We Keep Coding

JavaFX complex string binding

I'm new to JavaFX and was wondering if the Bindings API allowed an easier way to achieve the following. Consider a model that contains a database that may be null (because the database loads asynchronously) and a view that displays a label status reflecting the state of the database. If it is null it should say something like "Loading..." and if it isn't it should display how many items are in the database. It also would be great if the status could reflect the size of the database as it grows or shrinks.
So far, I understand that I could bind an integer property (size of the database) to the text property of the label by using a converter. This is fine, but I want the label to display more than the number. A localized string like "Loaded {0} items" precisely. And let's not forget that the database may still be null.
This is the solution I have in place
#Override
public void initialize(URL url, ResourceBundle bundle) {
// Initialize label with default value
status();
model.databaseProperty().addListener((obs, old, neu) -> {
// Update label when database is no longer null
status();
// Update label when size of database changes
neu.sizeProperty().addListener(x -> status());
});
}
public void status() {
if (model.database() == null) {
status.setText(bundle.getString("status.loading"));
} else {
String text = bundle.getString("status.ready");
int size = model.database().size();
text = new MessageFormat(text).format(size);
status.setText(text);
}
}
It works, but is there a way to do it with a chain of bindings, or at least part of it? I've seen how powerful (and lenghty) boolean bindings can be but I'm not sure something as flexible is possible with string bindings.

You can use Bindings.when, which is essentially a dynamic if/then binding:*
status.textProperty().bind(
Bindings.when(model.databaseProperty().isNull())
.then(bundle.getString("status.loading"))
.otherwise(
Bindings.selectInteger(model.databaseProperty(), "size").asString(
bundle.getString("status.ready")))
);
However, the above assumes bundle.getString("status.ready") returns a java.util.Formatter string, not a MessageFormat string. In other words, it would need to be "Loaded %,d items" rather than "Loaded {0,number,integer} items".
Bindings doesn’t have built-in support for MessageFormat, but if you really want to stick with MessageFormat (which is a legitimate requirement, as there are things MessageFormat can do which Formatter cannot), you can create a custom binding with Bindings.createStringBinding:
MessageFormat statusFormat = new MessageFormat(bundle.getString("status.ready"));
status.textProperty().bind(
Bindings.when(model.databaseProperty().isNull())
.then(bundle.getString("status.loading"))
.otherwise(
Bindings.createStringBinding(
() -> statusFormat.format(new Object[] { model.getDatabase().getSize() }),
model.databaseProperty(),
Bindings.selectInteger(model.databaseProperty(), "size")))
);
* Actually, it’s more like the ternary ?…: operator.

Making a label editable depending on a variable in an array

I am making a registration page but I am fairly new to Java, I have a combo box for peoples Titles such as "Mr, Mrs, Miss, etc" one of the options is "Other..." And I have a text field next to the combo box to specify your title, I would like the text field to not be editable unless someone selects "Other..." in the combo box, How would I do this?
What it looks like at the moment:
I can't see what I'm doing wrong?
TitleSpecifyChoiceField.setEditable(false);
TitleSpecifyChoiceField.setText("Please specify title...");
TitleChoice.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Mr", "Mrs", "Miss", "Ms", "Dr", "Other..." }));
TitleChoice.setToolTipText("");
TitleChoice.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent e) {
if (TitleChoice.getSelectedItem().equals("Other...")){
TitleSpecifyChoiceField.setEditable(true);
};

