object reference null exception - exception

I'm trying to access the value of resulterr in button clickevent in order to display it in the messagebox. I'm not getting the value inside the button click event despite setting resulterr list as public. I'm getting exception as object reference not set to an instance of an object. Please rectify the error.
public List<ErrorMsgTemplate> resulterr;
public PPFCWCFServiceClient ppfcObj = new PPFCWCFServiceClient();
public Admin()
: base("Administration")
{
SplashScreenManager.ShowDefaultWaitForm();
InitializeComponent();
GetSource();
ErrorMsg();
FillDivision();
cmbDivision.SelectedIndex = -1;
SplashScreenManager.CloseDefaultWaitForm();
}
public void ErrorMsg()
{
List<ErrorMsgTemplate> resulterr = ppfcObj.getErrorMsgTemplate("ADMIN");
}
private void btnSave_Click(object sender, EventArgs e)
{
try
{
if (cmbDivision.SelectedIndex == -1) //naray added
{
MessageBox.Show(resulterr[0].ERROR_MESSAGE_TEMPLATE.ToString() + "," + resulterr[0].SCREEN_NM.ToString(), "PPFC");
}

I found the issue. I've declared global variable as
public List<ErrorMsgTemplate> resulterr;
and reinstantiated again in ErrorMsg():
public void ErrorMsg()
{
List<ErrorMsgTemplate> resulterr = ppfcObj.getErrorMsgTemplate("ADMIN");
}
Instead, used:
public void ErrorMsg()
{
resulterr = ppfcObj.getErrorMsgTemplate("ADMIN");
}
Now I'm able to access resulterr in btnsave event.

That error comes when your variable value get blank or a space .you can track by null or space to prevent this error

Related

For unknown reason, a button click closes my window. How can I fix this?

I am trying to replicate a simple addition of 2 entries with a button in Monodevelop (shown how to make it step-by-step) but somehow the window closes 2 seconds after pressing the button without actually changing anything.
The code for the button:
using Gtk;
using Frontend.ChatService;
public partial class MainWindow : Gtk.Window
{
public MainWindow() : base(Gtk.WindowType.Toplevel)
{
Build();
}
protected void OnDeleteEvent(object sender, DeleteEventArgs a)
{
Application.Quit();
a.RetVal = true;
}
protected void OnButton1Clicked(object sender, EventArgs e)
{
ChatService client = new ChatService();
int x = Int32.Parse(entry1.Text);
int y = Int32.Parse(entry2.Text);
int sum = client.Add(x, y);
entry1.Text = sum.ToString();
}
}
And the sum (which I tested and think works):
using System;
using System.Web;
using System.Web.Services;
namespace Backend
{
public class ChatService : System.Web.Services.WebService
{
[WebMethod]
public int Add(int x, int y)
{
return x + y;
}
}
}
I left the main file program.cs as generated and is:
using System;
using Gtk;
namespace Frontend
{
class MainClass
{
public static void Main(string[] args)
{
Application.Init();
MainWindow win = new MainWindow();
win.Show();
Application.Run();
}
}
}
The window does pop up as it should and shows no problem until the button is pressed.
Edit:
I forgot to run the backend / server part, which is why the function was not found... (beginners mistake I guess)
Works now
The problem is probably that your code throws an exception you are not aware of. The problem is in the code that handles the button being clicked.
protected void OnButton1Clicked(object sender, EventArgs e)
{
ChatService client = new ChatService();
int x = Int32.Parse(entry1.Text);
int y = Int32.Parse(entry2.Text);
int sum = client.Add(x, y);
entry1.Text = sum.ToString();
}
Let's go line by line:
ChatService client = new ChatService();
Here you are creating a new instance of what it seems to be a system service or maybe a web services. This could throw if the service is not known (in the former case), or if the connection is interrupted or does not reach a destination, etc., in the latter case.
These lines are also delicate:
int x = Int32.Parse(entry1.Text);
int y = Int32.Parse(entry2.Text);
They will throw in case the field entry1 or entry2 are empty, or contain a letter...
In order to manage these cases you need to add try... catch blocks in the appropriate places. Alternately, you can use Int32.TryParse.
For example, assuming the service is in the web:
protected void OnButton1Clicked(object sender, EventArgs e)
{
ChatService client;
int x;
int y;
try {
client = new ChatService();
} catch(HttpRequestException exc) {
client = null;
var dlg = new Gtk.MessageDialog(
this,
Gtk.DialogFlags.Modal,
Gtk.MessageType.Error,
Gtk.ButtonsType.Ok,
"Connection error"
);
dlg.Text = exc.Message;
dlg.Run();
dlg.Destroy();
}
if ( client != null ) {
if ( !int.TryParse( entry1.Text, out x) {
entry1.Text = "0";
x = 0;
}
if ( !int.TryParse( entry2.Text, out y) {
entry2.Text = "0";
y = 0;
}
int sum = client.Add(x, y);
entry1.Text = sum.ToString();
}
}
Getting code which correctly handles errors is always harder, of course.
Hope this helps.

