I'm writing code in a JPanel, it's all working fine. However, the categories are not displayed when I view the panel.
Here's the code I wrote:
for(Category c : categories){
comboModel.addElement(c);
NoResultsLabel.setVisible(false);
}
CategoriesCombo.setModel(comboModel);
So that in the customized code inside the design I write the following:
CategoriesCombo.setModel(comboModel);
However, the categories still don't show in the combobox.
Do you try to change NoResultsLabel.setVisible(false); to NoResultsLabel.setVisible(true); and let us know if your problem is solved
NoResultsLabel.setVisible(false); to NoResultsLabel.setVisible(true);
make sure your loop is ok,i mean Categories and Category class and
make sure your CategoriesCombo is a JComboBox type and then add your ComboBox to Jpanel
then use DefaulComboBoxModel for give a model to ComboBox
like this :
class test extends JFrame{
private JComboBox combo;
private final DefaultComboBoxModel model;
private Jpanel panel;
test()
{
combo = new JComboBox();
model = new DefaultComboBoxModel();
panel = new Jpanel();
createModel();
combo.SetModel(model);
panel.add(Combo);
add(panel);
}
void createModel()
{
for(Category c : categories){
model.addElement(c);
NoResultsLabel.setVisible(false);
}
public static void main(String[] args)
{
test t = new test();
}
}
Related
So i am making a shop system with a gui. I have a menu item that when i press it opens another jframe to input the number of each item sold in a jtextfield, like this:
JPanel salesPanel = new JPanel();
setSize(new Dimension(520,270));
setResizable(false);
setLocation(200,200);
title = new JLabel("<html><u><b>Fill in the number of products sold.</b></u></html>");
salesPanel.setSize(new Dimension(230,30*sw.getProductList().size()));
salesPanel.setLayout(new GridLayout(sw.getProductList().size()+1,3));
...
sw.getProductList().forEach(n ->{
salesPanel.add(new JLabel(Integer.toString(n.getProductID())+":"));
salesPanel.add(new JLabel(Integer.toString(n.getQuantity())));
salesPanel.add(new JLabel(n.getName()));
salesPanel.add(new JTextField());
});
This is how it looks.
Note that sw is the object of the main class which has an ArrayList of the type product which contains the information of each product.
Is there any way that I can text from these JTextFields ? And if not what is another way that I can do this.
EDIT:
in the main ShopWindow class, I have an ArrayList
private ArrayList<Product> productList = new ArrayList<Product>();
class product:
public class Product {
private int productID;
private String name;
private double price;
private int quantity;
private boolean isPerishable;
private double totalProdValue;
...getters and setters for each field
This is a mock solution (only meant to show how to update qty label and clear fields using action listeners)
public class MockFrame {
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel framePanel = new JPanel();
ProductPanel bananaPanel = new ProductPanel("268", "25", "Bananas");
ProductPanel sugarPanel = new ProductPanel("321", "200", "Sugar");
JPanel buttonPanel = new JPanel();
JButton update = new JButton("Update");
JButton cancel = new JButton("Cancel");
buttonPanel.setSize(400, 30);
update.setSize(50, 20);
cancel.setSize(50, 20);
buttonPanel.add(update);
buttonPanel.add(cancel);
update.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
bananaPanel.setNewQty();
sugarPanel.setNewQty();
}
});
cancel.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
bananaPanel.clearField();
sugarPanel.clearField();
}
});
frame.setSize(400, 400);
framePanel.setLayout(new BoxLayout(framePanel, BoxLayout.PAGE_AXIS));
framePanel.add(bananaPanel);
framePanel.add(sugarPanel);
framePanel.add(buttonPanel);
frame.add(framePanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
private static class ProductPanel extends JPanel {
private JLabel productId = new JLabel();
private JLabel qty = new JLabel();
private JLabel name = new JLabel();
private JTextField field = new JTextField();
public ProductPanel(String id, String amount, String itemName) {
this.setSize(400, 30);
this.field.setSize(100, 20);
this.field.setColumns(5);
productId.setText(id);
qty.setText(amount);
name.setText(itemName);
this.add(productId);
this.add(qty);
this.add(name);
this.add(field);
}
public void clearField() {
field.setText("");
}
public void setNewQty() {
String newQty = field.getText();
if (newQty != null && !newQty.isBlank()) {
qty.setText(newQty);
}
}
}
}
Main points of this mocked solution:
Use a JPanel to encapsulate a product line item. This will make it easier if you need to remove and/or add product rows.
