Intenta invocar el método virtual 'void android.widget.ListView.setAdapter

Estoy tratando de hacer una vista de lista que contiene imágenes y texto dentro de un fragmento que está en un viewpager con pestañas, así que puedo deslizar hacia la izquierda o la derecha para abrir otro fragmento.

Soy relativamente nuevo en Android, así que lo que podría estar haciendo podría estar completamente equivocado. Puedo construir el proyecto perfectamente bien, pero luego cuando el emulador se ejecuta se bloquea (registro se muestra en la parte inferior de la página).

• El último elemento de Listview está cortado
• Después de la rotación, la transacción de fragmentos da IllegalStateException
• El paquete de compatibilidad de Android no incluye Activity.getFragmentManager ()
• MapView (mapas de android api v2) dentro de la distribución de fragmentos no muestra
• Fragmento isInLayout devuelve false

He creado una aplicación independiente y con éxito fue capaz de crear una vista de lista, pero cuando intento combinar en un fragmento como tal, no funciona. Aquí está mi código siguiente

MainActivity.java

import java.util.ArrayList; import java.util.List; import java.util.Locale; import android.app.ListFragment; import android.content.Intent; import android.support.v7.app.ActionBarActivity; import android.support.v7.app.ActionBar; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.support.v4.app.FragmentPagerAdapter; import android.os.Bundle; import android.support.v4.view.ViewPager; import android.view.Gravity; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast; public class MainActivity extends ActionBarActivity implements ActionBar.TabListener { /** * The {@link android.support.v4.view.PagerAdapter} that will provide * fragments for each of the sections. We use a * {@link FragmentPagerAdapter} derivative, which will keep every * loaded fragment in memory. If this becomes too memory intensive, it * may be best to switch to a * {@link android.support.v4.app.FragmentStatePagerAdapter}. */ SectionsPagerAdapter mSectionsPagerAdapter; /** * The {@link ViewPager} that will host the section contents. */ ViewPager mViewPager; private List<Posts> myPosts = new ArrayList<Posts>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Set up the action bar. final ActionBar actionBar = getSupportActionBar(); actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); // Create the adapter that will return a fragment for each of the three // primary sections of the activity. mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); // Set up the ViewPager with the sections adapter. mViewPager = (ViewPager) findViewById(R.id.pager); mViewPager.setAdapter(mSectionsPagerAdapter); // When swiping between different sections, select the corresponding // tab. We can also use ActionBar.Tab#select() to do this if we have // a reference to the Tab. mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() { @Override public void onPageSelected(int position) { actionBar.setSelectedNavigationItem(position); } }); // For each of the sections in the app, add a tab to the action bar. for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) { // Create a tab with text corresponding to the page title defined by // the adapter. Also specify this Activity object, which implements // the TabListener interface, as the callback (listener) for when // this tab is selected. actionBar.addTab( actionBar.newTab() .setText(mSectionsPagerAdapter.getPageTitle(i)) .setTabListener(this)); } Intent intent = new Intent(MainActivity.this, NotMainActivity.class); startActivity(intent); finish(); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } @Override public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { // When the given tab is selected, switch to the corresponding page in // the ViewPager. mViewPager.setCurrentItem(tab.getPosition()); } @Override public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { } @Override public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { } /** * A {@link FragmentPagerAdapter} that returns a fragment corresponding to * one of the sections/tabs/pages. */ public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { // getItem is called to instantiate the fragment for the given page. // Return a PlaceholderFragment (defined as a static inner class below). switch (position){ case 0: return new TheWallFragment(); case 1: return new PeekFragment(); case 2: return new CameraFragment(); default: break; } return PlaceholderFragment.newInstance(position + 1); } @Override public int getCount() { // Show 3 total pages. return 3; } @Override public CharSequence getPageTitle(int position) { Locale l = Locale.getDefault(); switch (position) { case 0: return getString(R.string.title_section1).toUpperCase(l); case 1: return getString(R.string.title_section2).toUpperCase(l); case 2: return getString(R.string.title_section3).toUpperCase(l); } return null; } } /** * A placeholder fragment containing a simple view. */ public static class PlaceholderFragment extends Fragment { /** * The fragment argument representing the section number for this * fragment. */ private static final String ARG_SECTION_NUMBER = "section_number"; /** * Returns a new instance of this fragment for the given section * number. */ public static PlaceholderFragment newInstance(int sectionNumber) { PlaceholderFragment fragment = new PlaceholderFragment(); Bundle args = new Bundle(); args.putInt(ARG_SECTION_NUMBER, sectionNumber); fragment.setArguments(args); return fragment; } public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.wall_layout, container, false); return rootView; } } } 

