Need Button advice

I have this code w/in my program:

Code:

---

    btnFirst.addActionListener(new ActionListener(){
              public void actionPerformed(ActionEvent ae){
        DVD dvd = (DVD)dvds.get(list.getSelectedIndex(0));
                                        //int index = list.getSelectedIndex();
                                        //if (index=0) index = dvds.size();
                                        //int index = (list.getSelectedIndex(0));
                                        list.setSelectedIndex(index);
    }
  });

---

I've tried several variations so that the button is grabbing the first DVD in my array which of course is "0" but I don't know where to put the zero, I have stuff commented out because I copied a button I have for "next".

Thanks!

Hi,

Firstly without all your code it is hard to help, I don't know what type the variable dvds is? You say it is an array but it looks more like a List of some type. If you want to just get the first entry then doing it like this should work:

Code:

---

DVD dvd = (DVD)dvds.get(0);

---

Although I'm not sure why you would only want to get the first entry each time you click the button :ehh:

It seems that what you had was correct, it looks like you have a JList that is populated with data from your List/Array. So then you would be able to get the exact entry that is selected in the JList by saying:

Code:

---

DVD dvd = (DVD)dvds.get(list.getSelectedIndex());

---

Which is what you had and seems like the most logical thing to do.

Hope This Helps

That helped ALOT!

Can you help me make a "Save" Button work?

If I have a list:

Code:

---

    dvds.add(new DVD("Batman","Action","9583",17.00,7,5.95,124.95));
    dvds.add(new DVD("Cinderella","Family","2734",19.00,8,7.60,159.60));
    dvds.add(new DVD("Friends","Comedy","9824",18.00,5,4.50,94.50));
    dvds.add(new DVD("Lost","Drama","9382",25.00,2,2.50,52.50));
    dvds.add(new DVD("OfficeSpace","Comedy","9821",20.00,5,5.00,105.00));
    dvds.add(new DVD("StarWars","Action","1245",10.00,5,5.00,55.00));
    dvds.add(new DVD("Superman","Action","3652",20.00,10,10.00,210.00));

---

How can I have a save button save this to a file that a load button can load it later?

THANK YOU!

Well firstly you need to decide how you are going to save it to a file, are you going to serialize the objects directly to the file or are you going to take the approach of writing the text out to a file and keeping one record per line.

I would suggest maybe writing out the records as text to the file as serializing them will mean that any changes to the class whose objects you are serializing will cause problems.

What you could do is write another class that deals with writing records to a file, have a method that takes a List/Array or whatever you are using (you still haven't said what you are using) and in that method loop over the collection and write each record out, after the record start a new line and so on. The field positions has to be consistent ie: if the name comes first and the year second then it must be like that for all rows.

In this same class you can have another method for reading records which will return a collection of your chosen type. You read in the records line by line and after reading in each line split the fields up and create your objects that you will add to your collection.

If you have further problems let me know

Here is my code. Hopefully this will give you a better idea of what is the best approach. Any examples you can provide me etc would be great.

Do not mind all my // it's because of me trying to make things work, trial and error os that the code is just a copy of some other button for now.

Oh and this part I just modified but it won't work any ideas?

Code:

---

btnSearch.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent ae){
                        String Search =
                        JOptionPane.showInputDialog("Enter name of Movie");
                //        int x =0;
                for(int x = 0; x < dvds.size(); x++)
                {
                  DVD dvd = (DVD)dvds.get(x);
  //if(dvd.title.equals(dvd.title))// or
                  if(dvd.title.equalsIgnoreCase(dvd.title))
                  {
          list.setSelectedIndex(x);
          break;
        }
        }
                if(x = dvds.size()) System.out.println("not found");
                }
  });

---

thanks!

