Changement de page sur le bouton cliquez sur ViewPager Android

MISES à jour: Logcat has been added to the question
Je veux changer de vue ( d'un fragment à l'autre. ) sur button Click j'ai essayé beaucoup de choses mais je suis incapable de le faire. J'ai également écrit un CustomViewPager d'arrêter de changer de pages sur le balayage de l'écran. il fonctionne très bien.

Voici mon code:

MyFragment

 public CustomViewPager mViewPager;
public Button next;
public static int count=0;
public static final MyFragment newInstance(String message,ArrayList<String> a)
{
MyFragment f = new MyFragment();
Bundle bdl = new Bundle(1);
bdl.putString(EXTRA_MESSAGE, message);
bdl.putStringArrayList(EXTRA_ARRAY, a);
f.setArguments(bdl);
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String message = getArguments().getString(EXTRA_MESSAGE);
View v = inflater.inflate(R.layout.myfragment_layout, container, false);
spinner = (Spinner)v.findViewById(R.id.spinoptions);
answer = (EditText)v.findViewById(R.id.answer);
next = (Button)v.findViewById(R.id.next);
next.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//TODO Auto-generated method stub
mViewPager.setCurrentItem(1, true);//getItem(-1) for previous  
//it is not working
}
});
ArrayList<String> list = new ArrayList<String>();
list.add("list 1");
list.add("list 2");
list.add("list 3");
Builtprofile.q.get(0).getOptions();
answer.setVisibility(View.INVISIBLE);
spinner.setVisibility(View.VISIBLE);
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(Builtprofile.context,
android.R.layout.simple_spinner_item,getArguments().getStringArrayList(EXTRA_ARRAY));
dataAdapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line); 
spinner.setAdapter(dataAdapter);
TextView messageTextView = (TextView)v.findViewById(R.id.textView);
messageTextView.setText(message);
return v;
}
private int getItem() {
return mViewPager.getCurrentItem();
}

Code pour mon PageAdapter

class MyPageAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
@Override 
public Fragment getItem(int position) {
return this.fragments.get(position);
}
@Override
public int getCount() {
return this.fragments.size();
}
}

Code pour ActivityClass

  public List<Fragment> getFragments(){
List<Fragment> fList = new ArrayList<Fragment>();
for(i=0;i<q.size();i++)
{
fList.add(MyFragment.newInstance(q.get(i).getText(),q.get(i).getOptions()));
}
return fList;
}
public void fragmentopener()
{
List<Fragment> fragments = getFragments();
pageAdapter = new MyPageAdapter(getSupportFragmentManager(), fragments);
ViewPager pager = (ViewPager)findViewById(R.id.viewpager);
pager.setAdapter(pageAdapter);
}

Code pour myCustomViewPager

public class CustomViewPager extends ViewPager {
private boolean isPagingEnabled;
public CustomViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
this.isPagingEnabled = false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (this.isPagingEnabled) {
return super.onTouchEvent(event);
}
return false;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
if (this.isPagingEnabled) {
return super.onInterceptTouchEvent(event);
}
return false;
}
public void setPagingEnabled(boolean b) {
this.isPagingEnabled = b;
}
}

LogCat:

04-07 15:55:53.254: E/AndroidRuntime(17379): FATAL EXCEPTION: main
04-07 15:55:53.254: E/AndroidRuntime(17379): java.lang.NullPointerException
04-07 15:55:53.254: E/AndroidRuntime(17379):    at adapters.MyFragment$1.onClick(MyFragment.java:71)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.view.View.performClick(View.java:3574)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.view.View$PerformClick.run(View.java:14293)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.os.Handler.handleCallback(Handler.java:605)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.os.Handler.dispatchMessage(Handler.java:92)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.os.Looper.loop(Looper.java:137)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at android.app.ActivityThread.main(ActivityThread.java:4448)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at java.lang.reflect.Method.invokeNative(Native Method)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at java.lang.reflect.Method.invoke(Method.java:511)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
04-07 15:55:53.254: E/AndroidRuntime(17379):    at dalvik.system.NativeStart.main(Native Method)

OriginalL'auteur Hassaan Rabbani | 2014-04-07