I have a JCheckBox defined as:
JCheckBox NewCB = new JCheckbox();
NewCB.setSelected(false);
NewCB.setMnemonic(KeyEvent.VK_C);
NewCB.addItemListener(this);
This Check Box is using an ItemLisener:
public void itemStateChanged(ItemEvent e) {
Object source = e.getItemSelectable();
if(source == NewCB) {TEST = "SELECTED"; System.out.println(TEST);}
}
I launch a JFrame when the program starts. If I add this CheckBox to the frame, it works fine. If I open a second JFrame, and add this Check Box to the 2nd frame, and the Object Source no longer works. Is there some other definition I need to make to get the Object source to read the check box name for any open frames?
First of all, you can't add a component to more than one parent; I'm not sure that's your problem though.
The thing you're calling the "name" of the checkbox isn't a property of the checkbox, but rather a property of a variable that points to the checkbox. The difference is important, because there could be many such variables. The checkbox doesn't know anything about the variables that point to it.
Given that, how do we solve the problem? You can set the "action command" of the checkbox, and then check that:
NewCB.setActionCommand("Fred");
// ...
if ("Fred".equals(((JCheckBox) source).getActionCommand())))
// ...
Related
I have a check box and when I create an Action script from the Netbeans' design, it creates a function like;
private void jCheckBox1ActionPerformed(java.awt.event.ActionEvent evt) {
total=8.99f;
xc = "XCheese";
exTop++;
calculateTotal(total);
updateTextArea();
}
This works perfectly, but I want to set everything to zero when the jCheckBox1 is unchecked, if I uncheck it the way the code is now, no changes appear.
It is an sample of code. Hope it will help you.
private void jCheckBox1ActionPerformed(java.awt.event.ActionEvent evt) {
if(checkBox.isSelected() ){
total=8.99f;
xc = "XCheese";
exTop++;
calculateTotal(total);
updateTextArea();
}else{
// set everything zero here.
}
}
Start by taking a look at How to Use Buttons, Check Boxes, and Radio Buttons
Basically, the ActionListener will be called when ever the check box is selected (checked) or unselected (unchecked). You need to check the state of the check box when ever the method is called.
Take a look at AbstractButton#isSelected which will tell you the (in this case) the checked state of the JCheckBox
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"));
}
);
I am pretty new in Java programming, I have been trying to solve this simple program
it reads user input, then the ADD button will simply display the typed string on the JList.
The remove button will simply remove the desired item in the JList.
I am quite confused how to put the action listener thing in the code, or get text whatever
it is. I'd really appreciate if you can help me solve this simple GUI.
It reads user input in JText (String) and when I click the add button (maybe action performed?) the String will be basically populated in JList. and the Remove button will
simply remove the selected String in JList.
Step 1
Bind the code to the specific event, using the addActionListener method.
button.addActionListener(new ActionListener({
public void actionPerformed(ActionEvent e)
{
// Bind the method to the button.
}
});
Step 2
Populate that method with the relevant code.
String value = jTextBox.getText();
// Grab the String value.
jListModel.addElement(value);
// And add it to the list model that informs the JList.
Altogether
button.addActionListener(new ActionListener({
public void actionPerformed(ActionEvent e)
{
String value = jTextBox.getText();
// Grab the String value.
jListModel.addElement(value);
// And add it to the list.
}
});
Useful Links
Here is a very good tutorial from Oracle detailing how to manipulate lists a million and one different ways.
So I have this project,
the source code is here.
When you run the project and goto Processing, there is a jcombobox there that is suppose to have an addActionListener.
p_customer_list = new JComboBox<>(customers_name);
pp_customer_list.setPreferredSize(new Dimension(360, 35));
panel_processing_header.add(pp_customer_list);
//pp_customer_list.addActionListener(this);
pp_customer_list.addActionListener (new ActionListener () {
public void actionPerformed(ActionEvent e) {
JComboBox tmpBox = (JComboBox) e.getSource();
int selected = tmpBox.getSelectedIndex();
pp_refresh_data(selected);
}
});
This is what I have so far, its suppose to find the selected index when the value of the combobox changes and pass it to pp_refresh_data() but for some reason it does not run (I tried putting a JOptionPane to see when the code is executed, and its only executed once when the program runs.)
Hard to tell from just a partial code snippet, but do you have 2 combos, one named "p_customer_list" and another named "pp_customer_list"?
This could be your problem. You may be adding the listener to the wrong combo, or you may be adding the wrong combo to your panel, or maybe you don't need two, or maybe...
Again, it's hard to tell from just a snippet.
I'm a newbie in Java/JavaFX (I began yesterday evening). I'm building a dynamic GUI (crud) reading off a MySQL database.
I managed to display the data in a table and add a button next to each row.
Since the number of buttons is variable, I want to define only a common eventhandler.
The problem is that whenever I use event.getSource() (it's an ActionEvent) and display it, I get something like "Button[id=0, styleClass=button].
Question 1: Is there any way I could put the id in a variable? I can't get it out of the object.
As far as I know, I have to use the id, since I can't do something like this "if(event.getSource() == somebutton) {...}" since every generated button had the same variable name.
Now, this is the loop (inside a method called make_buttons) that builds the buttons. n_buttons is the number of buttons I want to build.
for(int counter = 0; counter < n_buttons; counter++){
String newtext = new String("btn"+counter);
Button btn = new Button();
btn.setText(newtext);
btn.setId(Integer.toString(counter));
btn.setOnAction(myHandler);
grid.add(btn,0,counter);
}
Note that I'm placing the buttons on a gridpane one on top of the other.
Before that part I have my handler:
final EventHandler<ActionEvent> myHandler = new EventHandler<ActionEvent>(){
public void handle(final ActionEvent event) {
Object new_output = event.getSource();
System.out.println(new_output);
event.consume();
}
};
Question 2: so, how can I differentiate which button fired the event in my particular case?
I know quite a few programming languages (Matlab, R, Python, C, Assembly, etc... but I'm a hobbyist), but it's the first time I'm working with GUI elements (except web languages and ActionScript 3).
In actionscript I could just do something like event.getCurrentTarget and the use it exactly as if it were the object itself to read the id, properties, etc.
I looked everywhere and couldn't find anything (maybe my terminology was a bit approximative...).
If I understand your question correcty, you can simply access the clicked button in you handle method with the following code:
Object source = event.getSource();
if (source instanceof Button) { //should always be true in your example
Button clickedBtn = (Button) source; // that's the button that was clicked
System.out.println(clickedBtn.getId()); // prints the id of the button
}