Thursday, 10 July 2014

NullPointerException with Fragment and ViewPager



I have some problems with my code. I have a NullPointerException in the code below. I'm trying to create a swipe between 3 differents fragments.


I don't understand where is my mistake so please help me :p


DummyFragment.java :



package com.example.testslide;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class DummyFragment extends Fragment {

public static DummyFragment newInstance(String chaine) {
DummyFragment fragment = new DummyFragment();
Bundle args = new Bundle();
args.putString("KEY_STRING", chaine);
fragment.setArguments(args);
return fragment;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.milieu, container);
TextView textView = (TextView) v.findViewById(R.id.textView1);
Bundle args = getArguments();
textView.setText(args.getString("KEY_STRING"));
return v;
}

}


ViewPagerAdapter



package com.example.testslide;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

public class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}

@Override
public Fragment getItem(int pos) {
switch(pos) {
case 1: return DummyFragment.newInstance("Je suis le premier écran !");
case 2: return DummyFragment.newInstance("Je suis le second écran !");
case 3: return DummyFragment.newInstance("Je suis le troisième écran !");
}
return null;
}

@Override
public int getCount() {
return 3;
}
}


ViewPagerActivity :



package com.example.testslide;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;


public class ViewPagerActivity extends FragmentActivity {
private ViewPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager);
// Set up the adapter.
mSectionsPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());

// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.viewPager);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
}


viewpager.xml :



<android.support.v4.view.ViewPager
xmlns:android="http://ift.tt/nIICcg"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/viewPager">
</android.support.v4.view.ViewPager>


milieu.xml



<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://ift.tt/nIICcg"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >


<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="20dp"
android:text="Page du milieu" />

</LinearLayout>


LogCat :



07-10 08:25:26.211: E/AndroidRuntime(607): FATAL EXCEPTION: main
07-10 08:25:26.211: E/AndroidRuntime(607): java.lang.NullPointerException
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:394)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:389)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:99)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:832)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.view.ViewPager.populate(ViewPager.java:982)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.View.measure(View.java:10828)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4351)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.widget.FrameLayout.onMeasure(FrameLayout.java:267)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.View.measure(View.java:10828)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4351)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1284)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.widget.LinearLayout.measureVertical(LinearLayout.java:613)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.widget.LinearLayout.onMeasure(LinearLayout.java:519)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.View.measure(View.java:10828)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4351)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.widget.FrameLayout.onMeasure(FrameLayout.java:267)
07-10 08:25:26.211: E/AndroidRuntime(607): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:1889)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.View.measure(View.java:10828)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.ViewRoot.performTraversals(ViewRoot.java:938)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.view.ViewRoot.handleMessage(ViewRoot.java:2040)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.os.Handler.dispatchMessage(Handler.java:99)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.os.Looper.loop(Looper.java:132)
07-10 08:25:26.211: E/AndroidRuntime(607): at android.app.ActivityThread.main(ActivityThread.java:4123)
07-10 08:25:26.211: E/AndroidRuntime(607): at java.lang.reflect.Method.invokeNative(Native Method)
07-10 08:25:26.211: E/AndroidRuntime(607): at java.lang.reflect.Method.invoke(Method.java:491)
07-10 08:25:26.211: E/AndroidRuntime(607): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
07-10 08:25:26.211: E/AndroidRuntime(607): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
07-10 08:25:26.211: E/AndroidRuntime(607): at dalvik.system.NativeStart.main(Native Method)

1 comment:

  1. I think you should add break statements after each return in the switch statement

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