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Junit Test case of method that already has a try-catch clause

I'm trying to write a test case for the method setTrailer() within the class ErParser. setTrailer() has try-catch clauses, and in one of its catch clauses, it catches NullPointerException. I'm trying to write a Junit test for the case where setTrailer() throws and catches a NullPointerException, but the test case keeps failing. Is it because I already caught the exception in the method itself? Should I be catching the exception in the test case instead?
The test case:
public class TestERParser {
#Test(expected=NullPointerException.class)
public void nullSetTrailer() {
ERParser recCurrParse = new ERParser();
recCurrParse.setTrailer(null);
}
}
setTrailer() method within the ERParser Class:
public class ERParser {
private static final String TRAILER_E = "GRAND TOTAL";
private static final String TRAILER_R = "TRAILER";
public String trailerRecord;
/**
* Constructs an ERParser object.
*/
public ERParser() {
this.trailerRecord = null;
this.trailerVals = null;
}
/**
* Populates the trailerRecord field with the summary (trailer) record of the input file.
* #param file Input file
* #throws NullPointerException, FileNotFoundException, IOException
*/
public void setTrailer(File file) {
try {
FileReader fReader = new FileReader(file);
BufferedReader bReader = new BufferedReader (fReader);
String currLine = new String();
readLoop:
while (bReader.ready()) {
currLine = bReader.readLine();
if (currLine.contains(TRAILER_E) || currLine.contains(TRAILER_R)) {
break readLoop;
}
}
this.trailerRecord = currLine.trim();
System.out.println("From setTrailer(): " + this.trailerRecord);
fReader.close();
bReader.close();
} catch (NullPointerException exception) {
exception.printStackTrace();
} catch (FileNotFoundException exception) {
exception.printStackTrace();
} catch (IOException exception) {
exception.printStackTrace();
}
}
}

As you suspected you are catching the NPE inside of your code and it is not being propagated. If you expected your users to catch this exception you should remove this code and adorn your method with throws, to the appropiate classes.
public void setTrailer(File file) throws Exception {
FileReader fReader = new FileReader(file);
BufferedReader bReader = new BufferedReader (fReader);
String currLine = new String();
readLoop:
while (bReader.ready()) {
currLine = bReader.readLine();
if (currLine.contains(TRAILER_E) || currLine.contains(TRAILER_R)) {
break readLoop;
}
}
this.trailerRecord = currLine.trim();
System.out.println("From setTrailer(): " + this.trailerRecord);
fReader.close();
bReader.close();
}
As your code now throws a checked Exception, you will need to update your Junit method slightly, to catch the checked exceptions
#Test(expected=NullPointerException.class)
public void nullSetTrailer() throws Exception {
ERParser recCurrParse = new ERParser();
recCurrParse.setTrailer(null);
}

We can argue about whether or not this catch block means the exception is handled. I would argue that merely printing the stack trace is not handling anything. It might be better to add a throws clause to the method signature and let clients decide what to do with exceptions.
If the method is written that way, it's up to you to test it as-written. You wouldn't have a choice if this was a 3rd party library.
Write the test that throws the exception; succes means trailerRecord is set to null.
Your code has another flaw: close the streams in a finally block. You risk not closing the input stream properly as written.

In your test case are expecting a NullPointerException class. If you catch it, the caller class will not get it. Hence, either you can remove the try/catch blocks or you can rethrow the exception after printing stacktrace :
catch (NullPointerException exception) {
exception.printStackTrace();
throw new NullPointerException();
}

Trying to save Custom Array of Objects Android

So I'm making a notepad application that logs date entered, a subject, and a body text field. When I hit my post button, everything appears properly in my ListView, but when I close the application and re-open it, only the date remains intact and the other two values are NULL. Below is the code I'm using.
public class LogList implements Serializable {
private String logDate;
private String logBody;
private String logSubject;
public LogList(String date, String LogBody, String LogSubject){
super();
this.logDate = date;
this.logBody = logBody;
this.logSubject = logSubject;
}
Back in my main class, I have my method that is supposed to save the three values into an ArrayList lts.
private void saveInFile(String subject_text, String date, String body_text ){
LogList lt = new LogList(date, subject_text, body_text);
lts.add(lt);
saveAllLogs();
}
Now if I change the order of the values in my new LogList, only the first one will be properly displayed after I close my app and reopen it. The following are my saveAllLogs method and my loadFromFile method.
private ArrayList<String> loadFromFile(){
ArrayList<String> logs = new ArrayList<String>();
try {
FileInputStream fis = openFileInput(FILENAME);
ObjectInputStream ois = new ObjectInputStream(fis);
while (true) {
LogList lt = (LogList) ois.readObject();
logs.add(lt.toString());
lts.add(lt);
}
}
catch (FileNotFoundException e) { e.printStackTrace(); }
catch (IOException e) { e.printStackTrace(); }
catch (ClassNotFoundException e) { e.printStackTrace(); }
return logs;
}
private void saveAllLogs() {
try {
FileOutputStream fos = openFileOutput(FILENAME, 0);
ObjectOutputStream oos = new ObjectOutputStream(fos);
for (LogList lti : lts) {
oos.writeObject(lti);
}
fos.close();
}
catch (FileNotFoundException e) { e.printStackTrace(); }
catch (IOException e) { e.printStackTrace(); }
}
Any help would be greatly appreciated!

