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PODrawing listView on Canvas - setAdapter causes NullPointerException
 

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  1. PODrawing listView on Canvas - setAdapter causes NullPointerException
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    <p>I've been trying to draw ListView on Canvas, and I get a NullPointerException when I try to set adapter to that listView. I checked it, and it seems listView is null after initialization and I have no idea why.</p> <p>Here is the code:</p> <pre><code>public class Testing extends Activity { MySurface ms; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ms = new MySurface(this); setContentView(ms); String[] stuffArray = {"stuff1", "stuff2"}; ListView listView = (ListView) findViewById(R.id.lvListView); // after this listView is null ArrayAdapter&lt;String&gt; listViewAdapter = new ArrayAdapter&lt;String&gt;(this, android.R.layout.simple_list_item_1, stuffArray); //listView.setAdapter(listViewAdapter); // This line crashes program } @Override protected void onResume() { super.onResume(); ms.resume(); } @Override protected void onPause() { super.onPause(); ms.pause(); } public class MySurface extends SurfaceView implements Runnable { SurfaceHolder holder; Thread t = null; volatile boolean isRunning = false; public MySurface(Context context) { super(context); holder = getHolder(); } public void pause(){ isRunning = false; while(true) { try { t.join(); break; } catch (InterruptedException e) { } } } public void resume(){ isRunning = true; t = new Thread(this); t.start(); } public void run() { LayoutInflater li = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); View v = li.inflate(R.layout.testing, null); v.measure(MeasureSpec.getSize(v.getMeasuredWidth()), MeasureSpec.getSize(v.getMeasuredHeight())); v.layout(0, 0, 0, 0); while(isRunning){ if(!holder.getSurface().isValid()) continue; Canvas canvas = holder.lockCanvas(); canvas.translate(50, 50); v.draw(canvas); holder.unlockCanvasAndPost(canvas); } } } } </code></pre> <p>And the contents of testing.xml layout:</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" &gt; &lt;TextView android:id="@+id/tvTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="List of stuff:" /&gt; &lt;ListView android:id="@+id/lvListView" android:layout_width="wrap_content" android:layout_height="wrap_content" /&gt; &lt;/LinearLayout&gt; </code></pre> <p>LogCat window throws:</p> <pre><code>02-17 12:14:56.359: E/AndroidRuntime(9226): FATAL EXCEPTION: main 02-17 12:14:56.359: E/AndroidRuntime(9226): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.testing/com.example.testing.Testing}: java.lang.NullPointerException 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.os.Handler.dispatchMessage(Handler.java:99) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.os.Looper.loop(Looper.java:123) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread.main(ActivityThread.java:3687) 02-17 12:14:56.359: E/AndroidRuntime(9226): at java.lang.reflect.Method.invokeNative(Native Method) 02-17 12:14:56.359: E/AndroidRuntime(9226): at java.lang.reflect.Method.invoke(Method.java:507) 02-17 12:14:56.359: E/AndroidRuntime(9226): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 02-17 12:14:56.359: E/AndroidRuntime(9226): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 02-17 12:14:56.359: E/AndroidRuntime(9226): at dalvik.system.NativeStart.main(Native Method) 02-17 12:14:56.359: E/AndroidRuntime(9226): Caused by: java.lang.NullPointerException 02-17 12:14:56.359: E/AndroidRuntime(9226): at com.example.testing.Testing.onCreate(Testing.java:30) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 02-17 12:14:56.359: E/AndroidRuntime(9226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615) 02-17 12:14:56.359: E/AndroidRuntime(9226): ... 11 more 02-17 12:14:56.369: E/(160): Dumpstate &gt; /data/log/dumpstate_app_error </code></pre>
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    1. USAdamantium
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    1. COis your listViewAdapter null ?
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      1. USlokoko
    2. CONo, it isn't. Only listView is null.
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      1. PODrawing listView on Canvas - setAdapter causes NullPointerException
      1. USAdamantium
    3. COcould you check if your layout file has this listView in it ? and if it does could you try accessing that to get the listView. Something like : (ListView) ms.findViewById(R.id.lvListView);
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      1. USlokoko
 

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