Programming Forums > Application Development > Java

PaCkEtPiRaTe · Jun 28th, 2012, 12:34 PM

I'm writing a program which will calculate the percentage of each nationality you are based on the family tree you specify. I'm running into problems when reading in the list of nationalities from a file. I don't know if maybe I just put the file in the wrong folder, or if it's the way I read the file / the data type I'm using to store it, but when I pull up the dialog box that is supposed to show a drop down list with all the nationalities, it gives me what looks like an error as my only choice in the drop down.

Here is the function I use to read in the data:

 java Syntax (Toggle Plain Text) 
public Set<String> populateNationalities() throws FileNotFoundException {
    File inFile = new File("demonyms.txt");
    String line = "";
    Set<String> demonyms = new HashSet<>();
 
    BufferedReader reader = new BufferedReader(new FileReader(inFile));
 
    try {
        while((line = reader.readLine()) != null) {
            demonyms.add(line);
        }
 
        reader.close();
    } catch(IOException io) {
        System.err.println(io);
        System.exit(1);
    }
 
    return demonyms;
}
public Set<String> populateNationalities() throws FileNotFoundException {
    File inFile = new File("demonyms.txt");
    String line = "";
    Set<String> demonyms = new HashSet<>();
                
    BufferedReader reader = new BufferedReader(new FileReader(inFile));
        
    try {
        while((line = reader.readLine()) != null) {
            demonyms.add(line);
        }
            
        reader.close();
    } catch(IOException io) {
        System.err.println(io);
        System.exit(1);
    }
        
    return demonyms;
}

Now, here is the code snippet I used in the constructor to assign those values to the HashSet defined in the class:

 java Syntax (Toggle Plain Text) 
try {
    nationalities = populateNationalities();
} catch (FileNotFoundException ex) {
    System.err.println(ex);
    System.exit(1);
}
try {
    nationalities = populateNationalities();
} catch (FileNotFoundException ex) {
    System.err.println(ex);
    System.exit(1);
}

And finally, here is the function I use to add a nationality... it adds it to another HashSet which is in a class called Person, which is the class that the Tree is made of.

 java Syntax (Toggle Plain Text) 
public void addNationality() {
    if(nationalities != null) {
        Object[] demonyms = {nationalities.toArray()};
        String nationalityChoice = (String) JOptionPane.showInputDialog(this, "Choose a nationality.", "Nationalities", JOptionPane.INFORMATION_MESSAGE, null, demonyms, demonyms[0]);
        familyTree.getCurrent().getData().addNationality(nationalityChoice);
        updateLists();
    } else {
        System.err.println("Nationalities list could not be loaded.");
        System.exit(1);
    }
}
public void addNationality() {
    if(nationalities != null) {
        Object[] demonyms = {nationalities.toArray()};
        String nationalityChoice = (String) JOptionPane.showInputDialog(this, "Choose a nationality.", "Nationalities", JOptionPane.INFORMATION_MESSAGE, null, demonyms, demonyms[0]);
        familyTree.getCurrent().getData().addNationality(nationalityChoice);
        updateLists();
    } else {
        System.err.println("Nationalities list could not be loaded.");
        System.exit(1);
    }
}

When I update the list in the updateLists() function, I'm just retrieving the Person object from the current node in the tree and passing its nationality list's .toArray() value to the JList's setListData() method. So why is it giving me this error? (screenshots attached)

I probably just forgot to convert something somewhere, or maybe the file is in the wrong place? I put it in the folder with the compiled .class file (MainFrame.class), so I don't think that's it.

Anyone see something I'm not?

Sinus · Jun 28th, 2012, 1:32 PM

It's not an error. It just shows your Object as string. What about instead putting Object demonyms in JOptionPane, you'd put JComboBox which contains strings from demonyms?

PaCkEtPiRaTe · Jun 28th, 2012, 2:09 PM

I'm not exactly sure what you mean. What does a JComboBox have to do with my input dialog? It also shows these strings in my "Nationalities" JList if I navigate through the tree.

Sinus · Jun 28th, 2012, 2:45 PM

Sorry, my bad, try to replace Object with String in addNationality method.

PaCkEtPiRaTe · Jun 28th, 2012, 3:06 PM

The .toArray() method of the HashSet converts it to Object[]. I can't use String[]...

Sinus · Jun 28th, 2012, 3:56 PM

Have you tried debugging?