NotMainActivity.java

 public class NotMainActivity extends FragmentActivity { private List<Posts> myPosts = new ArrayList<Posts>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); populatePostList(); populateListView(); registerClickCallBack(); System.out.print("Main Activity Started"); } private void populatePostList() { myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); myPosts.add(new Posts("Ottawa, Ontario", "787", "Picture of my Dog!", R.drawable.dog)); } private void populateListView() { ArrayAdapter<Posts> adapter = new MyListAdapter(); ListView list = (ListView) findViewById(android.R.id.list); list.setAdapter(adapter); } //Handles clicks on the list items private void registerClickCallBack(){ ListView list = (ListView) findViewById(android.R.id.list); list.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Posts clickedPost = myPosts.get(position); String message = "You clicked" + position +"Location of post is" + clickedPost.getPostlocation(); Toast.makeText(NotMainActivity.this, message, Toast.LENGTH_LONG).show(); } }); } private class MyListAdapter extends ArrayAdapter<Posts> { public MyListAdapter() { super(NotMainActivity.this, R.layout.item_view, myPosts); } @Override public View getView(int position, View convertView, ViewGroup parent) { // Make sure we have a view to work with {may have given null} View itemView = convertView; if (itemView != null) { itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false); } // Find the post to work with. Posts currentPost = myPosts.get(position); //Fill the view ImageView imageView = (ImageView)itemView.findViewById(R.id.item_postImage); imageView.setImageResource(currentPost.getIconID()); //Fill in Title TextView titleText = (TextView) itemView.findViewById(R.id.item_postText); titleText.setText(currentPost.getPosttitle()); //Set Vote Number TextView voteText = (TextView) itemView.findViewById(R.id.item_postVoteText); voteText.setText(currentPost.getPostvote()); return itemView; } } } 

Posts.java

 public class Posts { private String postlocation; private String postvote; private String posttitle; private int iconID; public Posts(String postlocation, String postvote, String posttitle, int iconID) { this.postlocation = postlocation; this.postvote = postvote; this.posttitle = posttitle; this.iconID = iconID; } public String getPostlocation() { return postlocation; } public String getPostvote() { return postvote; } public String getPosttitle() { return posttitle; } public int getIconID() { return iconID; } 

TheWallFragment.java

 public class TheWallFragment extends android.support.v4.app.ListFragment { List<Posts> myPosts = new ArrayList<Posts>(); private String[] strListView; private ListView myListView; private int number; public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.wall_layout, container, false); return rootView; } } 

Activity_main.xml

 <android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/pager" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" /> 

AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.gnumbu.errolgreen.testing" > <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".NotMainActivity"> </activity> </application> </manifest> 

