D.Y D.Y - 6 months ago 115
Java Question

How can I change action bar title with different style in different fragments?

I am trying to change my 2 fragments action bar's with different titles. However, I am getting variable

fragment
might not have been initialized error in these lines:

ProfileFragment fragment = (ProfileFragment) fragment.get(0)
;

StartingTestFragment fragment2 = (StartingTestFragment) fragment2.get(0);


in
CombineFragmentActivity
in
onPageSelected
method.Thanks for helps.

CombineFragmentActivity.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.Gravity;

import java.util.ArrayList;
import java.util.List;
import java.util.Vector;

public class CombineFragmentActivity extends AppCompatActivity {
private PagerAdapter mPagerAdapter;

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.combine_fragment_activity);
initialisePaging();
}

private void initialisePaging() {

List<Fragment> fragments = new ArrayList<>();
fragments.add(new StartingTestFragment());
fragments.add(new ProfileFragment());
mPagerAdapter = new PagerAdapter1(this.getSupportFragmentManager(),fragments);

ViewPager pager = (ViewPager)findViewById(R.id.viewpager);
pager.setAdapter(mPagerAdapter);

pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener(){
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

}

@Override
public void onPageSelected(int position) {
if(position == 0) {
ProfileFragment fragment = (ProfileFragment) fragment.get(0);
fragment.setActionBarTitle("Profil");
} else {
StartingTestFragment fragment2 = (StartingTestFragment) fragment2.get(0);
fragment2.setActionBarTitle("Anasayfa");
}

}

@Override
public void onPageScrollStateChanged(int state) {

}

});
}
}


ProfileFragment.java

import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.util.TypedValue;
import android.view.Gravity;
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.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;


public class ProfileFragment extends Fragment implements AdapterView.OnItemSelectedListener {
public ProfileFragment() {
// Required empty public constructor
}


public static ProfileFragment newInstance() {
ProfileFragment fragment = new ProfileFragment();
return fragment;
}

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

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_profile, container, false);

}

public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);

Typeface ubuntu_MI = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-MI.ttf");
Typeface ubuntu_L = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-L.ttf");
Typeface ubuntu_R = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-R.ttf");


/**
* Be carefull when trying to find a view element from a layout if the name is already defined in any layout
* AndroidStudio will not hint an error and you will end up with with ugly null pointer error
TextView question = (TextView) view.findViewById(R.id.textView7);
question.setTypeface(ubuntu_R);
TextView info = (TextView) view.findViewById(R.id.textView6);
info.setTypeface(ubuntu_R);

*/


}
public void setActionBarTitle(String title) {
Typeface ubuntu_MI = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-MI.ttf");
// Get the ActionBar
android.support.v7.app.ActionBar ab = ((AppCompatActivity)getActivity()).getSupportActionBar();


// Create a TextView programmatically.
TextView tv = new TextView(getActivity());

// Create a LayoutParams for TextView
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.MATCH_PARENT, // Width of TextView
RelativeLayout.LayoutParams.WRAP_CONTENT); // Height of TextView

// Apply the layout parameters to TextView widget
tv.setLayoutParams(lp);

// Set text to display in TextView
// This will set the ActionBar title text
tv.setText(title);

// Set the text color of TextView
// This will change the ActionBar title text color
tv.setTextColor(Color.parseColor("#FFF5EE"));

// Center align the ActionBar title
tv.setGravity(Gravity.CENTER_HORIZONTAL);

// Set the serif font for TextView text
// This will change ActionBar title text font
tv.setTypeface(ubuntu_MI);

// Underline the ActionBar title text
// tv.setPaintFlags(tv.getPaintFlags()| Paint.UNDERLINE_TEXT_FLAG);

// Set the ActionBar title font size
tv.setTextSize(TypedValue.COMPLEX_UNIT_DIP,24);

// Display a shadow around ActionBar title text
//tv.setShadowLayer(
// 1.f, // radius
// 2.0f, // dx
// 2.0f, // dy
// Color.parseColor("#FF8C00") // shadow color
//);

// Set the ActionBar display option
ab.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);

// Finally, set the newly created TextView as ActionBar custom view
ab.setCustomView(tv);
}
public boolean onOptionsItemSelected(MenuItem item) {
//Action Bar' daki settings kısmına basıldığında ne yapacağını söylüyoruz.
if(item.getItemId() == R.id.settings){
Toast.makeText(getActivity(), "Ayarlara basıldı", Toast.LENGTH_SHORT).show();
}

return super.onOptionsItemSelected(item);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
super.onCreateOptionsMenu(menu, inflater);
inflater.inflate(R.menu.menu_profile_activity, menu);

}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

}

@Override
public void onNothingSelected(AdapterView<?> parent) {

}

}


StartingTestFragment.java

import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.RelativeLayout;
import android.widget.Spinner;
import android.widget.TextView;


public class StartingTestFragment extends Fragment implements AdapterView.OnItemSelectedListener {
private Spinner spinner;
ArrayAdapter<CharSequence> adapter;



public StartingTestFragment() {
// Required empty public constructor
}


public static StartingTestFragment newInstance() {
StartingTestFragment fragment = new StartingTestFragment();
return fragment;
}