You would do this the same way you'd respond to any changes in a JComboBox -- by adding a listener to the JComboBox as per the Swing combo box tutorial. Inside the listener, change the setEnabled(...) setting on the JTextField depending on the selected item. i.e., by calling getSelectedItem() on the JComboBox and testing whether calling equalsIgnoreCase("other") is true.
Note that I recommend that you use setEnabled(...) not setEditable(...) as the former will give the user visual cues as to whether the JTextField should be edited or not.
Edit
Regarding your code:
TitleSpecifyChoiceField.setEditable(false);
TitleSpecifyChoiceField.setText("Please specify title...");
TitleChoice.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Mr", "Mrs", "Miss", "Ms", "Dr", "Other..." }));
TitleChoice.setToolTipText("");
TitleChoice.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent e) {
if (TitleChoice.getSelectedItem().equals("Other...")){
TitleSpecifyChoiceField.setEditable(true);
}
}
});
Some problems and issues:
Does your JComboBox use Strings or does it hold other types of items?
You will want to add debugging code into your code to try to isolate the problem. For instance, inside of your ItemListener, add a System.out.println(...) to print out the selected item to be sure that the listener is working as expected.
You are checking if the item .equals("Other..."), a String literal. Instead consider making a String constant, OTHER that the JComboBox uses and that you test in the listener to be sure that the tested String and and the displayed are the same.
Again, I suggest you use setEnabled(...) not setEditable(...).
You should learn and follow Java naming conventions including beginning all variable names with lower case letter as this will help us to better understand your code.
You should fix your posted code indentation so that it is regular and makes sense (note my code above vs yours). Why do you want to make it harder for folks who are trying to help you to understand your code? Your job is to make ours as easy as possible as we're all volunteers.
Create and post an sscce to get the best and fastest help.

Add a listener to the combo box. When the selected item changes, call setEditable() on the text field.

You could try adding an ItemListener to your JComboBox and (as #HovercraftFullOfEels suggested) use setEnabled as opposed to setEditable. For a general idea, you could do something like this:
JTextField textField = ...;
JComboBox<String> comboBox = ...;
comboBox.addItemListener(
new ItemListener(){
public void itemStateChanged(ItemEvent e){
final String selected = (String)comboBox.getSelectedItem();
textField.setEnabled(selected.equals("other"));
}
}
);
Or if you are using Java 8 you could use this:
JTextField textField = ...;
JComboBox<String> comboBox = ...;
comboBox.addItemListener(
e -> {
final String selected = (String)comboBox.getSelectedItem();
textField.setEnabled(selected.equals("other"));
}
);

Need to delete from multiple JLists instead of just the one

I have 3 jlists. I have a button that is used to delete a selected item from the Patient Jlist but I also need it to delete from my history Jlist and Invoices Jlist. I have it deleting from one but I dont know how to implement the code to delete from the history jlist and invoices jlist.
Here is my code to delete from 1 JList which works!:
JButton btnDeleteDB = new JButton("Delete From DB");
btnDeleteDB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
int selectedIndex = patientList1.getSelectedIndex();
if (selectedIndex != -1) {
int x = patientList.get(selectedIndex).getID();
String query =
"DELETE FROM `patienttable` WHERE `patientid` ='"+x+"' LIMIT 1";
try {
Connection con =
DriverManager.getConnection(
"jdbc:mysql://localhost:3306/denistassignment","root","");
Statement s = (Statement) con.createStatement();
s.execute(query);
} catch (Exception ex) {
ex.printStackTrace();
}
patientListModel.remove(selectedIndex);
patientList1.remove(selectedIndex);
}
}});
btnDeleteDB.setBounds(320, 500, 125, 23);
contentPane.add(btnDeleteDB);

Your code shows quite a few design flaws I'm afraid, I will list some before answering your question:
Remove the code which removes the item from the DB and the list from the ActionListener and place it in a private method so you have easy access to it from other listeners if needed, to enhance readability and to avoid code duplication.
You are not closing neither the DB connection nor the statement. Do so.
Don't catch general Exceptions, and don't just call e.printStackTrace() unless for explicit debug code which is removed before production.
patientList1.remove(selectedIndex); has nothing to do with removing an item from the JList, consult the JavaDoc of this method for details. In short, remove that line.
I suppose all your JLists are in the same class and you have member variables pointing to each. If so, then just locate the corresponding objects which should also be removed in your other JLists at the same time you are locating the index of the currently selected one. I don't know the details of your system, so maybe iterate over the other list items, compare IDs with the ID of the one you want to delete and then just call listXY.getModel().remove(indexOfItem) for each one you want to delete.

