AbstractInputFile is an abstract class and has the following code below:
public abstract class AbstractInputFile {
static final public int MIN_BILLING_CYCLE = 1;
static final public int MAX_BILLING_CYCLE = 12;
private File file;
public AbstractInputFile() {
}
public abstract List<Request> readFile() throws IOException, BarsException;
public File getFile() {
return file;
}
public void setFile(File file) {
this.file = file;
}
}
CSVInputFileImpl is a subclass of AbstractInputFile, thus inheriting the readFile() method. What it does is it reads the contents of a csv file using a buffered reader, stores it in an arraylist, and returns it.
public List<Request> readFile() throws IOException, BarsException {
List<Request> requests = new ArrayList<>();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/dd/yyyy");
String line = "";
//READ CSV FILE
try {
BufferedReader br = new BufferedReader(new FileReader(getFile()));
int row = 1;
int index = 0;
while ((line = br.readLine()) != null) {
String[] data = line.split(",", 3);
//Validate if billing cycle ranges 1-12
try {
int billingCycle = Integer.parseInt(data[0]);
if(billingCycle <= MAX_BILLING_CYCLE && billingCycle >= MIN_BILLING_CYCLE) {
request.setBillingCycle(billingCycle);
} else {
log.error(BILLING_CYCLE_NOT_ON_RANGE + row);
throw new BarsException(BILLING_CYCLE_NOT_ON_RANGE + row);
}
} catch (BarsException e) {
log.error(INVALID_BILLING_CYCLE + row);
throw new BarsException(INVALID_BILLING_CYCLE + row);
}
//Validate start date
try {
LocalDate startDate = LocalDate.parse(data[1], formatter);
request.setStartDate(startDate);
} catch (DateTimeParseException e) {
log.error(INVALID_START_DATE_FORMAT + row);
throw new BarsException(INVALID_START_DATE_FORMAT + row);
}
//Validate end date
try {
LocalDate endDate = LocalDate.parse(data[2], formatter);
request.setStartDate(endDate);
} catch (DateTimeParseException e) {
log.error(INVALID_END_DATE_FORMAT + row);
throw new BarsException(INVALID_END_DATE_FORMAT + row);
}
row++;
//Add the requests to array list created previously
requests.add(index,new Request(request.getBillingCycle(), request.getStartDate(), request.getEndDate()));
index++;
}
//Validate if file exists
} catch (FileNotFoundException e) {
throw new BarsException(NO_SUPPORTED_FILE);
} catch (IOException e) {
throw new IOException(PATH_DOES_NOT_EXIST);
}
return requests;
}
In another public class FileProcessor, I am instructed to get the array list using List<Request> requests = abstractInputFile.readFile(); but is unable to do so because I am getting the error Non-static method 'readFile()' cannot be referenced from a static context.
public List<Request> execute(File file) throws BarsException {
InputFileFactory fact = InputFileFactory.getInstance();
try {
fact.getInputFile(file);
} catch (BarsException e) {
throw new BarsException(NO_SUPPORTED_FILE);
}
List<Request> requests = AbstractInputFile.readFile();
return requests;
}
My question is: How will I be able to retrieve the arraylist and return it in the execute(file) method? There might be a lot more errors in other areas of the code and logic but I'd appreciate any help and suggestions.
First things first, AbstractInputFile.readFile() can't be called for 2 reasons: readFile() in the AbstractInputFile class is abstract, and it is an instance method.
From what you wrote here, you implement the readFile() method in the subclass, CSVInputFileImpl. Therefore, in this case, your readFile() calls should be based on THIS class, not AbstractInputFile. However, this is still classified as an instance method, meaning you need to first create an instance of CSVInputFileImpl before you can call readFile(). I would correct the code like this (I'm making assumptions that the CSVInputFileImpl class is structured the same as AbstractInputFile, but make sure the file instance var is set):
CSVInputFileImpl csvInputFileImpl = new CSVInputFileImpl();
csvInputFileImpl.setFile(file);
List<Request> requests = csvInputFileImpl.readFile();
return requests;
Related
Context
I made a Java application, and need to run two instances of that application, synchronizing some of their attributes via socket each time there's some change. To communicate those changes, Serializable objects are sent through a socket using ObjectStreams (input and output) using read/writeUTF() for an identifier, and read/writeObject() and flush(). The app is the exact same .jar, run twice with some changes like having different ports and ip (if necessary).