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

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_startingtest, container, false);
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
spinner = (Spinner)view.findViewById(R.id.spinner);
adapter = ArrayAdapter.createFromResource(getActivity(),R.array.simple_spinner_dropdown_item,R.layout.spinner_item);
adapter.setDropDownViewResource(R.layout.spinner_dropdown_item);

spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(this);


Typeface ubuntu_L = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-L.ttf");
Typeface ubuntu_R = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-R.ttf");

TextView info = (TextView) view.findViewById(R.id.textView6);
TextView question = (TextView) view.findViewById(R.id.textView7);

info.setTypeface(ubuntu_R);
question.setTypeface(ubuntu_R);



}
public void setActionBarTitle(String title) {
Typeface ubuntu_MI = Typeface.createFromAsset(getActivity().getAssets(),"Ubuntu-MI.ttf");
// Get the ActionBar
android.support.v7.app.ActionBar ab = ((AppCompatActivity)getActivity()).getSupportActionBar();


// Create a TextView programmatically.
TextView tv = new TextView(getActivity());

// Create a LayoutParams for TextView
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.MATCH_PARENT, // Width of TextView
RelativeLayout.LayoutParams.WRAP_CONTENT); // Height of TextView

// Apply the layout parameters to TextView widget
tv.setLayoutParams(lp);

// Set text to display in TextView
// This will set the ActionBar title text
tv.setText(title);

// Set the text color of TextView
// This will change the ActionBar title text color
tv.setTextColor(Color.parseColor("#FFF5EE"));

// Center align the ActionBar title
tv.setGravity(Gravity.CENTER_HORIZONTAL);

// Set the serif font for TextView text
// This will change ActionBar title text font
tv.setTypeface(ubuntu_MI);

// Underline the ActionBar title text
// tv.setPaintFlags(tv.getPaintFlags()| Paint.UNDERLINE_TEXT_FLAG);

// Set the ActionBar title font size
tv.setTextSize(TypedValue.COMPLEX_UNIT_DIP,24);

// Display a shadow around ActionBar title text
//tv.setShadowLayer(
// 1.f, // radius
// 2.0f, // dx
// 2.0f, // dy
// Color.parseColor("#FF8C00") // shadow color
//);

// Set the ActionBar display option
ab.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);

// Finally, set the newly created TextView as ActionBar custom view
ab.setCustomView(tv);
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
case 0:
// Whatever you want to happen when the first item gets selected
break;
case 1:
// Whatever you want to happen when the second item gets selected
break;
case 2:
// Whatever you want to happen when the thrid item gets selected
break;

}
}

@Override
public void onNothingSelected(AdapterView<?> parent) {

}
}



ERROR: FATAL EXCEPTION: main
java.lang.ClassCastException:
com.example.khas.memorizingwords.ProfileFragment cannot be cast to
com.example.khas.memorizingwords.StartingTestFragment
at com.example.khas.memorizingwords.CombineFragmentActivity$1.onPageSelected(CombineFragmentActivity.java:46)
at android.support.v4.view.ViewPager.dispatchOnPageSelected(ViewPager.java:1862)
at android.support.v4.view.ViewPager.scrollToItem(ViewPager.java:625)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:609)
at android.support.v4.view.ViewPager.onTouchEvent(ViewPager.java:2176)
at android.view.View.dispatchTouchEvent(View.java:7127)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2170)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1905)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2176)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1919)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1925)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1379)
at android.app.Activity.dispatchTouchEvent(Activity.java:2396)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:60)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1873)
at android.view.View.dispatchPointerEvent(View.java:7307)
at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3172)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3117)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4153)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4132)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4224)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:171)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:125)
at android.os.Looper.loop(Looper.java:124)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)

Answer

Your fragment variable is not initialized and you are caling get on it. Also this is not the correct way. Try below code

@Override
                public void onPageSelected(int position) {
                    if(position == 0) {
                        ProfileFragment fragment = (ProfileFragment) getSupportFragmentManager().getFragments().get(1)
                        fragment.setActionBarTitle("Profil");
                    } else {
                        StartingTestFragment fragment2 = (StartingTestFragment) getSupportFragmentManager().getFragments().get(0);
                        fragment2.setActionBarTitle("Anasayfa");
                    }

                }

This is a better version and more general

@Override
        public void onPageSelected(int position) {
            Fragment fragment1 = getActivity().getSupportFragmentManager().getFragments().get(position);
                if(fragment1 instanceof ProfileFragment) {
                    ProfileFragment fragment = (ProfileFragment) fragment1;
                    fragment.setActionBarTitle("Profil" );
                }
                else{
                    StartingTestFragment fragment = (StartingTestFragment) fragment1;
                    fragment.setActionBarTitle("Anasayfa");
                }
            } 

        }

This is the way to change title

setActionBarTitle(YOUR_TITLE);

use this instead of fragment.setACtionBarTitle

I think it is not guaranteed what the order of fragments is when retreived from manager. So simply do this

@Override
            public void onPageSelected(int position) {
                Fragment fragment1 = fragments.get(position);
                if(fragment1 instanceof ProfileFragment) {
                    ProfileFragment fragment = (ProfileFragment) fragment1;
                    fragment.setActionBarTitle("Profil" );
                }
                else{
                    StartingTestFragment fragment = (StartingTestFragment) fragment1;
                    fragment.setActionBarTitle("Anasayfa");
                }

            }

Note: Make your fragments list final by doing this

final List<Fragment> fragments = new ArrayList<>();
Comments