Code:

---

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.JFrame.*;
import java.io.*;
class Testing
{
  java.util.List<DVD> dvds = new java.util.ArrayList<DVD>();



  JTextField tfTitle = new JTextField(15);
  JTextField tfGenre = new JTextField(15);
  JTextField tfProductNumber = new JTextField();
  JTextField tfPrice = new JTextField();
  JTextField tfQuantity = new JTextField();
  JTextField tfRestockFee = new JTextField();
  JTextField tfInventoryValue = new JTextField();
  DefaultListModel dlm = new DefaultListModel();
  JList list = new JList(dlm);
  public void buildGUI()
  {
    JButton btnLoadfile = new JButton("Load File");
    JButton btnAdd = new JButton("Add");
    JButton btnModify = new JButton("Modify");
    JButton btnDelete = new JButton("Delete");
    JButton btnSearch = new JButton("Search");
    JButton btnSave = new JButton("Save");
    JButton btnFirst = new JButton ("First");
    JButton btnPrevious = new JButton ("Previous");
    JButton btnNext = new JButton ("Next");
    JButton btnLast = new JButton ("Last");
    JPanel p1 = new JPanel(new BorderLayout());
    JPanel p = new JPanel(new GridLayout(7,2));
    p.add(new JLabel("DVD Title: "));
    p.add(tfTitle);
    p.add(new JLabel("Genre: "));
    p.add(tfGenre);
    p.add(new JLabel("Product Number: "));
    p.add(tfProductNumber);
    p.add(new JLabel("Price per Unit: "));
    p.add(tfPrice);
    p.add(new JLabel("Quantity on Hand: "));
    p.add(tfQuantity);
    p.add(new JLabel("Restocking Fee (5%): "));
    p.add(tfRestockFee);
    p.add(new JLabel("Inventory Value: "));
    p.add(tfInventoryValue);
    p1.add(p,BorderLayout.CENTER);
    JPanel p2 = new JPanel();
    JPanel p3 = new JPanel();
    p2.add(btnLoadfile);
    p2.add(btnAdd);
    p2.add(btnModify);
    p2.add(btnDelete);
    p2.add(btnSearch);
    p2.add(btnSearch);
    p2.add(btnSave);
    p3.add(btnFirst);
    p3.add(btnPrevious);
    p3.add(btnNext);
    p3.add(btnLast);
    p1.add(p2,BorderLayout.NORTH);
    p1.add(p3,BorderLayout.SOUTH);
    JFrame f = new JFrame("DVD Inventory");
    JLabel label = new JLabel ( new ImageIcon("test.gif"));
    f.getContentPane().add(label, BorderLayout.SOUTH);
    f.getContentPane().add(p1,BorderLayout.NORTH);
    JScrollPane sp = new JScrollPane(list);
    f.getContentPane().add(sp,BorderLayout.CENTER);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.pack();
    f.setLocationRelativeTo(null);
    dvds.add(new DVD("Batman","Action","9583",17.00,7,5.95,124.95));
    dvds.add(new DVD("Cinderella","Family","2734",19.00,8,7.60,159.60));
    dvds.add(new DVD("Friends","Comedy","9824",18.00,5,4.50,94.50));
    dvds.add(new DVD("Lost","Drama","9382",25.00,2,2.50,52.50));
    dvds.add(new DVD("OfficeSpace","Comedy","9821",20.00,5,5.00,105.00));
    dvds.add(new DVD("StarWars","Action","1245",10.00,5,5.00,55.00));
    dvds.add(new DVD("Superman","Action","3652",20.00,10,10.00,210.00));
    setList();
    f.setVisible(true);
    //f.setIconImage(new ImageIcon("Images/test.gif").getImage());
    btnAdd.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        dvds.add(new DVD(tfTitle.getText(),tfGenre.getText(),tfProductNumber.getText(),
                                Double.parseDouble(tfPrice.getText()),
                              Integer.parseInt(tfQuantity.getText()),
                              Double.parseDouble(tfRestockFee.getText()),
                              Double.parseDouble(tfInventoryValue.getText())));
        setList();
        clearTextFields();
              }
    });
    btnDelete.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        int index = list.getSelectedIndex();
        dvds.remove(index);
        setList();
        clearTextFields();
      }
    });

