Impossible de démarrer l'activité ComponentInfo: java.lang.NullPointerException

La Exception:

Unable to start activity ComponentInfo{com.scytec.datamobile.vd.gui.android/com.scytec.datamobile.vd.gui.android.SelectedList}: java.lang.NullPointerException..
Je veux juste montrer liste de case à cocher afficher et sur chaque case afficher "checked", tout simplement, mais je ne sais pas pourquoi, cela me donne une exception.

public class SelectedList extends Activity implements IObserver{
private ListView machine_listview;
ArrayAdapter<String> adapter;
ArrayList<String> arrayListofMachines;
ArrayList<String> arrayListofMachineNumbers;
Vector<MDCMachineStatus> 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<String>(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<?> 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<String>();
arrayListofMachineNumbers = new ArrayList<String>();
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);
}
}

OriginalL'auteur Ahmad Arslan | 2012-02-09