Problem
I noticed that objects of some of my classes (e.g. Notification) were sent and received without any troubles, but objects from another class (RegisteredUsers) weren't sent (or received) properly. So I ran some tests to send objects between the two apps and found that the object is being sent and isn't null, it's attribute (a HashMap<String,User>) is also being sent and isn't null, but is always empty.
So I decided to scale it down to what the problem was exactly: I'm trying to write an object through a Stream, and read it in a different process of the same .jar, and with most classes it seems to work, but it doesn't with one.
There seems to be something I'm missing or don't understand about this serialization process, if the object is written and read during the execution of the same process it works, but not if this object is read on another instance of the same app. I even added a HashMap to Notification with the same creation process, but it still works, I really don't get it, what am I missing?
Code
I have taken some code from the bigger app and trimmed it down to the basic problem if anyone wants to test it. To reproduce the errors, run Main1, which will create the two files with an object persisted in each one (one with a Notification object and the other with a RegisteredUsers object) and shows their information, then Main2, which reads them from the files and shows their information, and the problem should be printed. That being that reg3's HashMap is empty and thus neither of the Users are registered.
Main1
public class Main1 {
public static void main(String[] args) {
String regFile = "registry.txt";
String notificationFile = "notification.txt";
Persistence pers = new Persistence();
RegisteredUsers reg1 = new RegisteredUsers();
RegisteredUsers reg2 = new RegisteredUsers();
reg1.register("Name1", "127.0.0.1");
reg1.register("Name2", "127.0.0.1");
try {
pers.writeReg(reg1, regFile);
} catch (IOException e) {
System.out.println("Error writing registry.");
}
try {
reg2 = pers.readReg(regFile);
} catch (IOException e) {
System.out.println("Error reading registry.");
}
System.out.println("Original registry: ");
System.out.println(reg1.isRegistered("Name1") + " " + reg1.isRegistered("Name2"));
System.out.println("Registry read from file: ");
System.out.println(reg2.isRegistered("Name1") + " " + reg2.isRegistered("Name2"));
Notification noti1 = new Notification("Name", "127.0.0.1");
Notification noti2 = new Notification(); //not necesary but it's the way it's done in the bigger app.
try {
pers.writeNotif(noti1, notificationFile);
} catch (IOException e) {
System.out.println("Error writing notification.");
}
try {
noti2 = pers.readNotif(notificationFile);
} catch (IOException e) {
System.out.println("Error reading notification.");
}
System.out.println("Original notification: ");
System.out.println(noti1.getAttributes().get(0) + " " + noti1.getAttributes().get(1));
System.out.println(noti1.getMap());
System.out.println("Notification read from file: ");
System.out.println(noti2.getAttributes().get(0) + " " + noti2.getAttributes().get(1));
System.out.println(noti2.getMap());
}
}
Main2
public class Main2 {
public static void main(String[] args) {
String regFile = "registry.txt";
String notificationFile = "notification.txt";
Persistence pers = new Persistence();
RegisteredUsers reg3 = new RegisteredUsers();
try {
reg3 = pers.readReg(regFile);
} catch (IOException e) {
System.out.println("Error reading registry.");
}
if (reg3 == null) {
System.out.println("reg3 is null");
}
if (reg3.getMap() == null)
System.out.println("reg3 has a null map");
if (reg3.getMap().isEmpty())
System.out.println("reg3 has an empty map");
System.out.println("Registry read from file on another process: ");
System.out.println(reg3.isRegistered("Name1") + " " + reg3.isRegistered("Name2"));
Notification noti3 = new Notification(); //not necesary but it's the way it's done in the bigger app.
