I have a single Activity which hosts multiple fragments through a ViewPager. In the Activity's onCreate method I'm using the following code to change the ActionBar title:
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
if(getSupportActionBar() != null) {
getSupportActionBar().setTitle(getResources().getString(R.string.custom_title));
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
It works fine, but then I am unable to change it as soon as a Fragment becomes visible. In order to detect it I've implemented:
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser && getContext() != null) {
((MainActivity) getContext()).editActionBarTitle("new title");
}
}
And here's the definition for editActionBarTitle:
public void editActionBarTitle(String title) {
if(getSupportActionBar() != null) {
getSupportActionBar().setTitle(title);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
}
I can see that the method gets called as soon as a fragment becomes visible, but it has no effect on the ActionBar's title. What am I missing in order to edit the title correctly?
EDIT
I've also tried implementing addOnPageChangeListener in the viewPager, I can see that the method onPageSelected gets called but it has no effect on the title, here's an example on MainActivity:
public class MainActivity extends BaseActivity {
private NoScrollViewPager mViewPager;
private SectionsPagerAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Toolbar initialization
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
if(getSupportActionBar() != null) {
getSupportActionBar().setTitle("MainActivity");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
// ViewPager initialization
mViewPager = findViewById(R.id.containter);
setupViewPager();
}
private void setupViewPager() {
mAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mAdapter.addFragment(new Fragment1(), "Fragment 1");
mAdapter.addFragment(new Fragment2(), "Fragment 2");
mAdapter.addFragment(new Fragment3(), "Fragment 3");
mViewPager.setOffscreenPageLimit(mAdapter.getCount());
mViewPager.setAdapter(mAdapter);
// viewPager event listener
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { }
@Override
public void onPageSelected(int position) {
setTitle("fragment " + position);
if(getSupportActionBar() != null) {
getSupportActionBar().setTitle("fragment " + position);
}
}
@Override
public void onPageScrollStateChanged(int state) { }
});
}
public void setViewPager(int position) { mViewPager.setCurrentItem(position); }
}
This is the custom ViewPager class:
public class NoScrollViewPager extends ViewPager {
// Disable horizontal scrolling in ViewPager
private boolean isPagingEnabled = false;
public NoScrollViewPager(Context context) {
super(context);
}
public NoScrollViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
@SuppressLint("AndroidLintClickableViewAccessibility")
public boolean onTouchEvent(MotionEvent event) {
return this.isPagingEnabled && super.onTouchEvent(event);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
return this.isPagingEnabled && super.onInterceptTouchEvent(event);
}
public void setPagingEnabled(boolean b) {
this.isPagingEnabled = b;
}
}
And this is the custom Adapter class:
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
private FragmentManager fragmentManager;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
fragmentManager = fm;
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public Fragment getItem(int position) { return mFragmentList.get(position); }
@Override
public int getCount() { return mFragmentList.size(); }
@Override
public int getItemPosition(Object object) { return POSITION_NONE; }
}