        btnModify.addActionListener(new ActionListener(){
              public void actionPerformed(ActionEvent ae){
            int index = list.getSelectedIndex();
        dvds.remove(index);
                dvds.add(new DVD(tfTitle.getText(),tfGenre.getText(),tfProductNumber.getText(),
                                        Double.parseDouble(tfPrice.getText()),
                                      Integer.parseInt(tfQuantity.getText()),
                                      Double.parseDouble(tfRestockFee.getText()),
                                      Double.parseDouble(tfInventoryValue.getText())));
                setList();
                clearTextFields();
                      }
    });
        btnFirst.addActionListener(new ActionListener(){
                      public void actionPerformed(ActionEvent ae){
                DVD dvd = (DVD)dvds.get(0);
                                                list.setSelectedIndex(0);
            }
          });
                btnLast.addActionListener(new ActionListener(){
                              public void actionPerformed(ActionEvent ae){
                                DVD dvd = (DVD)dvds.get(6);
                                                        list.setSelectedIndex(6);
                      }
            });

 // btnSave.addActionListener(new ActionListener(){
//                public void actionPerformed(ActionEvent ae){
//
//                      try
//                      {
//                        File file = new File("TestSave.txt");
//                        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(file)));
//                        out.println("a line");
//                        out.println("another line");
//                        out.close();//<---------very important
//                      }
//                      catch(IOException ioe){ioe.printStackTrace();}
//                    }
//                  }

                    //dvds.add(new DVD(tfTitle.getText(),tfGenre.getText(),tfProductNumber.getText(),
                    //                            Double.parseDouble(tfPrice.getText()),
                    //                          Integer.parseInt(tfQuantity.getText()),
                    //                          Double.parseDouble(tfInventoryValue.getText())));
//                        setList();
//                        clearTextFields();
//                              }
 //  });
    btnSearch.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent ae){
                        String Search =
                        JOptionPane.showInputDialog("Enter name of Movie");
                //        int x =0;
                for(int x = 0; x < dvds.size(); x++)
                {
                  DVD dvd = (DVD)dvds.get(x);
  //if(dvd.title.equals(dvd.title))// or
                  if(dvd.title.equalsIgnoreCase(dvd.title))
                  {
          list.setSelectedIndex(x);
          break;
        }
        }
                if(x = dvds.size()) System.out.println("not found");
                }
  });

    btnPrevious.addActionListener(new ActionListener(){
              public void actionPerformed(ActionEvent ae){
                DVD dvd = (DVD)dvds.get(list.getSelectedIndex());
                                        int index = list.getSelectedIndex()-1;
                                        if (index <0) index = dvds.size()-1;
                                        list.setSelectedIndex(index);
      }
    });
    btnNext.addActionListener(new ActionListener(){
                      public void actionPerformed(ActionEvent ae){
                                            DVD dvd = (DVD)dvds.get(list.getSelectedIndex());
                                              //int index = list.getSelectedIndex()+1;
                                              int index = (list.getSelectedIndex()+1) % dvds.size();
                                        list.setSelectedIndex(index);

    }
    });

    list.addListSelectionListener(new ListSelectionListener(){
      public void valueChanged(ListSelectionEvent lse){
        if(lse.getValueIsAdjusting() == false)
        {
          int index = list.getSelectedIndex();//<---
          if(index > -1)//<---
          {
            DVD dvd = (DVD)dvds.get(index);//<---
            tfTitle.setText(dvd.title);
            tfGenre.setText(dvd.genre);
            tfProductNumber.setText(dvd.productNumber);
            tfPrice.setText(""+dvd.price);
            tfQuantity.setText(""+dvd.quantity);
            tfRestockFee.setText(""+dvd.restockFee);
            tfInventoryValue.setText(""+dvd.inventoryValue);
          }
        }
      }
    });