Added items from a places/photo api fetch to a recyclerview and the view is empty

I have been working on an app that requires me to get information such as a Place Name and a PLace Photo from google PLaces Api and set it into a RecyclerView. I am stuck because I managed to get the code to work with no errors but the RecyclerView is empty. What is wrong with my code?
I am stuck because I don't know where the problem is. When I run the code, all the fetchs work and the tags show up in the Log so I am completely lost. My first thought is that I am displaying the code wrong but then I have no recourse to step forward and change it to something else because I am not sure if it would be better or worse.
This is the Fragment for the RecyclerView Item:
public class VenueList extends Fragment{
ArrayList<VenueItem> vIL = new ArrayList<>();
private PlacesClient placesClient;
private Context contextForPlaces;
place ids for the places I am currently using
String[] clubs = {"ChIJO_uSYKNZwokRAC7RLeB0oZ8", "ChIJAQBEylJYwokRLbnrAchQImk",
"ChIJU_26rfpYwokRTNf2K1-7p8E", "ChIJ38hxfnhZwokRx1HSFLj790w", "ChIJBwnlGrdZwokRpf61pMm860c"
, "ChIJpSIzqrhZwokR1KnVMoVty_g", "ChIJMRV7375ZwokRAfltF6Y-wYw", "ChIJYabdHPhYwokRPmAV8GtM3gs",
"ChIJi2dSjQRZwokRuXUKcv4riVc", "ChIJKaKVI79ZwokRN8WicODOIAw", "ChIJwXI8Fb5ZwokRr4JjG4HxSP8",
"ChIJ6bU_E4ZZwokR2ZDbY_IhhrI"};
#Override
public void onAttach(Context context) {
super.onAttach(context);
contextForPlaces = context;
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.menu_venue, container, false);
RecyclerView vRV = view.findViewById(R.id.view_venue);
List<Place.Field> placeFields = Arrays.asList(Place.Field.NAME, Place.Field.PHOTO_METADATAS);
if (!Places.isInitialized()) {
Places.initialize(contextForPlaces, "AIzaSyCKGd3fqmtsDklRGMhnkuIy1GS-j6gRBh8");}
placesClient = Places.createClient(contextForPlaces);
vRV.setHasFixedSize(true);
RecyclerView.LayoutManager vLM = new LinearLayoutManager(this.getActivity());
RecyclerView.Adapter vAdapter = new VenueAdapter(vIL);
// run through each photo to make sure it has a place attached to it then insert each photo and place into the vIL
//createBitmap for fetchPhoto
for (String club : clubs) {
FetchPlaceRequest request = FetchPlaceRequest.newInstance(club, placeFields);
placesClient.fetchPlace(request).addOnSuccessListener((response) -> {
Place place = response.getPlace();
PhotoMetadata photoMetadata = place.getPhotoMetadatas().get(0);
String attributions = photoMetadata.getAttributions();
FetchPhotoRequest photoRequest = FetchPhotoRequest.builder(photoMetadata).setMaxHeight(200).build();
placesClient.fetchPhoto(photoRequest).addOnSuccessListener((fetchPhotoResponse) -> {
Bitmap bitmap = fetchPhotoResponse.getBitmap();
vIL.add(new VenueItem(/*Photo*/bitmap, place/*Name*/));
Log.i(TAG, "Photo Should Be Up: ");
}).addOnFailureListener((exception) -> {
if (exception instanceof ApiException) {
ApiException apiException = (ApiException) exception;
int statusCode = apiException.getStatusCode();
// Handle error with given status code.
Log.e(TAG, "Place not found: " + exception.getMessage());
}
});
Log.i(TAG, "Place found: " + place.getName());
}).addOnFailureListener((exception) -> {
if (exception instanceof ApiException) {
ApiException apiException = (ApiException) exception;
int statusCode = apiException.getStatusCode();
// Handle error with given status code.
Log.e(TAG, "Place not found: " + exception.getMessage());
}
});
}
vRV.setLayoutManager(vLM);
vRV.setAdapter(vAdapter);
return view;
}
This is the part of the RecyclerView Adapter I changed. I used to be a getResourse for the image because the image was from the drawable folder
public void onBindViewHolder(#NonNull VenueViewHolder venueViewHolder, int i) {
VenueItem currentItem = vIAL.get(i);
if(currentItem.getVenueImageResource() == null){
venueViewHolder.vIV.setImageResource(R.drawable.ic_android);
}else
venueViewHolder.vIV.setImageBitmap(currentItem.getVenueImageResource());
venueViewHolder.vTV.setText((CharSequence) currentItem.getVenueDescription());
}
The Item itself which I also had to change a bit from its original. I made the string a Place and the int a Bitmap. I thought that would work.
public class VenueItem {
private Bitmap venueImageResource;
private Place venueDescription;
public VenueItem(Bitmap vIR, Place description) {
venueImageResource = vIR;
venueDescription = description;
}
public Bitmap getVenueImageResource() {
return venueImageResource;
}
public Place getVenueDescription() {
return venueDescription;
}
}
I want to be able to request a place name and a photo of the place using the placesClient and precent it in the for of a RecyclerView. I know the place Ids are correct because the Log returns the names of all the places. But they do not show up on the RecyclerView
I figured out the answer myself.
vRV.setLayoutManager(vLM);
vRV.setAdapter(vAdapter);
I just had to put these two lines into the for loop under the list item so that each item could escape before meing erased

