android activity finish 崩溃,Android finish() Activity Not working

I got this error in my codes when i use finish(); "The method finish() is undefined for the type SaveImageTask" . Am I missing some declarations or anything. Can someone please guide me on this.

public class SaveImageTask extends AsyncTask {

private Context context;

private ProgressDialog pDialog;

boolean bCancelled=false;

public SaveImageTask(Context context) {

this.context = context;

}

@Override

protected void onPreExecute() {

// TODO Auto-generated method stub

super.onPreExecute();

pDialog = new ProgressDialog(context);

pDialog.setIndeterminate(false);

pDialog.setCancelable(true);

pDialog.setOnCancelListener(cancelListener);

pDialog.show();

}

@Override

protected String doInBackground(String... args) {

// TODO Auto-generated method stub

// MY STUFF

return null;

}

@Override

protected void onPostExecute(String args) {

// TODO Auto-generated method stub

pDialog.dismiss();

}

OnCancelListener cancelListener=new OnCancelListener(){

@Override

public void onCancel(DialogInterface arg0){

bCancelled=true;

SaveImageTask.this.finish(); // <

}

};

}