try {
noti3 = pers.readNotif(notificationFile);
} catch (IOException e) {
System.out.println("Error reading notification.");
}
System.out.println("Notification read from file on another process: ");
System.out.println(noti3.getAttributes().get(0) + " " + noti3.getAttributes().get(1));
System.out.println(noti3.getMap());
}
}
A Class to persist the objects in the files:
public class Persistence {
public void writeReg(RegisteredUsers regus, String file) throws IOException {
try(FileOutputStream fos = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(fos);) {
oos.writeObject(regus);
oos.flush();
}
}
public RegisteredUsers readReg(String file) throws IOException {
RegisteredUsers regus = null;
try(FileInputStream fis = new FileInputStream(file);
ObjectInputStream ois = new ObjectInputStream(fis);) {
regus = (RegisteredUsers) ois.readObject();
} catch (ClassNotFoundException e) {
System.out.println("Wrong class.");
}
return regus;
}
public void writeNotif(Notification regus, String file) throws IOException {
try(FileOutputStream fos = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(fos);) {
oos.writeObject(regus);
oos.flush();
}
}
public Notification readNotif(String file) throws IOException {
Notification notif = null;
try(FileInputStream fis = new FileInputStream(file);
ObjectInputStream ois = new ObjectInputStream(fis);) {
notif = (Notification) ois.readObject();
} catch (ClassNotFoundException e) {
System.out.println("Wrong class.");
}
return notif;
}
}
RegisteredUsers
public class RegisteredUsers implements Serializable {
private static HashMap<String, User> users;
public RegisteredUsers() {
users = new HashMap<String, User>();
}
public HashMap<String, User> getMap() {
return users;
}
public boolean isRegistered(String name) {
User us = users.get(name);
return us != null;
}
public void register(String name, String ip) {
users.put(name, new User(name, ip, false));
}
}
Notification
public class Notification implements Serializable {
private ArrayList<String> attributes;
private HashMap<String, User> map = new HashMap<>();
public Notification() {
}
public Notification(String name, String ip) {
attributes = new ArrayList<String>();
attributes.add(0, name);
attributes.add(1, ip);
map.put(ip, new User(name, ip, false));
}
public ArrayList<String> getAttributes() {
return attributes;
}
public HashMap<String, User> getMap() {
return map;
}
}
User
public class User implements Serializable {
private String name;
private String ip;
private boolean connection_state;
public User(String name, String ip, boolean connection_state) {
this.name = name;
this.ip = ip;
this.connection_state = connection_state;
}
}
In java static fields are implicitly transient, and transient fields are not serialized.
If you modify the RegisterdUsers to
public class RegisteredUsers implements Serializable {
private HashMap<String, User> users; // static modifier is removed
...
}
The serialization will work.
I have a ReadFromFile class implementing Callable and returning a list of strings. This list of Strings should be displayed in the console, but stranger things it is not displayed. In debugger I see that the list is not empty and the data inside is correct. But it is not displayed.
Here is the code:
ReadFromFile
public class ReadFromFile implements Callable<List<String>> {
private File file;
public ReadFromFile(File file) {
this.file = file;
}
#Override
public List<String> call() throws Exception {
String row = null;
List<String> data = new ArrayList<>();
try (BufferedReader csvReader = new BufferedReader(new FileReader(file))) {
while ((row = csvReader.readLine()) != null) {
data = Arrays.asList(row.split(";"));
}
} catch (IOException i) {
System.out.println("Break");
}
return data;
}}
Here is the method, where data from future should be assigned to the list to be displayed:
public static void setupShop(List<String> menuItems, Map<String, Integer> stock, Map<String, Float> price) throws IOException, ExecutionException, InterruptedException {
menuItems = Executors.newFixedThreadPool(1).submit(new ReadFromFile(menuFile)).get();
}
I excluded the code for maps here, it doesn't influence this case.
