我正在尝试用不同的标题更改我的2片段动作栏。但是，我得到变量'fragment'可能没有在这些行中初始化错误：
ProfileFragment fragment =（ProfileFragment）fragment.get（0）;
StartingTestFragment fragment2 =（StartingTestFragment）fragment2.get（0）;
在onPageSelected方法的CombineFragmentActivity中。感谢帮助。
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) {
}
}