It is kinda strange, I've tried to run something similar on my JVM and it worked (or maybe missed something):

PaCkEtPiRaTe · Jun 28th, 2012, 9:34 PM

The only thing I could think of is maybe it's not reading the information from the file properly.

macteki · Jun 28th, 2012, 11:29 PM

Change this:

 java Syntax (Toggle Plain Text) 
      Object[] demonyms = {nationalities.toArray()};
      Object[] demonyms = {nationalities.toArray()};

to this:

 java Syntax (Toggle Plain Text) 
      String[] demonyms = nationalities.toArray(new String[]{});
      String[] demonyms = nationalities.toArray(new String[]{});

PaCkEtPiRaTe · Jun 29th, 2012, 12:38 AM

Well, I'm not really sure how it worked, but it did. I didn't see any versions of that method that took any arguments... what did it do differently? It fixed the input dialog, but the JList that shows each ancestor's nationalities is still showing those funny object strings.

macteki · Jun 29th, 2012, 1:36 AM

Quote:

Originally Posted by PaCkEtPiRaTe

Well, I'm not really sure how it worked, but it did.

It worked because showInputDialog() is expecting String array instead of Object array. If you passed an object array into it, the default "toString()" method would be called, which is implementation dependent.

Quote:

Originally Posted by PaCkEtPiRaTe

I didn't see any versions of that method that took any arguments... what did it do differently?

There are two method declaration for toArray() in java.util.Set

1. Object[] toArray()
Returns an array containing all of the elements in this set.

2. <T> T[] toArray(T[] a)
Returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array.

See this link for reference.

http://docs.oracle.com/javase/6/docs.../util/Set.html

Jun 28th, 2012, 2:09 PM	#3
PaCkEtPiRaTe Software Developer Join Date: Aug 2007 Location: Massachusetts, USA Posts: 696 Rep Power: 6	Re: Problem Reading a File I'm not exactly sure what you mean. What does a JComboBox have to do with my input dialog? It also shows these strings in my "Nationalities" JList if I navigate through the tree. __________________ I'm trying to change the world, but I can't find the source code...

Jun 28th, 2012, 2:45 PM	#4
Sinus Hobbyist Programmer Join Date: Jul 2011 Location: Lithuania Posts: 120 Rep Power: 2	Re: Problem Reading a File Sorry, my bad, try to replace Object with String in addNationality method.

Jun 28th, 2012, 3:06 PM	#5
PaCkEtPiRaTe Software Developer Join Date: Aug 2007 Location: Massachusetts, USA Posts: 696 Rep Power: 6	Re: Problem Reading a File The .toArray() method of the HashSet converts it to Object[]. I can't use String[]... __________________ I'm trying to change the world, but I can't find the source code...

Jun 28th, 2012, 3:56 PM	#6
Sinus Hobbyist Programmer Join Date: Jul 2011 Location: Lithuania Posts: 120 Rep Power: 2	Re: Problem Reading a File Have you tried debugging? It is kinda strange, I've tried to run something similar on my JVM and it worked (or maybe missed something):

Jun 28th, 2012, 9:34 PM	#7
PaCkEtPiRaTe Software Developer Join Date: Aug 2007 Location: Massachusetts, USA Posts: 696 Rep Power: 6	Re: Problem Reading a File The only thing I could think of is maybe it's not reading the information from the file properly. __________________ I'm trying to change the world, but I can't find the source code...

Jun 28th, 2012, 1:32 PM	#2
Sinus Hobbyist Programmer Join Date: Jul 2011 Location: Lithuania Posts: 120 Rep Power: 2	It's not an error. It just shows your Object as string. What about instead putting Object demonyms in JOptionPane, you'd put JComboBox which contains strings from demonyms?

Jun 28th, 2012, 11:29 PM	#8
macteki Professional Programmer Join Date: Jul 2011 Posts: 430 Rep Power: 2	Re: Problem Reading a File Change this: java Syntax (Toggle Plain Text) Object[] demonyms = {nationalities.toArray()}; Object[] demonyms = {nationalities.toArray()}; to this: java Syntax (Toggle Plain Text) String[] demonyms = nationalities.toArray(new String[]{}); String[] demonyms = nationalities.toArray(new String[]{}); __________________ API belongs to public. Knowledge belongs to yourself http://java.macteki.com

Jun 29th, 2012, 12:38 AM	#9
PaCkEtPiRaTe Software Developer Join Date: Aug 2007 Location: Massachusetts, USA Posts: 696 Rep Power: 6	Re: Problem Reading a File Well, I'm not really sure how it worked, but it did. I didn't see any versions of that method that took any arguments... what did it do differently? It fixed the input dialog, but the JList that shows each ancestor's nationalities is still showing those funny object strings. __________________ I'm trying to change the world, but I can't find the source code...

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Programming Forums > Application Development > Java

Problem Reading a File