But! If I create another list and assign the data from Future to it, data is displayed correctly:
public static void setupShop(List<String> menuItems, Map<String, Integer> stock, Map<String, Float> price) throws IOException, ExecutionException, InterruptedException {
List <String> menu = new ArrayList<>();
menu = Executors.newFixedThreadPool(1).submit(new ReadFromFile(menuFile)).get();
for (int i = 0; i<menu.size();i++)
{
menuItems.add(menu.get(i));
}
So, the question is, why can't I print data from future.get directly?
data = Arrays.asList(row.split(";")); this row is wrong, you re-assign the list so the list will take the value of your file's last line.
use data.addAll(Arrays.asList(row.split(";"))); instead. Maybe the problem is here, assuming that your last line is an empty row
UPDATE:
Here a reproductible minimal working example:
public class ReadFromFile implements Callable<List<String>> {
private File file;
public ReadFromFile(File file) {
this.file = file;
}
#Override
public List<String> call() throws Exception {
String row = null;
List<String> data = new ArrayList<>();
try (BufferedReader csvReader = new BufferedReader(new FileReader(file))) {
while ((row = csvReader.readLine()) != null) {
data.addAll(Arrays.asList(row.split(";")));
}
} catch (IOException i) {
System.out.println(i.getMessage());
}
return data;
}
}
Tested with main class
public class Main {
public static void main(String[] args) {
try {
List<String> menu = Executors.newFixedThreadPool(1).submit(new ReadFromFile(new File("src/test.csv"))).get();
menu.forEach(System.out::println);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
CSV file:
sfdfdsf;fdsgfdfsg;gfdgff
gfsgfd;fgfdg;gfgdfg
Output of main execution:
sfdfdsf
fdsgfdfsg
gfdgff
gfsgfd
fgfdg
gfgdfg
I'm a novice when it comes to JSPs and JAVA.
How do I get the output from the below code to display on a jsp, considering that it runs everything from the main and contains non-public methods, a nested static class etc?
I know that we are not supposed to use java code on jsp but my first step in this proof on concept exercise is to get the code running and returning data from a backend then I can set about using EL etc.
I can run the program, with the correct config settings, from within Eclipse and all works fine with the output appearing on the console but I'm really not sure how to access it from within a jsp.
How do I access the static class and static methods from a jsp if they aren't public?
All help greatly appreciated.
public class CustomDestinationDataProvider
{
static class MyDestinationDataProvider implements DestinationDataProvider
{
private DestinationDataEventListener eL;
private HashMap<String, Properties> secureDBStorage = new HashMap<String, Properties>();
public Properties getDestinationProperties(String destinationName)
{
try
{
//read the destination from DB
Properties p = secureDBStorage.get(destinationName);
if(p!=null)
{
//check if all is correct, for example
if(p.isEmpty())
throw new DataProviderException(DataProviderException.Reason.INVALID_CONFIGURATION, "destination configuration is incorrect", null);
return p;
}
return null;
}
catch(RuntimeException re)
{
throw new DataProviderException(DataProviderException.Reason.INTERNAL_ERROR, re);
}
}
public void setDestinationDataEventListener(DestinationDataEventListener eventListener)
{
this.eL = eventListener;
}
public boolean supportsEvents()
{
return true;
}
//implementation that saves the properties in a very secure way
void changeProperties(String destName, Properties properties)
{
synchronized(secureDBStorage)
{
if(properties==null)
{
if(secureDBStorage.remove(destName)!=null)
eL.deleted(destName);
}
else
{
secureDBStorage.put(destName, properties);
eL.updated(destName); // create or updated
}
}
}
} // end of MyDestinationDataProvider
//business logic
void executeCalls(String destName)
{
JCoDestination dest;
try
{
dest = JCoDestinationManager.getDestination(destName);
dest.ping();
System.out.println("Destination " + destName + " works");
step4WorkWithTable(dest);
}
catch(JCoException e)
{
e.printStackTrace();
System.out.println("Execution on destination " + destName+ " failed");
}
}
static Properties getDestinationPropertiesFromUI()
{
//adapt parameters in order to configure a valid destination
Properties connectProperties = new Properties();
// Add code here to set config settings
return connectProperties;
}
public static void main(String[] args)
{
MyDestinationDataProvider myProvider = new MyDestinationDataProvider();
//register the provider with the JCo environment;
//catch IllegalStateException if an instance is already registered
try
{
com.sap.conn.jco.ext.Environment.registerDestinationDataProvider(myProvider);
}
catch(IllegalStateException providerAlreadyRegisteredException)
{
//somebody else registered its implementation,
//stop the execution
throw new Error(providerAlreadyRegisteredException);
}
String destName = "????";
CustomDestinationDataProvider test = new CustomDestinationDataProvider();
//set properties for the destination and ...