}

  public void setList()
  {
    dlm.clear();
    for(int x = 0, y = dvds.size(); x < y; x++)
    {
      dlm.addElement((DVD)dvds.get(x));
    }
  }
  public void clearTextFields()
  {
    tfTitle.setText("");
    tfGenre.setText("");
    tfProductNumber.setText("");
    tfPrice.setText("");
    tfQuantity.setText("");
    tfRestockFee.setText("");
    tfInventoryValue.setText("");
    tfTitle.requestFocusInWindow();
  }


  public static void main(String[] args)
  {
    EventQueue.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}
class DVD
{
  String title;
  String genre;
  String productNumber;
  double price;
  int quantity;
  double restockFee;
  double inventoryValue;
  public DVD(String t,String g, String pn, double p, int q, double r, double i)
  {
    title = t; genre = g; productNumber = pn; price = p; quantity = q; restockFee = r; inventoryValue = i;
  }
  public String toString(){return title;}
}

---

Quote:

---

Originally Posted by llsmr777

Oh and this part I just modified but it won't work any ideas?

---

It's because you're comparing 'dvd.title' with itself instead of with 'search' :rolleyes:

The best performance improvement is the transition from the nonworking state to the working state ...
J. Osterhout

You mean on this line:

if(dvd.title.equalsIgnoreCase(dvd.title))

Actually the error I get is on this line:

if(x = dvds.size()) System.out.println("not found");

And if I remove this line - it compiles. then when I run the application and hit search a box comes up as expected asking me to enter the movie name but then when I enter the movie name - it does't go to the movie I've typed.

Thanks!

Quote:

---

Originally Posted by llsmr777

if(x = dvds.size()) System.out.println("not found");

---

maybe you mean:

Code:

---

if(x == dvds.size()) System.out.println("not found");

---

Actually this is what I have now and it compiles but when I run it, it doesn't do what I want it to do. When I enter a DVD it just goes to "0" the first DVD and then when I enter a DVD name that is not on the list - no error message comes up like I've specified.

Code:

---

btnSearch.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent ae){
                        String Search =
                        JOptionPane.showInputDialog("Enter name of Movie");
                int x =0;
        //        for (x=0; x=1; x=2; x=3, x=4, x=5,x=6, x=7; x<(7);x++)
        //        for (x=0; x=1; x=2; x=3; x=4; x=5;x=6; x=7;)
                for (x=0; x<(7);x++)
                //for(int x = 0; x < dvds.size(); x++)
                {
                  DVD dvd = (DVD)dvds.get(x);
  //if(dvd.title.equals(dvd.title))// or
                  if(dvd.title.equalsIgnoreCase(dvd.title))
                  {
          list.setSelectedIndex(x);
          break;
        }
        }
        if(x == dvds.size()) JOptionPane.showInputDialog("Movie not found.");

                }
  });

---

Thats because you are comparing the title of the dvd to itself:

Code:

---

if(dvd.title.equalsIgnoreCase(dvd.title))

---

which will always return true since you are comparing the title of the same dvd. Then after it has returned true and entered the if statement you break which will exit the for loop, so all you are doing is going through the first iteration of the for loop, entering the if statement which will always return true then exiting the whole for loop via the break statement. So you will never even get to the second iteration. Try removing the break statement and see what happens.

Quote:

---

Originally Posted by llsmr777

Actually this is what I have now and it compiles but when I run it, it doesn't do what I want it to do.

---

If you took the trouble to step through the code by hand, away from the computer, you'd spot these errors far quicker.

The value of a prototype is in the education it gives you, not in the code itself...
A. Cooper

I promise I have been stepping through it but I hardly even undersatnd java. Most of my code is via examples and just trying to modify it.

I have tried so many variations but I can't get it to find the DVD. I finally got the message DVD not found but even if I enter a valid DVD it doesn't find it?

