CODEWITHSUNDEEP
javaandroidsqliteandroid-asynctaskandroid-sqlite
Waqar Ahmed
Waqar Ahmed

Reputation: 5068

ClassCastException in android database

I have a MainActivity whose onCreate is 

//called when activity first created
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    searchText = (EditText) findViewById(R.id.searchText);
    utils = new Utils(MainActivity.this);
    db=(new SQLLiteDbHelper(MainActivity.this,utils.getInt(Key.Db_version))).getReadableDatabase(); 
    request = new WebRequest(this);
    status = new AsynGetEmployeeStatus();

}

and sqlitehelper onCreate and constructor is 

//constructor 
public SQLLiteDbHelper(Context context,int dbVersion) {
    super(context,DATABASE_NAME, null, dbVersion);
    this.context = context;
    Log.d("tag","db version is "+DATABASE_VERSION);
    crypt = new Cryptography();
    utils = new Utils(context);
}



//called when activity first created
@Override
public void onCreate(final SQLiteDatabase db) {
    String s;

    try {

        //new LoadData().execute(db);   

        new AsynNetworkOperation(context, ServiceUri.AccessMethod.GET, "loading").execute(ServiceUri.SERVICE_URI+"s?d=abc");  //this line throw exception


    } catch (Throwable t) {
        Toast.makeText(context, t.toString(), Toast.LENGTH_LONG).show();
        Log.d("tag",t.toString());
    }
}

my AsynNetworkOperation class is 

public class AsynNetworkOperation extends AsyncTask<String,Void,Void>{

private Context context = null;
private ProgressDialog dialog = null;
private String title = "";
private WebRequest request = null;
private String accessMethod = "";
private HttpResponse response = null;
AsynResponse delegate = null;

public AsynNetworkOperation(Context context, String method, String dialogTitle)
{
    this.context = context;
    accessMethod = method;
    this.title = dialogTitle;
    delegate = (AsynResponse) context;
}

@Override
protected void onPreExecute() {
    // TODO Auto-generated method stub
    super.onPreExecute();
    dialog = new ProgressDialog(context);
    dialog.setMessage(title);
    dialog.setCanceledOnTouchOutside(false);
    dialog.show();
}

@Override
protected Void doInBackground(String... data) {
    // TODO Auto-generated method stub
    request = new WebRequest(context);
    if(accessMethod.equals(ServiceUri.AccessMethod.GET)){
        response = request.makeHttpGetCall(data[0]);
    }
    return null;
}

@Override
protected void onPostExecute(Void result) {
    // TODO Auto-generated method stub
    super.onPostExecute(result);
    dialog.dismiss();
    delegate.responseResult(response);
    dispose();
}

private void dispose()
{
    context = null;
    dialog = null;
    title = "";
    request = null;
    accessMethod = "";
    delegate = null;
}

}

AsynResponse is 

public interface AsynResponse {

/**
 * This will called when AysncTask finished its execution or when onPostExecute called
 * 
 * @param response
 */
public void responseResult(HttpResponse response);

}

My problem is , whenever sqlitehelper try to execute new AsynNetworkOperation in its onCreate , it throw exception

java.lang.ClassCastException: android.app.MainActivity

can anyone help me finding the problem why it is throwing exception.

Thanks

Upvotes: 0

Views: 107

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1501926

Well this looks like it's probably the problem:

delegate = (AsynResponse) context;

You're casting the context variable to AsynResponse, and that context variable comes from here:

new SQLLiteDbHelper(MainActivity.this, ...)

So it isn't an AsynResponse. It's not even clear what AsynResponse is, but MainActivity presumably isn't compatible with it.

You should work out what you really want that value to be, potentially passing it separately to the Context.

Upvotes: 3

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