JTextField getText() not working

I've been looking all over, and i cant find anyone who can solve this problem. I'm making a game, and in that game, i have editable controls. the controls window is a seperate JFrame, and when i click the confirm button, it is supposed to write the items in the JTextFields (holding the controls) to a file. but that wasnt working, so instead i have it print the arraylist that holds the values. here is the code:
public void writeControls() {
ArrayList<String> al = new ArrayList<String>();
al.add(up.getText());
al.add(down.getText());
al.add(left.getText());
al.add(right.getText());
al.add(jump.getText());
al.add(duck.getText());
al.add(attack.getText());
for (int i = 0; i < al.size(); i++) {
System.out.println(al.get(i));
}
System.exit(0);
}
the problem is this: if i change the final JTextField attack or any other one for that matter, and click submit, the system prints out the default controls. for example, if the JTextFields have the values w,a,s,d,r,t,q and i change the value q to i, it prints out q. what am i doing wrong? thanks in advance!
EDIT 1:
code for the textfields, and the FILES.... is simply a string stored in a different class. the class setText() is below the textfields.
up = new JTextField(setText(FILES.controlsFileFinalDir, 1));
down = new JTextField(setText(FILES.controlsFileFinalDir, 2));
left = new JTextField(setText(FILES.controlsFileFinalDir, 3));
right = new JTextField(setText(FILES.controlsFileFinalDir, 4));
jump = new JTextField(setText(FILES.controlsFileFinalDir, 5));
duck = new JTextField(setText(FILES.controlsFileFinalDir, 6));
attack = new JTextField(setText(FILES.controlsFileFinalDir, 7));
public String setText(String fileDir, int lineNum) {
String txt = "";
txt = io.readSpecificLine(fileDir, lineNum);
txt = switchCase(txt);
return txt;
}
switchcase() is only taking what you have written in the text file that these are getting the values from, and translating them. so if the value is 0, it is turned into Space, etc. io.readSpecificLine(); is only to get the line of text from the file. does this help?
EDIT 2:
i just was dinking around and found out that if i set the JTextField text by using setText(""); then use getText(); it works. so the problem is that when i change it manually, and use getText(); it wont work. Why?

To update the text to a currently existing JTextField, I would establish the JTextField as a class variable, and create a setter/getter method to adjust it (which I'm assuming you're doing).
According to your methods, you would use something like:
up.setText(setText(FILES.controlsFileFinalDir, 7));
Edit: **The first setText is the JTextField.setText, the second setText is your public method you posted. I'm assuming your second getText() isn't working because you're probably not setting the text correctly.
Without seeing more code, I can't really give a better guess.

The main possibilities:
(1) The text fields have their editable property set to false.
(2) You are creating multiple copies of the JTextFields, then editing a new one on the screen, but referring to the old one when you get the value.
(3) You have a ValueChanged or LostFocus event handler that is resetting the text fields to their defaults
(4) It is actually JFormattedTextField not a JTextField

If I was you, I would try to debug the programm. You will probably do some Mistake in your code, you won't be able to see, by just checking the code.
For example in which order do you call the functions and so on, maybe you have a fault here, or maybe you have several threads, so you try to read the Textfields without even set them and so on ... It's hard to say without reviewing the whole Code.
So if you use eclipse you can follow this link for an explanation on how to debug: http://www.vogella.com/articles/EclipseDebugging/article.html
Netbeans or any other IDE should support debugging as well.

This may seem like a strange thing to suggest, but I think this is an issue with pointers. If you create a new string before passing it in, JTextField will be able to change it internally and return what you expect when asked for the modified value.
down = new JTextField("" + setText(FILES.controlsFileFinalDir, 2));
// or
down = new JTextField(new String(setText(FILES.controlsFileFinalDir, 2)));