Quote:

---

Originally Posted by llsmr777

but I hardly even undersatnd java. Most of my code is via examples and just trying to modify it.

---

Rather than spending hour upon hour randomly changing bits of code and then posting questions here and waiting for answers. You could have used the time to work through a tutorial of two by now and you would now have a much better understanding of Java; you would be a lot less frustrated; you wouldn't need to be trying to change someone elses code to get it to do what you want and you would be able to write your own code and know how to debug it. That's not to say you won't still get stuck from time to time but at least you'll have the knowledge to post precise questions and be better equiped to understand the answers.

My advice is to leave your program for a short while and learn the basics, then when you return to your program you'll find you can complete it fairly quickly.

I have gone through the tutorials several times actually not the entire thing of course because it's quite long. And I still can't even code based on examples.

I know that I should be comparing what the user inputs in my enter movie dialog but I dont know how to call that.

I will try to go to the tutorials yet again

Is this not correct?

if(dvd.title.equalsIgnoreCase(Search));

Is my code wrong in my for loop maybe?

Quote:

---

Originally Posted by llsmr777

I have gone through the tutorials several times actually not the entire thing of course because it's quite long.

---

Which tutorial are you using?

Quote:

---

Originally Posted by llsmr777

And I still can't even code based on examples.

---

Do you mean you don't understand the examples or that you can't write code that is similar to the examples?

I've been on a few websites but mostly on the java.sun website and my school book.

A little of both. I've only been given about 6 weeks to learn all this and its been tough. Out of about 15 students there are only 4 of us left. Everyone else dropped out.

Most of my code is just examples I've taken and tried to accomodate what I need. But it's been so hard that I haven't even done most of my assignment right I'm just trying to get some of it so I can get some credit.

Java is a required class for my degree but I havne' t used it and will never use is in my current job. Tha'ts not to say I wouuld never want to learn it because I do but it would need to be more paced and with more direction.

Quote:

---

I've only been given about 6 weeks to learn all this

---

OK, that's tough especially since I guess this isn't your only subject.

However my advice hasn't changed, look at how much time you've wasted by trying to get simple things to work. I realise they don't seem simple to you but that's because you don't understand the basics. Dlorde often posts the following quotation and for good reason.

"If I had eight hours to chop down a tree, I would spend 6 hours sharpening an axe... Anon".

BTW when do you have to hand this assignment in by?
Can you post the assignment question, your design and the code so far.

Well not only is this not my only subject but I also work full time plus I have 3 kids all school aged that always need help on their homework. My husband works swing so he's not able to assist me.

Anyways enough of my sob story. I really have been trying but even just reading the basics is hard to comprehend esp with no real direction since its an online class. i really think java needs to be instructor led.

I did post my code in an earlier post. The entire code.
I have to turn this in on Monday.

I have to have a program that lists DVD's, has a button for First, Last, Next, Previous, Save - to save to a file, Load - to load the file, Modify, Delete, and Search!

I have designed it to look right but haven't gotten all the buttons to work.
I also haven't exactly done the assignment right because I was supposed to use methods and subclasses to calculate a restock fee and total inventory. But I tried to fix it and I couldn't and since I have so little time I have to just move on and try to get as much of it to work as I can so I just hard coded the restock and entire inventory total. I'm sure I'll get docked big time but oh well. I have had to work on previous assignments because they were wrong and I think that the instructor is giving people time over the due date to redo things because of his drop out rate.

Quote:

---

Originally Posted by llsmr777

since its an online class.

---

I can see where that can be a problem. Plus having kids & already having a fulltime job...etc. I give a lot of people this link & for good reason: it covers just about all of the material in a Java Intro course AND more. It's an excellent guide for the novice programmer:

http://leepoint.net/notes-java/

I hope that helps. Starting out in Java can be tough (speaking from experirence). You have probably heard this before but it is really great advice: Dissect your problem into smaller programs and combine those programs to create your final product. You would be amazed of how simple something is when you do it this way.

