I am using intellij for the java coursework which is related to clients and databases.
I am receiving the following error
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null
at java.desktop/javax.swing.ImageIcon.<init>(ImageIcon.java:232)
at client.Interface.$$$setupUI$$$(Interface.java)
at client.Interface.<init>(Interface.java:54)
at client.Application.main(Application.java:317)This is the code:
`
` package client;
//region LIBRARIES USED
//Java Libraries:
import javax.print.attribute.HashPrintRequestAttributeSet;
import javax.print.attribute.PrintRequestAttributeSet;
import javax.print.attribute.standard.OrientationRequested;
import javax.swing.*;
import java.awt.print.PrinterException;
import java.io.*;
import java.net.Socket;
import java.text.MessageFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
//Our Classes:
import data.*;
//endregion
public class Application {
//region APPLICATION VARIABLES
private Socket socket;
private ObjectOutputStream packetOutputStream;
private ObjectInputStream packetInputStream;
private Interface guiWindow;
private List<Airport> launchData;
private Airport openAirport;
private List<Route> routeData;
private boolean editMode = false;
//endregion
// Empty Application Constructor:
private Application() {}
//region CONNECT TO SERVER
/**
* Establishes a Connection to the Server.
* <p>
* Attempts to Connect to the Server. Currently
* that is set to 127.0.0.1:2000 a.k.a. the local
* system.
*
* @return Whether a Connection was Established or not.
*/
private boolean connectServer() {
disconnectServer();
guiWindow.printLog(MessageType.STATUS,"Connecting to Server..");
// Connection Succeeded:
try {
socket = new Socket("127.0.0.1", 2000);
packetOutputStream = new ObjectOutputStream(socket.getOutputStream());
packetInputStream = new ObjectInputStream(socket.getInputStream());
guiWindow.printLog(MessageType.STATUS,"Server Connected");
return true;
// Connection Failed:
} catch (IOException ex) {
Logger.getLogger(Application.class.getName()).log(Level.SEVERE, null, ex);
guiWindow.printLog(MessageType.ERROR,ex.toString());
return false;
}
}
//endregion
//region DISCONNECT FROM SERVER
/**
* Disconnects from the Server.
* <p>
* Attempts to Disconnect from the Server.
*/
public void disconnectServer() {
if (socket != null) {
guiWindow.printLog(MessageType.STATUS,"Disconnecting from the Server..");
try {
socket.close();
} catch (IOException ex) {
Logger.getLogger(Application.class.getName()).log(Level.SEVERE, null, ex);
} finally {
socket = null;
}
}
}
//endregion
//region TALK TO SERVER
/**
* Send (& Receive) a Packet to (& from) the Server.
* <p>
* Sends a Packet that contains an instruction (and
* data) to the Server and receives a Packet (with
* information) in return.
*
* @param container A Packet object to be sent.
* @return A Packet object received in return.
*/
public Packet talkToServer(Packet container) {
Packet recievedContainer = null;
// Send Data:
guiWindow.printLog(MessageType.STATUS,"Sending to Server..");
try {
packetOutputStream.writeObject(container);
} catch (IOException e) {
Logger.getLogger(Application.class.getName()).log(Level.SEVERE, null, e);
}
// Receive Data:
guiWindow.printLog(MessageType.STATUS,"Waiting for Server..");
try {
recievedContainer = (Packet) packetInputStream.readObject();
guiWindow.printLog(MessageType.STATUS,"Received Response");
} catch (IOException e) {
guiWindow.printLog(MessageType.ERROR,"(IOException) " + e);
Logger.getLogger(Application.class.getName()).log(Level.SEVERE, null, e);
} catch (ClassNotFoundException e) {
guiWindow.printLog(MessageType.ERROR,"(ClassNotFoundException) " + e);
Logger.getLogger(Application.class.getName()).log(Level.SEVERE, null, e);
}
return recievedContainer;
}
//endregion
//region FIND AIRPORT
/**
* Check if an Airport Exists in the Database.
* <p>
* This Method Looks for the Given Airport from
* a List of Airports Pre-Fetched From the Server.
*
* @param category String Specifying the Search Category ("IATA Code"/"ICAO Code"/"Airport Name").
* @param searchTerm Airport Name or other Identifying Piece of Text.
* @return Whether a Match Was Found.
*/
public boolean matchAirport(String category, String searchTerm) {
if (category.equals(SearchCategories.IATA.toString()) && searchTerm.length()!=3) {
guiWindow.printLog(MessageType.FAILURE,"IATA Code Not 3 Characters Long");
return false;
} else if (category.equals(SearchCategories.ICAO.toString()) && searchTerm.length()!=4) {
guiWindow.printLog(MessageType.FAILURE,"ICAO Code Not 4 Characters Long");
return false;
}
for (int airport=0;airport<launchData.size();airport++) {
if ((category.equals(SearchCategories.NAME.toString()) && launchData.get(airport).getName().toLowerCase().equals(searchTerm.toLowerCase())) ||
(category.equals(SearchCategories.IATA.toString()) && new String(launchData.get(airport).getIATA()).equals(searchTerm.toUpperCase())) ||
(category.equals(SearchCategories.ICAO.toString()) && new String(launchData.get(airport).getICAO()).equals(searchTerm.toUpperCase()))) {
guiWindow.printLog(MessageType.SUCCESS,"Found " + launchData.get(airport).getName() + " Airport");
guiWindow.setAirportLabel("Welcome to " + launchData.get(airport).getName() + " Airport, [" +
new String(launchData.get(airport).getIATA()) + "], [" +
new String(launchData.get(airport).getICAO()) + "], Local Time: "+
(LocalDateTime.now().plusHours((long) launchData.get(airport).getUTCoffset()).format(DateTimeFormatter.ofPattern("HH:mm"))));
openAirport = launchData.get(airport);
return true;
}
}
guiWindow.printLog(MessageType.FAILURE,"Finding Search Term");
return false;
}
//endregion
//region REQUEST ROUTES
/**
* Request Routes for the Open Airport from the Server.