myProvider.changeProperties(destName, getDestinationPropertiesFromUI());
//... work with it
test.executeCalls(destName);
}
public static void step4WorkWithTable(JCoDestination dest) throws JCoException
{
JCoFunction function = dest.getRepository().getFunction("BAPI_COMPANYCODE_GETLIST");
if(function == null)
throw new RuntimeException("BAPI_COMPANYCODE_GETLIST not found in SAP.");
try
{
function.execute(dest);
}
catch(AbapException e)
{
System.out.println(e.toString());
return;
}
JCoStructure returnStructure = function.getExportParameterList().getStructure("RETURN");
if (! (returnStructure.getString("TYPE").equals("")||returnStructure.getString("TYPE").equals("S")) )
{
throw new RuntimeException(returnStructure.getString("MESSAGE"));
}
JCoTable codes = function.getTableParameterList().getTable("COMPANYCODE_LIST");
for (int i = 0; i < codes.getNumRows(); i++)
{
codes.setRow(i);
System.out.println(codes.getString("COMP_CODE") + '\t' + codes.getString("COMP_NAME"));
}
//move the table cursor to first row
codes.firstRow();
for (int i = 0; i < codes.getNumRows(); i++, codes.nextRow())
{
function = dest.getRepository().getFunction("BAPI_COMPANYCODE_GETDETAIL");
if (function == null)
throw new RuntimeException("BAPI_COMPANYCODE_GETDETAIL not found in SAP.");
function.getImportParameterList().setValue("COMPANYCODEID", codes.getString("COMP_CODE"));
//We do not need the addresses, so set the corresponding parameter to inactive.
//Inactive parameters will be either not generated or at least converted.
function.getExportParameterList().setActive("COMPANYCODE_ADDRESS",false);
try
{
function.execute(dest);
}
catch (AbapException e)
{
System.out.println(e.toString());
return;
}
returnStructure = function.getExportParameterList().getStructure("RETURN");
if (! (returnStructure.getString("TYPE").equals("") ||
returnStructure.getString("TYPE").equals("S") ||
returnStructure.getString("TYPE").equals("W")) )
{
throw new RuntimeException(returnStructure.getString("MESSAGE"));
}
JCoStructure detail = function.getExportParameterList().getStructure("COMPANYCODE_DETAIL");
System.out.println(detail.getString("COMP_CODE") + '\t' +
detail.getString("COUNTRY") + '\t' +
detail.getString("CITY"));
}//for
}
}
This question already has answers here:
Mocking Files in Java - Mock Contents - Mockito
(3 answers)
Closed 6 years ago.
I have the following code:
public class FolderServiceImpl implements FolderService {
private static final Logger L = LoggerFactory.getLogger(FolderServiceImpl.class);
public int getStatus(String folderPath) {
int status = 0;
File folderStatusFile = new File(folderPath, ".folderstatus");
if (folderStatusFile.exists()) {
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(folderStatusFile));
String line = br.readLine();
status = Integer.parseInt(line);
} catch (Exception e) {
L.error("can't read file " + folderStatusFile.getAbsolutePath(), e);
status = 4;
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
L.warn("could not close reader ", e);
}
}
}
} else {
status = 3;
}
return status;
}
}
I want to test this method without creating actual files for every case. I should be using Java 1.7, JUnit 4, Mockito and/or PowerMockito.
