I'm getting the following error:
6-15 19:57:50.291 9743-9743/com.example.utkarsh.beatle.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:392)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
at android.widget.AbsListView.obtainView(AbsListView.java:2214)
at android.widget.ListView.makeAndAddView(ListView.java:1852)
at android.widget.ListView.fillDown(ListView.java:678)
at android.widget.ListView.fillFromTop(ListView.java:739)
at android.widget.ListView.layoutChildren(ListView.java:1668)
at android.widget.AbsListView.onLayout(AbsListView.java:2037)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1021)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1021)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1670)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1528)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1441)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:14099)
at android.view.ViewGroup.layout(ViewGroup.java:4464)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2183)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1947)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4879)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
at android.view.Choreographer.doCallbacks(Choreographer.java:579)
at android.view.Choreographer.doFrame(Choreographer.java:548)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:5299)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
My code
package com.example.utkarsh.beatle.app;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MainActivity extends FragmentActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState==null)
{
getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
}
}
@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);
}
public static class PlaceholderFragment extends Fragment {
private ArrayAdapter<String> mForecastAdapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
String[] forecastArray= {"Today-Sunny-88/63", "Tommorrow-windy-88/94", "wed-aloo-alooo"};
List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.fragment_main, R.id.list_item_forecast_textview, weekForecast);
ListView listView = (ListView) rootView.findViewById(R.id.list_view_forecast);
listView.setAdapter(mForecastAdapter);
return rootView;
}
}
}
These are the .xml that i have used, I don't know about the issues with the layout please help me with it , I am just following the videos on udacity "developing android app" every code is written like what is written by them I don't know what is the fault from my side.
**activity_main.xml**
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.utkarsh.beatle.app.MainActivity"
tools:ignore="MergeRootFrame"
android:id="@+id/container"/>
**fragment_main.xml**
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.utkarsh.beatle.app.MainActivity$PlaceholderFragment">
<ListView
android:id="@+id/list_view_forecast"
android:layout_width="match_parent"
android:layout_height="match_parent" />
**list_item_forecast.xml**
<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?android:attr/listPreferredItemHeight"
android:gravity="center_vertical"
android:id="@+id/list_item_forecast_textview"/>
答案 0 :(得分：0)
You're using a wrong layout for your list items. Change
mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.fragment_main, ...
to
mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, ...
The NPE comes when ArrayAdapter calls findViewById() to get the specified TextView from the list item layout but the view is not there and a null is returned. Calling setText() on this null TextView is the NPE.
答案 1 :(得分：0)
You have to use right layout for list item.
Use this
mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_item_forecast_textview, weekForecast);
Instead Of:
mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.fragment_main, R.id.list_item_forecast_textview, weekForecast);
It will remove your null pointer exception completely!!