* <p>
* This Method Request A List of Routes for the
* Open Airport and Sends it onwards to the
* table in the GUI Window.
*/
public void requestRoutes() {
Packet request = new Packet(Command.FETCH_ROUTES);
request.sendNumber(openAirport.getID());
Packet response = talkToServer(request);
routeData = response.receiveRouteList();
guiWindow.tableDisplayRoutes(routeData);
if (response.receiveRouteList() != null) {
guiWindow.printLog(MessageType.SUCCESS,"Received Routes for "+openAirport.getName());
} else {
guiWindow.printLog(MessageType.FAILURE, "Receiving Routes for "+openAirport.getName());
}
}
//endregion
//region ADD A ROUTE
/**
* Add a New Route.
* <p>
* This Method Request an Available Route
* ID from the Server and Creates a new
* Route Object.
*/
public void addRoute() {
Packet request = new Packet(Command.FETCH_AVAILABLE_ROUTE_ID);
Packet response = talkToServer(request);
int newID = response.receiveNumber();
routeData.add(new Route(String.valueOf(newID)));
int tableRow = guiWindow.tableAddRow();
guiWindow.tableModifyValue(tableRow,0,String.valueOf(newID));
guiWindow.printLog(MessageType.SUCCESS,"Created Route "+newID);
}
//endregion
//region REMOVE A ROUTE
/**
* Delete a Route.
* <p>
* This Method Removes a Route Based on the
* Row Number that it is Stored/Displayed on.
* @param routeRow The Row Number that Contains the Route.
*/
public void removeRoute(int routeRow) {
guiWindow.tableRemoveRow(routeRow);
guiWindow.printLog(MessageType.SUCCESS,"Removed " + routeData.get(routeRow).getAirline().getName()+"'s " +routeData.get(routeRow).getConnectingAirport().getName() + " Route");
routeData.remove(routeRow);
}
//endregion
//region SYNCHRONISE ROUTES
/**
* Send Routes to the Server for Saving.
* <p>
* This Method Requests the Server to
* update it's database to match the
* clients route info.
*/
public void saveChanges() {
Packet dispatch = new Packet(Command.DISPATCH_CHANGES);
dispatch.sendRouteList(routeData);
dispatch.sendNumber(openAirport.getID());
Packet response = talkToServer(dispatch);
if (response.receiveCondition()) {
guiWindow.printLog(MessageType.SUCCESS,"Updated Routes in Server");
} else {
guiWindow.printLog(MessageType.FAILURE,"Updating Routes in Server");
}
}
//endregion
//region SEND ROUTES TO PRINTER
/**
* Send a Table to the Printer.
* <p>
* Given a JTable, this method sends
* the table to a printer.
*
* @param guiTable The Table that Is Sent to the Printer.
*/
public void printRoutes(JTable guiTable) {
PrintRequestAttributeSet set = new HashPrintRequestAttributeSet();
set.add(OrientationRequested.LANDSCAPE);
MessageFormat header = new MessageFormat("ATC Routes for " + openAirport.getName() + " at "+ (LocalDateTime.now().plusHours((long) openAirport.getUTCoffset())));
MessageFormat footer = new MessageFormat("IATA:["+new String(openAirport.getIATA())+"], ICAO:["+new String(openAirport.getICAO())+"]");
try {
guiTable.print(JTable.PrintMode.FIT_WIDTH, header, footer, false, set, false);
guiWindow.printLog(MessageType.SUCCESS,"Printed Open Routes");
} catch (PrinterException e) {
e.printStackTrace();
guiWindow.printLog(MessageType.ERROR,"(Printing) "+e);
}
}
//endregion
//region VARIABLE ACCESS METHODS
/**
* Returns Whether User is in Edit Mode.
*
* @return Whether Edit Mode is Active or Not.
*/
public boolean getEditMode() {return editMode;}
/**
* Modifies the Edit Mode.
*
* @param mode (True/False).
*/
public void setEditMode(boolean mode) {editMode = mode;}
/**
* Returns the Local List of Routes.
*
* @return A List of Route Objects.
*/
public List<Route> getAppData() {return routeData;}
/**
* Modifies the Local List of Routes.
*
* @param tableData A List of Route Objects.
*/
public void setAppData(List<Route> tableData) {routeData = tableData;}
//endregion
//region MAIN
@SuppressWarnings("CStyleArrayDeclaration")
public static void main(String args[]) {
//Create a New Application and GUI for it:
Application clientApplication = new Application();
clientApplication.guiWindow = new Interface(clientApplication);
//Connect to Server and Download Available Airports:
while (!clientApplication.connectServer()) {
clientApplication.guiWindow.printLog(MessageType.FAILURE,"Connection Failed, Retrying in 3...");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
clientApplication.guiWindow.printLog(MessageType.FAILURE,"Connection Failed, Retrying in 2...");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
clientApplication.guiWindow.printLog(MessageType.FAILURE,"Connection Failed, Retrying in 1...");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
clientApplication.launchData = (clientApplication.talkToServer(new Packet(Command.FETCH_ALL_AIRPORTS))).receiveAirportList();
//Display the Available Airports and Enable Search:
clientApplication.guiWindow.tableDisplayAirports(clientApplication.launchData);
clientApplication.guiWindow.printLog(MessageType.SUCCESS,"Connected, Ready to Select an Airport");
clientApplication.guiWindow.enableSearchFeature(clientApplication);
}
//endregion
``