Any ideas on how to do that?
I am talking about mocking either the data source or simply changeing the input for the method.
My test looks something like this:
`#Rule
public TemporaryFolder folder = new TemporaryFolder();
private FolderServiceImpl serviceToTest = new FolderServiceImpl();
private String folderPath;
#Before
public void setUp() {
folderPath = folder.getRoot().getAbsolutePath();
try {
folder.newFile(".folderstatus");
} catch (IOException e) {
e.printStackTrace();
}
}
#Test
public void shouldReturnFolderStatus3WhenFolderStatusIsNotFound() {
// given
deleteFolderStatusFile();
// actual
int status = serviceToTest.getFolderStatus(folderPath);
// expected
assertEquals(3, status);
}
#Test
public void shouldReturnFolderStatus4WhenTheStatusIsUnreadable() {
// given
writeStatusToTestFile("Test");
// actual
int status = serviceToTest.getFolderStatus(folderPath);
// expected
assertEquals(4, status);
}
#Test
public void shouldReturnFolderStatusInTheFile() {
// given
writeStatusToTestFile("1");
// actual
int status = serviceToTest.getFolderStatus(folderPath);
// expected
assertEquals(1, status);
}
private void writeStatusToTestFile(String status) {
Path file = Paths.get(folder.getRoot().getAbsolutePath(), ".folderstatus");
try {
Files.write(file, status.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
private void deleteFolderStatusFile() {
Path file = Paths.get(folder.getRoot().getAbsolutePath(), ".folderstatus");
try {
Files.delete(file);
} catch (IOException e) {
e.printStackTrace();
}
}`
Although the answer of #BenHeid may work I'd suggest to change to different approach.
IMHO when ever I use PowerMock(-ito) it is a surrender to bad design.
Also the PowerMock solution will confuse test coverage tools since it changes the Applications byte code after it has been instrumented for coverage measurement.
So the approach I'd prefer is to stick to Clean Code and OOP rules.
One of them is separation of concerns.
In your case the method creates some infrastructure classes (dependencies) to work with, namely FileReader and BufferedReader.
But the instantiation of (direct) dependencies is not a responsibility of a class containing business logic.
Therefore I'd suggest to refactor that code out into a separate class:
class ReaderFactory {
public BufferedReader createFor(File file) throws FileNotFoundException {
return new BufferedReader(new FileReader(file));
}
}
Your Class would change to this:
class FolderServiceImpl {
private static final Logger L = LoggerFactory.getLogger(FolderServiceImpl.class);
private final ReaderFactory readerFactory;
FolderServiceImpl(ReaderFactory readerFactory) {
this.readerFactory = readerFactory;
}
public int getStatus(String folderPath) {
int status = 0;
File folderStatusFile = new File(folderPath, ".folderstatus");
// try "with resource" takes care of closing the reader
try (BufferedReader br = readerFactory.createFor(folderStatusFile);) {
String line = br.readLine();
status = Integer.parseInt(line);
} catch (IOException e) {
status = 3;
} catch (Exception e) {
L.error("can't read file " + folderStatusFile.getAbsolutePath(), e);
status = 4;
}
return status;
}
}
And your Test would be this:
public class FolderServiceImplTest {
private static final String ANY_FILE_NAME = "";
#Rule
public MockitoRule mockitoRule = MockitoJUnit.rule();
#Rule
public ExpectedException thrown = ExpectedException.none();
#Mock
private ReaderFactory readerFactory;
#InjectMocks
FolderServiceImpl sut;
#Test
public void getStatus_FileNotExisting_returnStatus3() throws Exception {
// arrange
Mockito.doThrow(new FileNotFoundException("UnitTest")).when(readerFactory).createFor(Mockito.any(File.class));
// act
int status = sut.getStatus(ANY_FILE_NAME);
// assert
Assert.assertThat("status",status,CoreMatchers.equalTo(3));
}
#Test
public void getStatus_ValidFile_returnFileContentAsInt() throws Exception {
// arrange
BufferedReader bufferedReader = Mockito.mock(BufferedReader.class);
Mockito.doReturn(bufferedReader).when(readerFactory).createFor(Mockito.any(File.class));
Mockito.doReturn("4711").when(bufferedReader).readLine();
// act
int status = sut.getStatus(ANY_FILE_NAME);
// assert
Assert.assertThat("status",status,CoreMatchers.equalTo(4711));
}
}
You have to use something like this:
#RunWith(PowerMockRunner.class)
#PrepareForTest(tests.class)
public class test {
#Test
public void test() throws Exception {
File fileMock = Mockito.mock(File.class);
PowerMockito.whenNew(File.class).withArguments(Mockito.anyString(), Mockito.anyString()).thenReturn(fileMock);
FolderServiceImpl sut = new FolderServiceImpl sut ();
Mockito.when(fileMock.exists()).thenReturn(true);
sut.getStatus("");
// Your verifications..