For one thing,
public LogList(String date, String LogBody, String LogSubject){
super();
this.logDate = date;
this.logBody = logBody;
this.logSubject = logSubject;
}
Seems wrong. As you have capitalized argument names, but you're setting the members with lowercase names.
Do you mean:
public LogList(String date, String logBody, String logSubject){
super();
this.logDate = date;
this.logBody = logBody;
this.logSubject = logSubject;
}
EDIT: Trivial thing, not impacting your code: You don't need your call to super() in your constructor as you're not extending any class.

Java Serialization

I'm learning now how to do serialization using Java Language. I have read some posts and docs about the subject and I tried to do a simple example (below)
public class SterializeObject implements java.io.Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
private String name;
private transient int code;
public SterializeObject (String n, int c){
name = n;
code = c;
}
public void printAtributes (){
System.out.println("name: " + name + "; code: " + code);
}
}
public class MainClass {
public static void main(String[] agrs) {
SterializeObject ob1 = new SterializeObject("ana", 1);
SterializeObject ob2 = new SterializeObject("rita", 2);
try {
FileOutputStream fileOut = new FileOutputStream("file.data");
ObjectOutputStream outObj = new ObjectOutputStream(fileOut);
outObj.writeObject(ob1);
outObj.writeObject(ob2);
outObj.close();
System.out.println("Objects were serialized!");
} catch (IOException e) {
e.printStackTrace();
}
ArrayList<SterializeObject> list = new ArrayList<SterializeObject>();
try {
FileInputStream fileInput = new FileInputStream("file.data");
ObjectInputStream inputObj = new ObjectInputStream(fileInput);
Object o;
try {
while ((o = inputObj.readObject()) != null) {
list.add((SterializeObject) o);
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("Erro foi aqui! (1)");
}
inputObj.close();
fileInput.close();
} catch (IOException e) {
e.printStackTrace();
System.out.println("Erro foi aqui! (2)");
}
for (int i = 0; i < list.size(); ++i) {
list.get(i).printAtributes();
}
}
}
I created a Class SterializeObject that implements java.io.Serializable with two variables: one string (name) and one int (code) that is transient. Then In the main I generate two instances of that class and I tried to write it in a file, that I have done successfully! After that, I try to read the two object with a Loop.. there is my problem.. since the ObjectInputStream dosen't have some kind of method to see if we are in the end or not. So, I tried to do with this condition: (o = inputObj.readObject()) != null.
My output is this:
java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at MainClass.main(MainClass.java:30)
Objects were serialized!
Erro foi aqui! (2)
name: ana; code: 0
name: rita; code: 0
I get the objects, but I get an error because, I think, is trying to access to something that doesn't exist.
Someone can tell me other way to do it?
Best Regards.

Read as many objects as the number of written objects, or write the list of objects itself, instead of writing every object one after the other.
(Or rely on the EOFException to detect the end of the stream, but this is ugly).

As many of you told me to do, I created a ArrayList and serialized the ArrayList.
My code is:
public class MainClass {
public static void main(String[] agrs) {
SterializeObject ob1 = new SterializeObject("ana", 1);
SterializeObject ob2 = new SterializeObject("rita", 2);
ArrayList <SterializeObject> list = new ArrayList<>();
list.add(ob1);
list.add(ob2);
ArrayList <SterializeObject> input = new ArrayList<SterializeObject>();
try {
FileOutputStream fileOut = new FileOutputStream("file.data");
ObjectOutputStream outObj = new ObjectOutputStream(fileOut);
outObj.writeObject(list);
outObj.close();
System.out.println("Objects were serialized!");
} catch (IOException e) {
e.printStackTrace();
}
try {
FileInputStream fileInput = new FileInputStream("file.data");
ObjectInputStream inputObj = new ObjectInputStream(fileInput);
Object o;
try {
input = (ArrayList<SterializeObject>) inputObj.readObject();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("Erro foi aqui! (1)");
}
inputObj.close();
fileInput.close();
} catch (IOException e) {
e.printStackTrace();
System.out.println("Erro foi aqui! (2)");
}
for (int i = 0; i < input.size(); ++i) {
input.get(i).printAtributes();
}
}
}
And the output is:
Objects were serialized!
name: ana; code: 0
name: rita; code: 0
Thank you for the help!

