I have downloaded the demo screen slider from android (http://ift.tt/1AtG7DO). I've tried to put this in my own project but i get this error:
java.lang.RuntimeException: Unable to start activity ComponentInfo{http://ift.tt/1N74MTn}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2331)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.access$900(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1277)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5479)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.pws.test.demo.D_D_RondleidingMenu.SetupUitgebreideRondleidingButton(D_D_RondleidingMenu.java:24)
at com.pws.test.demo.D_D_RondleidingMenu.onCreate(D_D_RondleidingMenu.java:17)
at android.app.Activity.performCreate(Activity.java:5451)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.access$900(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1277)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5479)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
This is my code:
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
/**
* Demonstrates a "screen-slide" animation using a {@link ViewPager}. Because {@link ViewPager}
* automatically plays such an animation when calling {@link ViewPager#setCurrentItem(int)}, there
* isn't any animation-specific code in this sample.
*
* <p>This sample shows a "next" button that advances the user to the next step in a wizard,
* animating the current screen out (to the left) and the next screen in (from the right). The
* reverse animation is played when the user presses the "previous" button.</p>
*
* @see
*/
public class E_D_Uitgebreid extends FragmentActivity {
/**
* The number of pages (wizard steps) to show in this demo.
*/
private static final int NUM_PAGES = 3;
/**
* The pager widget, which handles animation and allows swiping horizontally to access previous
* and next wizard steps.
*/
private ViewPager mPager;
/**
* The pager adapter, which provides the pages to the view pager widget.
*/
private PagerAdapter mPagerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_e__d__uitgebreid__fragment);
// Instantiate a ViewPager and a PagerAdapter.
mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// When changing pages, reset the action bar actions since they are dependent
// on which page is currently active. An alternative approach is to have each
// fragment expose actions itself (rather than the activity exposing actions),
// but for simplicity, the activity provides the actions in this sample.
invalidateOptionsMenu();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.menu_e__d__uitgebreid, menu);
menu.findItem(R.id.action_previous).setEnabled(mPager.getCurrentItem() > 0);
// Add either a "next" or "finish" button to the action bar, depending on which page
// is currently selected.
MenuItem item = menu.add(Menu.NONE, R.id.action_next, Menu.NONE,
(mPager.getCurrentItem() == mPagerAdapter.getCount() - 1)
? R.string.action_finish
: R.string.action_next);
item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM | MenuItem.SHOW_AS_ACTION_WITH_TEXT);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// Navigate "up" the demo structure to the launchpad activity.
// See http://ift.tt/HxQCh0 for more.
NavUtils.navigateUpTo(this, new Intent(this, D_D_RondleidingMenu.class));
return true;
case R.id.action_previous:
// Go to the previous step in the wizard. If there is no previous step,
// setCurrentItem will do nothing.
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
return true;
case R.id.action_next:
// Advance to the next step in the wizard. If there is no next step, setCurrentItem
// will do nothing.
mPager.setCurrentItem(mPager.getCurrentItem() + 1);
return true;
}
return super.onOptionsItemSelected(item);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
return E_D_Uitgebreid_Fragment.create(position);
}
@Override
public int getCount() {
return NUM_PAGES;
}
}
}
And the fragment:
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
/**
* A fragment representing a single step in a wizard. The fragment shows a dummy title indicating
* the page number, along with some dummy text.
*
* <p>This class is used by the and {@link
* } samples.</p>
*/
public class E_D_Uitgebreid_Fragment extends Fragment {
/**
* The argument key for the page number this fragment represents.
*/
public static final String ARG_PAGE = "page";
/**
* The fragment's page number, which is set to the argument value for {@link #ARG_PAGE}.
*/
private int mPageNumber;
/**
* Factory method for this fragment class. Constructs a new fragment for the given page number.
*/
public static E_D_Uitgebreid_Fragment create(int pageNumber) {
E_D_Uitgebreid_Fragment fragment = new E_D_Uitgebreid_Fragment();
Bundle args = new Bundle();
args.putInt(ARG_PAGE, pageNumber);
fragment.setArguments(args);
return fragment;
}
public E_D_Uitgebreid_Fragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPageNumber = getArguments().getInt(ARG_PAGE);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout containing a title and body text.
ViewGroup rootView = (ViewGroup) inflater
.inflate(R.layout.activity_e__d__uitgebreid__fragment, container, false);
// Set the title view to show the page number.
((TextView) rootView.findViewById(android.R.id.text1)).setText(
Articles.paginatitel[mPageNumber]);
((TextView) rootView.findViewById(android.R.id.text2)).setText(
Articles.paginainhoud[mPageNumber]);
((ImageView) rootView.findViewById(android.R.id.background)).setImageResource(Articles.afbeelding[mPageNumber]);
return rootView;
}
/**
* Returns the page number represented by this fragment object.
*/
public int getPageNumber() {
return mPageNumber;
}
}
I've already changed this, but this didn't work:
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(android.support.v4.app.FragmentManager fm) {
super(fm);
}
and this:
@Override
public android.support.v4.app.Fragment getItem(int position) {
return E_D_Uitgebreid_Fragment.create(position);
}
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