Azure WebJob- QueueTrigger Staging and Production

I have an Azure WebJob that will be used for Staging and Production. The keys for the proper environments are set in the app.config file.
A ConfigManager class reads the properties from the app.config file.
public static string FirstQueue
{
get { return ConfigurationManager.AppSettings["FirstQueue"]; }
}
I would like the QueueTrigger to read the from the proper queue specified in the app.config file.
public static void ProcessFirstQueue([QueueTrigger(ConfigManager.FirstQueue)] string message)
{
//some function
}
However, the QueueTrigger doesn't seem to like this. I get "An attribute argument must be a constant expression, type of expression...." Any suggestions to set this up. I do not want to hard code values in the queue trigger.
Thanks
You can resolve the queue name at runtime using the
INameResolver
Here's an example to demonstrate this:
WebJob Code:
public class Program
{
private static void Main(string[] args)
{
var config =
new JobHostConfiguration("insert connection string")
{
NameResolver = new QueueNameResolver()
};
var host = new JobHost(config);
host.RunAndBlock();
}
public static void ProcessNotification([QueueTrigger("%queueKey%")] string item)
{
//Handle message
}
public static void ProcessPoison([QueueTrigger("%queueKeyPoison%")] string item)
{
//Handle poison message
}
}
Here's the QueueNameResolver class:
public class QueueNameResolver : INameResolver
{
//name = queueKey or queueKeyPoison
public string Resolve(string name)
{
//Use the name to get it from the app.config or somewhere else.
}
}
Hope this helps,