Close the FileOutputStream also along with ObjectOutputStream
fileOut.close();

Why don't you add both object to an ArrayList, and serialize the ArrayList. Then you just have to Deserialize the ArrayList and it will be populated with both objects.

You can do this by placing the readObject call inside a try-catch block and catching that EOFException you get, signaling you have read all the objects.

Replace your while loop with this piece of code
do{
try
{
o = inputObj.readObject();
list.add((SterializeObject) o);
}
catch(EOFException e)
{
o = null;
}
}while (o != null);

Return in a 'finally' statement

I'm trying to read ObjectOutputStream from a file and convert it to an arraylist.
This whole thing is happening inside a method which should read the file and return the array list:
public static List<Building> readFromDatabase(){
String fileName="database.txt";
FileInputStream fileIStream=null;
ObjectInputStream in=null;
List<Building> buildingsArr=null;
try
{
fileIStream = new FileInputStream(fileName);
in = new ObjectInputStream(fileIStream);
buildingsArr=(ArrayList<Building>)in.readObject();
}
catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
Console.printPrompt("ArrayList<Building> class not found.");
e.printStackTrace();
}
finally{
Console.printPrompt("Closing file...");
close(in);
close(fileIStream);
return buildingsArr;
}
}
Java tells me that this is dangerous.
What are the alternatives?
I can't put the return in the "try" block because it won't do it / it won't close files in the "finally" block.
I need to both make sure files will be closed, and return the array list I created as well.
Any ideas?

I can't put the return in the "try" block because it won't do it / it
won't close files in the "finally" block.
Wrong, finally block would still execute if you put return in try block. Thus you can return in your try block.
try
{
//your code
return buildingsArr;
}
catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
Console.printPrompt("ArrayList<Building> class not found.");
e.printStackTrace();
}
finally{
Console.printPrompt("Closing file...");
close(in);
close(fileIStream);
}

I would suggest starting to use Java 7, and the try with resources clause. http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
Ex:
static String readFirstLineFromFile(String path) throws IOException {
try (BufferedReader br = new BufferedReader(new FileReader(path))) {
return br.readLine();
}
}

You must either throw an Exception or return a value:
All you need to prove this is comment out the return "File Not Found" after the finally block and see that it won't compile.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
public class ReturnFinallyExample
{
public static void main(final String[] args)
{
returnFinally();
}
private static String returnFinally()
{
try
{
final File f = new File("that_does_not_exist!");
final FileInputStream fis = new FileInputStream(f);
return "File Found!";
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
finally
{
System.out.println("finally!");
}
return "File Not Found!";
}
}
You must have the return after the finally or you have to either:
declare the method to throws FileNotFoundExceptoin and re-throw the FileNotException out.
or
wrap the FileNotFoundException with throw new RuntimeException(e)

EOFException in Java Android? Help needed

I am trying to do some kind of serialization where I can directly read and write objects from file.
To start of I just tried to write a character to file and tried to read it. This keeps giving me EOF exception always.
I am trying it on a Android device. Here is my code:
public class TestAppActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
WriteToFile();
Load();
} catch (Exception e) {
e.printStackTrace();
}
}
public void Load () throws IOException
{
InputStream fis;
ObjectInputStream in = null;
try {
fis = new FileInputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
in = new ObjectInputStream(fis);
char temp = in.readChar();
} catch (IOException e) {
e.printStackTrace();
} finally {
in.close();
}
}
public static void WriteToFile() throws Exception {
try {
OutputStream file = new FileOutputStream(Environment.getExternalStorageDirectory() + "\\test2.ser");
ObjectOutput output = new ObjectOutputStream(file);
try {
output.writeChar('c');
} finally {
output.close();
}
} catch (IOException ex) {
throw ex;
}catch (Exception ex) {
throw ex;
}
}
}

In this case, EOFException means there is no more data to be read, which (again in this case) can only mean that the file is empty.
Why are you using ObjectInput/OutputStreams but only writing chars? You'd be better off with DataInput/OutputStreams for that usage.
Also there is no point in catching exceptions only to rethrow them.
Also there is no point in reading a char from a file unless you are going to put it somewhere other than in a local variable that isn't even returned by the method.

I have imported this code in my sample project with following change.
i replaced "\\test2.ser"with "/test2.ser" and it worked. please try this.