}
}
Powermock will mock the File object which is created in the method getStatus of your class. With Mockito.when you can say what is the return value of folderStatusFile.exists() in your code.
EDIT
I have included the following two jars with maven, but you don't need to use maven: https://mvnrepository.com/artifact/org.powermock/powermock-module-junit4/1.4.6 and https://mvnrepository.com/artifact/org.powermock/powermock-api-mockito/1.4.9 and https://mvnrepository.com/artifact/org.mockito/mockito-all/1.10.19
so i've been sitting above this code for a while , ready the NullPointerException threads, and still can't figure out what is going wrong in my code, so i turn to you.
public class Main {
public static void main(String[] args){
/* Making catalog, loading last state */
Collection catalog = new Collection();
try {
catalog.readFromFile();
} catch (ClassNotFoundException | IOException e) {
e.printStackTrace();
}
catalog.addShip(new Ship("ABC123", "John", "Suzuki", 50));
}
}
And my Collection class looks like this:
public class Collection {
private List<Ship> shipList;
private String fileName = "catalog.txt";
private int income;
private int space;
public Collection() {
shipList = new ArrayList<Ship>();
income = 0;
space = 500;
File f = new File("catalog.txt");
if(!f.exists()) {
try {
f.createNewFile();
writeToFile();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public void addShip(Ship SHIP){
space -= SHIP.LENGTH;
income += SHIP.COST;
shipList.add(SHIP);
}
public Ship getShip(int INDEX){
return shipList.get(INDEX);
}
public void writeToFile() throws IOException {
FileOutputStream f = new FileOutputStream(fileName);
ObjectOutputStream out = new ObjectOutputStream(f);
out.writeObject(shipList);
out.close();
}
#SuppressWarnings("unchecked")
public void readFromFile() throws IOException, ClassNotFoundException {
FileInputStream f = new FileInputStream(fileName);
ObjectInputStream in = new ObjectInputStream(f);
shipList = (ArrayList<Ship>)in.readObject();
in.close();
}
public int getIncome(){
return income;
}
public int getSpace(){
return space;
}
}
My problem is, when i call in main catalog.addship() i get nullptr error. After following the console errors, it says i get the nullptrexc when i call the addShip() on the catalog, following from there i get the error when i add() a Ship to the Collection's shipList. So what i concluded, it is because the shipList in the Collection is uninitialized. But in the constructor i write shipList = new ArrayList<Ship>(); so it is clearly initialized.
The exception stacktrace is the following:
Exception in thread "main" java.lang.NullPointerException
at collection.Collection.addShip(Collection.java:31)
at main.Main.main(Main.java:100)
In your main method, you initialize the ArrayList properly. But then, you make a
catalog.readFromFile()
call. In the readFromFile() method, you re-initialize the ArrayList
shipList = (ArrayList<Ship>)in.readObject();
the in.readObject() is returning null. That is why your shipList variable is null.
Hope this helps!