflater.inflate(
                R.layout.fragment_navigation_drawer, container, false);
        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });
        mDrawerListView.setAdapter(new ArrayAdapter<String>(
                getActionBar().getThemedContext(),
                android. R.layout.simple_list_item_activated_1,
                android. R.id.text1,
                new String[]{
                        getString(R.string.title_home),
                        getString(R.string.title_account),
                }));
        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return mDrawerListView;
    }

public boolean isDrawerOpen() {
        return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
    }

/**
     * Users of this fragment must call this method to set up the navigation drawer interactions.
     *
     * @param fragmentId   The android:id of this fragment in its activity's layout.
     * @param drawerLayout The DrawerLayout containing this fragment's UI.
     */
    public void setUp(int fragmentId, DrawerLayout drawerLayout) {
        mFragmentContainerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;

 set a custom shadow that overlays the main content when the drawer opens
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
         set up the drawer's list view with items and click listener

ActionBar actionBar = getActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        actionBar.setHomeButtonEnabled(true);

 ActionBarDrawerToggle ties together the the proper interactions
         between the navigation drawer and the action bar app icon.
        mDrawerToggle = new ActionBarDrawerToggle(
                getActivity(),                    /* host Activity */
                mDrawerLayout,                    /* DrawerLayout object */
                R.string.navigation_drawer_open,  /* "open drawer" description for accessibility */
                R.string.navigation_drawer_close  /* "close drawer" description for accessibility */
        ) {
            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                if (!isAdded()) {
                    return;
                }

getActivity().supportInvalidateOptionsMenu();  calls onPrepareOptionsMenu()
            }

@Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                if (!isAdded()) {
                    return;
                }

if (!mUserLearnedDrawer) {
                     The user manually opened the drawer; store this flag to prevent auto-showing
                     the navigation drawer automatically in the future.
                    mUserLearnedDrawer = true;
                    SharedPreferences sp = PreferenceManager
                            .getDefaultSharedPreferences(getActivity());
                    sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
                }

getActivity().supportInvalidateOptionsMenu();  calls onPrepareOptionsMenu()
            }
        };

 If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
         per the navigation drawer design guidelines.
        if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
            mDrawerLayout.openDrawer(mFragmentContainerView);
        }

 Defer code dependent on restoration of previous instance state.
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });

mDrawerLayout.setDrawerListener(mDrawerToggle);
    }

private void selectItem(int position) {
        mCurrentSelectedPosition = position;
        if (mDrawerListView != null) {
            mDrawerListView.setItemChecked(position, true);
        }
        if (mDrawerLayout != null) {
            mDrawerLayout.closeDrawer(mFragmentContainerView);
        }
        if (mCallbacks != null) {
            mCallbacks.onNavigationDrawerItemSelected(position);
        }
    }

@Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallbacks = (NavigationDrawerCallbacks) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
        }
    }

@Override
    public void onDetach() {
        super.onDetach();
        mCallbacks = null;
    }

@Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
    }

@Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
         Forward the new configuration the drawer toggle component.
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

@Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
         If the drawer is open, show the global app actions in the action bar. See also
         showGlobalContextActionBar, which controls the top-left area of the action bar.
        if (mDrawerLayout != null && isDrawerOpen()) {
            inflater.inflate(R.menu.global, menu);
            showGlobalContextActionBar();
        }
        super.onCreateOptionsMenu(menu, inflater);
    }

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }

if (item.getItemId() == R.id.action_example) {
            Toast.makeText(getActivity(), "Example action.", Toast.LENGTH_SHORT).show();
            return true;
        }

return super.onOptionsItemSelected(item);
    }

/**
     * Per the navigation drawer design guidelines, updates the action bar to show the global app
     * 'context', rather than just what's in the current screen.
     */
    private void showGlobalContextActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setTitle(R.string.app_name);
    }

private ActionBar getActionBar() {
        return ((ActionBarActivity) getActivity()).getSupportActionBar();
    }

/**
     * Callbacks interface that all activities using this fragment must implement.
     */
    public static interface NavigationDrawerCallbacks {
        /**
         * Called when an item in the navigation drawer is selected.
         */
        void onNavigationDrawerItemSelected(int position);
    }
}

I want to change the column title in every fragment shown

Home fragment .java

package com.example.administrator.mosbeau;

import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by Administrator on 9/7/2015.
 */
public class HomeFragment extends Fragment {

Boolean InternetAvailable = false;
    Seocnd detectconnection;

@Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.homelayout, container, false);

detectconnection = new Seocnd(getActivity());
        InternetAvailable = detectconnection. InternetConnecting();
        if (InternetAvailable) {
        } else {
            NointernetFragment fragment = new NointernetFragment();
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.container, fragment)
                    .commit();
        }

return rootView;
    }

}

Edit: Please help me…

Depending on your code, you don’t need to change the action bar title in the fragment

You can change it in your switch case

@Override
public void onNavigationDrawerItemSelected(int position) {
     update the main content by replacing fragments
    Fragment fragment = null;
    String title = "";

switch (position) {
        case 0:
            fragment = new HomeFragment();
            title="Home";
            break;
        case 1:
            fragment = new AccountFragment();
            title="Accounts";
            break;
    }
    if (fragment == null) {
        fragment = new HomeFragment();
    }
     update the main content by replacing fragments
    FragmentManager fragmentManager = getFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.container, fragment)
            .commit();

getSupportActionBar().setTitle(title);
}

Even if you want to change the actionbar from the fragment using the interface
Create an interface in the fragment
Implementing an Interface in an Activity
When you want to use the callback to call the interface function in the Activity to change the actionbar