MvxSpinner in Mvvmcross

I have three MvxSpinners in my android view.
These spinners are binded to three different lists.
and Mode of data binding is TwoWay for these spinners.i.e. when this view is
displayed,all of these three spinners are get displayed with the predefined values.
When user change the value in first spinner,then second spinner will be clear and
get loaded with new values based on the selected value in first spinner.
How can I achieve this?
There's many ways to accomplish this, where the code placement is really up to you. Overall the idea would be to have a "SelectedItem" object that you can pass into your method and "Load" the next List.
Please keep in mind that this code is more traditional MVVM, but can easily be converted to MVVMCross equivalent. I believe all these types should be supported by MVVMCross.
private MyFirstObject _selectedFirstObject;
public MyFirstObject SelectedFirstObject
{
get { return _selectedFirstObject; }
set
{
_selectedFirstObject = value;
RaisePropertyChanged("SelectedFirstObject");
if(value != null)
LoadMySecondObjects(value);
}
}
private ObservableCollection<MyFirstObject> _myFirstObjects;
public ObservableCollection<MyFirstObject> MyFirstObjects
{
get { return _myFirstObjects; }
set
{
_myFirstObjects = value;
RaisePropertyChanged("MyFirstObjects");
}
}
private ObservableCollection<MySecondObject> _mySecondObjects;
public ObservableCollection<MySecondObject> MySecondObjects
{
get { return _mySecondObjects; }
set
{
_mySecondObjects = value;
RaisePropertyChanged("MySecondObjects");
}
}
public void LoadMySecondObjects(MyFirstObject current)
{
//Wherever you're pulling data from
MySecondObjects = MyDataService.GetAll(current);
}
protected void RaisePropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public event PropertyChangedEventHandler PropertyChanged;
I had the same problem but only if you add null value (as a default value) to your ItemsSource and try to reset SelectedItem to null. SelectedItem is changed in ViewModel but not in the spinner. In that case there's number of solutions but I used message to inform View to set selected item
public class SpinnerSelectionChanged : MvxMessage
{
public SpinnerSelectionChanged(object sender, string spinnerName, int position): base(sender)
{
SpinnerName = spinnerName;
Position = position;
}
public string SpinnerName { get; set; }
public int Position { get; set; }
}
in View
private void OnSpinnerSelectionChanged(SpinnerSelectionChanged obj)
{
switch (obj.SpinnerName)
{
case "City":
_spinnerCity.SetSelection(obj.Position);
break;
case "Office":
_spinnerOffice.SetSelection(obj.Position);
break;
}
}

How to call method using constructor

I am trying to retrieve data from database and display it using label in java swing. Here are my codes :
public void SetUpJTable() {
// Set Up Database Source
db.setUp("IT Innovation Project");
String sql = "Select topic_title,topic_description,topic_by from forumTopics WHERE topic_id = "
+ topicId + "";
ResultSet resultSet = null;
// Call readRequest to get the result
resultSet = db.readRequest(sql);
try {
while (resultSet.next()) {
jLabel_topicTitle.setText(resultSet.getString("topic_title"));
jLabel_content.setText(resultSet.getString("topic_description"));
jLabel_topicBy.setText(resultSet.getString("topic_by"));
}
resultSet.close();
} catch (Exception e) {
System.out.println(e);
}
}
And I used a constructor to call the method :
public eForumThreadContent(){
SetUpJTable();
};
However, when I run the app, the label is not showing anything. So how can I fix this? I have no idea how to call a method in a class which is without main method. Any guides? Thanks in advance.
To call method from other class:
public class Class1
{
public static void methodFromClass1()
{
// body...
}
}
public class Class2
{
Class1.methodFromClass1(); // thats the way you do it.
}
Ass you can see Class2 has no main class.. You can also call methodFromClass1() in Class1 the same way. But it's all in the manuals..