Take this example programming problem:

"I want a program that will manage my bank account"

In the real world, that's about all the information you get.

Let's break that sentence down some:

Hmm...manage a bank account...what will I probably need?

*Maybe a couple of instance variables to hold quantity, price, account No. etc.
*Need some data structure to store these fields in
*How many methods should I use ? (withdraw method, deposit method, etc.)

Some helpful questions to ask yourself:

What "is" a bank account ?
What do you mean by managing an account?
Who will use this account ?
How will I know if I run out of money ?
Can I transfer funds to another account ?

Basically just take your DVD Assignment and ask these questions the same way.

Last but not least, code in small intervals...meaning don't spend 3 straight hours cranking code. Manage your time and code when you are well rested. That way you can reduce your mistakes and code more efficiently. I know this won't be easy with your current schedule but don't give up.

Keep posting and let us know how you are progressing. Monday is so far away, so stay focused and you will definitely complete this assignment.

Thanks for the post.
i booked mark the site and I am going to look over it later. Hopefully I can fix some of my code!
Thanks again!

Quote:

---

Originally Posted by llsmr777

Well not only is this not my only subject but I also work full time plus I have 3 kids...

---

Ok I can see your time is limited and you now only have a couple of days left so I would suggest you consider a different plan. I don't know how your assignment will be marked but I would hope a fair number of the marks will be for the analysis and design rather than just on whether the program works. If that is the case (and if it isn't the course is probably not worth passing) and given that writing code is not your strong point at the moment why don't you leave the coding and concentrate on coming up with a good design. By design I don't mean how the GUI looks, I mean defining the classes you need, how they relate to each other and the methods they have. This will give you a basic program structure which, if it's done well, will get you marks. Once you have all your classes and method definitions you can then add code to the methods that give the maximum impact for the minimum work, for example you can cut and paste your existing GUI code in so that the application displays a GUI.

If as many people have left the course as you say then they are going to be lenient with the marking else they'll end up with nobody, so you just need to do enough to allow the lecturer to feel he/she is justified in awarding you marks.

Taking a look at each required features:

First, Last, Next and Previous are all related - they move to a particular DVD and display it's contents. Therefore the code for each of these is basically the same. The only difference is how you move the index. First and Last move to one end or other of the list. Assuming the DVD's are stored in a sensible data structure such as an ArrayList then you either set the index to 0 or list.size()-1. Next and Previous simply increment or decrement the index and then check to ensure it's still in bounds, for example if the current index is 0 and Previous is pressed then check to see if it's less then 0 and if it is set it to list.size()-1. Once you have the new index all the methods do the same thing ie get the DVD at this index and display it's contents. You should aim to code these features.

Saving to and Loading from file is possibly too compliated for you so why not just display a message saying "Feature Not Implemented Yet". At least it will show the button is active and will give the impression that you've just run out of time rather than you didn't know how to do it. An even better approach would be to simulate file storage by saving to and loading from an ArrayList, this can be done very easily and as long as you add comments to explain what you've done so it doesn't look like you're trying to cheat I'm sure you get some marks.

Delete is easy. you know the current index so you just need to check the user meant to delete the DVD and then call list.remove(index). Then you need to check the index is still in bounds because if you've deleted the last DVD then the index will be off the end of the list. And finally get and display the DVD at this index.

Modify - you're already displaying the DVD's attributes in JTextFields so the values can be chanegd and when the Modify button is pressed you just need to read each text field and call the appropriate DVD.setXXX() method. It's the same basic code for each TextField so do one, get it working and then just copy the code.

Search is more difficult so given the time constraint I'd resort to the "Feature Not Implemented Yet" message.

Hope this is of some help and good luck.

well it's almost done.
I got all but load and save buttons to work
I really do appreicate all the time each of you have taken to post.
I think the instructor is being lenient because just to know that more than 1/2 your class has dropped has to look and feel bad!!
You're suggestions were really great too! Thank you!!