Item_view.xml

  <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/item_postImage" android:src="@drawable/dog" android:maxWidth="80dp" android:minHeight="80dp" android:adjustViewBounds="true" android:layout_marginLeft="14dp" android:layout_marginStart="14dp" android:layout_alignParentTop="true" android:layout_toRightOf="@+id/item_upvoteArrow" android:layout_toEndOf="@+id/item_upvoteArrow" android:layout_alignBottom="@+id/item_downvotearrow" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="This is my dog! My Dog is amazing, give it a lick!" android:id="@+id/item_postText" android:paddingStart="5dp" android:layout_above="@+id/item_downvotearrow" android:layout_toRightOf="@+id/item_postImage" android:layout_toEndOf="@+id/item_postImage" /> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/item_upvoteArrow" android:src="@drawable/upvotearrow" android:maxHeight="24dp" android:maxWidth="24dp" android:adjustViewBounds="true" android:layout_alignParentTop="true" android:layout_alignLeft="@+id/item_downvotearrow" android:layout_alignStart="@+id/item_downvotearrow" android:clickable="true" /> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/item_downvotearrow" android:src="@drawable/downvotearrow" android:maxWidth="24dp" android:maxHeight="24dp" android:adjustViewBounds="true" android:layout_marginLeft="9dp" android:layout_marginStart="9dp" android:layout_below="@+id/item_postVoteText" android:layout_alignParentLeft="true" android:layout_alignParentStart="true" android:longClickable="false" android:clickable="true" /> <TextView android:layout_height="wrap_content" android:text="22" android:id="@+id/item_postVoteText" android:maxHeight="20dp" android:focusableInTouchMode="false" android:visibility="visible" android:singleLine="true" android:gravity="center" android:enabled="true" android:layout_below="@+id/item_upvoteArrow" android:layout_alignLeft="@+id/item_upvoteArrow" android:layout_alignStart="@+id/item_upvoteArrow" android:nestedScrollingEnabled="false" android:layout_width="wrap_content" android:layout_toStartOf="@+id/item_postImage" /> </RelativeLayout> 

Wall_layout.xml

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="New Text" android:id="@+id/textView" android:layout_gravity="center_horizontal" /> <ListView android:id="@android:id/list" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> 

Registro de errores

  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) at android.app.ActivityThread.access$800(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5223) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference at com.gnumbu.errolgreen.testing.NotMainActivity.populateListView(NotMainActivity.java:70) at com.gnumbu.errolgreen.testing.NotMainActivity.onCreate(NotMainActivity.java:43) at android.app.Activity.performCreate(Activity.java:5937) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)            at android.app.ActivityThread.access$800(ActivityThread.java:144)            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)            at android.os.Handler.dispatchMessage(Handler.java:102)            at android.os.Looper.loop(Looper.java:135)            at android.app.ActivityThread.main(ActivityThread.java:5223)            at java.lang.reflect.Method.invoke(Native Method)            at java.lang.reflect.Method.invoke(Method.java:372)            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

Nuevo error

  Process: com.gnumbu.errolgreen.testing, PID: 5304 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference at android.widget.AbsListView.obtainView(AbsListView.java:2360) at android.widget.ListView.measureHeightOfChildren(ListView.java:1270) at android.widget.ListView.onMeasure(ListView.java:1182) at android.view.View.measure(View.java:17430) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) at android.view.View.measure(View.java:17430) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) at android.view.View.measure(View.java:17430) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436) at android.widget.LinearLayout.measureVertical(LinearLayout.java:722) at android.widget.LinearLayout.onMeasure(LinearLayout.java:613) at android.view.View.measure(View.java:17430) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463) at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560) at android.view.View.measure(View.java:17430) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2001) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1166) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1372) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767) at android.view.Choreographer.doCallbacks(Choreographer.java:580) at android.view.Choreographer.doFrame(Choreographer.java:550) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5221) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

 if (itemView != null) { itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false); } 

 if (itemView == null) { itemView = getLayoutInflater().inflate(R.layout.item_view, parent, false); } 

 indexBar = (ProgressBar) findViewById(R.id.mainIndexProgressBar); Drawable d = ContextCompat.getDrawable(getApplicationContext(), R.drawable.ic_check_circle_black_24dp); d.setBounds(0, 0, indexBar.getWidth(), indexBar.getHeight()); indexBar.setIndeterminateDrawable(d); indexBar.setIndeterminate(true); indexBar.requestLayout();