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POUnable to start activity ComponentInfo: java.lang.NullPointerException
 

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    <p>The <code>Exception</code>:</p> <p><code>Unable to start activity ComponentInfo{com.scytec.datamobile.vd.gui.android/com.scytec.datamobile.vd.gui.android.SelectedList}: java.lang.NullPointerException..</code> I just want to show checkbox list view and on every check it display "checked", simply but i don't know why this gives me an exception.</p> <pre><code>public class SelectedList extends Activity implements IObserver{ private ListView machine_listview; ArrayAdapter&lt;String&gt; adapter; ArrayList&lt;String&gt; arrayListofMachines; ArrayList&lt;String&gt; arrayListofMachineNumbers; Vector&lt;MDCMachineStatus&gt; machineStatus_vector; Handler handler; private static int oldPosition = 0; private Boolean firstClick = true; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.machinelistview); machine_listview = (ListView) findViewById(R.id.machine_listview); machine_listview.setFastScrollEnabled(true); MachineStatusSingleton.Register(this); getData(); adapter = new ArrayAdapter&lt;String&gt;(SelectedList.this, R.layout.selectedlist,R.id.text1, arrayListofMachines); machine_listview.setAdapter(adapter); machine_listview.setSelection(oldPosition); CheckBox chk=(CheckBox)findViewById(R.id.check); chk.setOnCheckedChangeListener(new OnCheckedChangeListener() { public void onCheckedChanged(CompoundButton arg0, boolean arg1) { TextView txt=(TextView)findViewById(R.id.xtra); if (arg1) Log.d("", "abul, checked") ; else Log.d("", "abul, not checked") ; } } ); machine_listview.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView&lt;?&gt; arg0, View arg1, int position, long arg3) { // TODO Auto-generated method stub oldPosition = position; MachineStatusSingleton.setMachineNumber(arrayListofMachineNumbers.get(position)); SelectedList.this.finish(); } }); handler = new Handler(){ public void handleMessage(android.os.Message msg) { machine_listview.setAdapter(adapter); adapter.notifyDataSetChanged(); }; }; } public void Update(ISubject arg0) { // TODO Auto-generated method stub } @Override public void onDestroy() { super.onDestroy(); MachineStatusSingleton.Unregister(this); } private void getData(){ machineStatus_vector = MachineStatusSingleton.GetData(); arrayListofMachines = new ArrayList&lt;String&gt;(); arrayListofMachineNumbers = new ArrayList&lt;String&gt;(); for(MDCMachineStatus temp: machineStatus_vector){ arrayListofMachines.add(temp.toString()); arrayListofMachineNumbers.add(temp.getNumber()); } Collections.sort(arrayListofMachines); Collections.sort(arrayListofMachineNumbers); } private void updateData(){ getData(); handler.sendEmptyMessage(0); adapter.notifyDataSetChanged(); int index = machine_listview.getFirstVisiblePosition(); View v = machine_listview.getChildAt(0); int top = (v == null) ? 0 : v.getTop(); // ... // restore machine_listview.setSelectionFromTop(index, top); } } </code></pre>
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    1. USLuksprog
    1. USAhmad Arslan
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    1. COCould you post the full stack trace?
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      1. USSly
    2. COIn your `LogCat`, take a look at the last couple of **red** lines which will give you the precise line number of the precise java file that's the reason for crash. It reads something like `Dalvik... NullPointerException caused by...`
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      1. UStipycalFlow
    3. COsorry guys.. i have a problem in this: CheckBox chk=(CheckBox)findViewById(R.id.check); chk.setOnCheckedChangeListener(new OnCheckedChangeListener() { public void onCheckedChanged(CompoundButton arg0, boolean arg1) { TextView txt=(TextView)findViewById(R.id.xtra); if (arg1) Log.d("", "abul, checked") ; else Log.d("", "abul, not checked") ; } } );
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      1. USAhmad Arslan
 

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