You might want to try the following:
create a class Test.java
import java.util.ArrayList;
import javax.swing.JTextField;
public class Test implements Runnable {
private ArrayList<JTextField> textFields = null;
private ArrayList<String> stringList = null;
public Test(ArrayList<JTextField> textFields, ArrayList<String> stringList) {
this.textFields = textFields;
this.stringList = stringList;
}
#Override
public void run() {
for ( JTextField textField : this.textFields )
this.stringList.add( textField.getText() );
}
}
and then, at the place where you use the "getText() method .. "
do the following...
ArrayList<JTextField> textFields = new ArrayList<JTextField>();
// add all the JTextField to textFields
ArrayList<String> stringList = new ArrayList<String>();
Test test = new Test( textFields, stringList );
SwingUtilities.invokeLater( test );
// check if the stringList is populated.
If this work, then what I believe is that, for some reason, the JTextField hasn't finished
"setting" the text, and before it finishes your getText() was called. I've had similar problems before, and this solved my problem that time, but still, this might not be the perfect solution.

First, you should change your "setText()" method name to something like "getTextFromFile()" it would be more readable
Then, if you are setting and reading the new text in different threads, my bet is that the setText() is taking long to return, because it is accessing the file system, while the method that read the values run instantly
I would try to do run a little test:
public void test(){ // must be run after the JTextFields be initialized
up.setText("TEST")
System.out.println(up.getText());
up.setText(setText(FILES.controlsFileFinalDir, 1));
System.out.println(up.getText());
}
If the test() prints the correct values, then we can assume that if you set and read the new value in the same thread it works fine
The other test I would do is:
public void testThread(){
new Thread(){
public void run(){
while(true){
if(up!=null){
System.out.println(up.getText());
}
try{
Thread.sleep(1000);
}catch(Exception e){
e.printStackTrace();
}
}
}
}.start();
}
It will print the value of up each 1 second, so that you can see if after some time you get the new value. If it does, then the answer is: Your setText() is taking long to run and you are reading the value before the new value is set

SOLUTION
none of the above answers were working for me, so i finally decided to just start over with that class. the few things i changed were the way i made the JTextFields. I made them as an array instead of individual objects. Second is the way i put what they say. When i initialized them, i was unable to get them to create WITH the text in the parameters. so i had to do that seperately. i changed some of the method names so as to reduce future confusion, and it worked! so im not sure what was up with that, maybe it was the way i did it, maybe just a fluke. it happens sometimes, so im sorry for the delay and waste of your time! thanks for all the answers anyway!

Try this:
textbox.setText(setFile(args)); // your function for set file

Getting content from JTextFields created dynamically

I am learning Java with Swing and I have some problems with using JTextField. In my program I want to dynamically add a few JTextFields with some text:
while( (ln = bufFile.readLine()) != null ) {
// inIdPanel is JPanel
inIdPanel.add(new JTextField(ln));
}
And it works good. However, the content of these JTextFields can be modified by users, and later I want to call getText() from all of them. Is this possible? How can I do this?
I saw this question: Java Swing: JButton creates new JTextField(s) but this isn't enough to solve my problem (I think using arrays in my case is not a good idea but maybe I'm wrong).

The reason why you cannot call getText() is that you have not stored a reference to the JTextField when you created it. You will need to use an array or collection to store the JtextFields as you create them so you can call the method on them later. A collection will be easier than an array because you do not know how many lines you will read in so you want it to be able to grow.
List<JTextField> fields = new ArrayList<JTTextField>();
while( (ln = bufFile.readLine()) != null ) {
JTextField field = new JTextField(ln);
inIdPanel.add(field);
fields.add(field);
}
Then you can call the .getText() from all of them
for(JTextField field: fields){
System.out.println(field.getText());
}

For an easy solution, just add an ArrayList<JTextField> textFieldList and add to the code you posted:
while((ln = bufFile.readLine()) != null) {
textFieldList.add(new JTextField(ln));
inIdPanel.add(textFieldList.get(textFieldList.size()-1));
}
Then, when you want to access the text fields, you simply iterate through them, e.g.
for (JTextField jtf : textFieldList) {
/* Operate on jtf, call methods, etc */
}
You could replace the ArrayList with an array if there is a defined limit on how many text fields you could add, but the list is nice if that quantity is unknown.