The product panel contains a method to update qty or clear the fields that will be invokable by the frame buttons (depending on which is clicked).
Simplicity of design - Creating a generic panel for the product eliminate repetitive code.
Obviously, you would have to modify this so that you use the proper layout manager or use absolute positioning to properly aligned components to your liking. Also, you would need to create a Panel for the table header and add the remaining of your products. Also, you may want to break this into public classes and even maybe create a separate class for your frame.
The action listeners could also have a "for-each" loop to update each ProductPanel instead of hard coding each panel individually. That should look something like this:
public void actionPerformed(ActionEvent e) {
JPanel panel = (JPanel)((JButton) e.getSource()).getParent().getParent();
Component[] components = panel.getComponents();
for (Component c : components) {
if (c instanceof ProductPanel) {
((ProductPanel)c).setNewQty();
}
}
}
});
Obviously, your solution will depend on how you decide to encapsulate your components in containers. For this mock, the product panels are inside the frame panel which contains the panels where the buttons were placed. Therefore, I need to get the "grandparent" container for the update and cancel buttons to take advantage of calling the appropriate methods to update and clear in a more dynamic way.
Lastly, you may want to do something more elegant for creating your product panels. For example, you may want to add some factory method to create your product panel instead of having hard-coded product panels like my mock solution. Anyway, I think I demonstrated the solution you were looking for.
UPDATE: If you don't follow Andrew Thompson's recommendation of not using text fields for numeric values, the panel's getNewQty method would need to validate the text obtained to make sure it contains a valid numeric value (which was his point). I would STRONGLY recommend you follow his advice.
I managed to put this GUI together by adapting code from a book. I'm not sure how to implement listeners into this code since it is above my level, but I need them to make testing my program easier. I've looked through the posts on this site that are similar, however no one used the same code structure as me and I'm not sure how to implement the solutions on those posts.
So far I've tried using JCheckbox.addActionListener(this); which is what the oracle website said. Where ever I place this statement I get a variety of errors and I'm not sure why.
package inputform;
import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionListener;
public class Traitform extends JFrame implements ActionListener{
JPanel row1 = new JPanel();
JCheckBox eye1 = new JCheckBox("Brown");
JCheckBox eye2 = new JCheckBox("Blue");
JCheckBox eye3 = new JCheckBox("Green");
JCheckBox eye4 = new JCheckBox("Hazel");
JPanel row2 = new JPanel();
JCheckBox hair1 = new JCheckBox("Brown");
JCheckBox hair2 = new JCheckBox("Blonde");
JCheckBox hair3 = new JCheckBox("Ginger");
JCheckBox hair4 = new JCheckBox("Black");
JPanel row3 = new JPanel();
JCheckBox eye5 = new JCheckBox("Brown");
JCheckBox eye6 = new JCheckBox("Blue");
JCheckBox eye7 = new JCheckBox("Green");
JCheckBox eye8 = new JCheckBox("Hazel");
JPanel row4 = new JPanel();
JCheckBox hair5 = new JCheckBox("Brown");
JCheckBox hair6 = new JCheckBox("Blonde");
JCheckBox hair7 = new JCheckBox("Ginger");
JCheckBox hair8 = new JCheckBox("Black");
public Traitform () {
super("Parent Trait Form");
setSize(1000, 1000);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GridLayout layout = new GridLayout(0,1);
setLayout(layout);
row1.add(eye1);
row1.add(eye2);
row1.add(eye3);
row1.add(eye4);
row3.add(eye5);
row3.add(eye6);
row3.add(eye7);
row3.add(eye8);
row2.add(hair1);
row2.add(hair2);
row2.add(hair3);
row2.add(hair4);
row4.add(hair5);
row4.add(hair6);
row4.add(hair7);
row4.add(hair8);
add(row1);
add(row2);
add(row3);
add(row4);
setVisible(true);
}
private static void setLookAndFeel() {
try{
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Exception exc){
}
}
public static void main(String[] arguments){
Traitform.setLookAndFeel();
Traitform frame = new Traitform();
}
#Override
public void actionPerformed(ActionListener e){
System.out.println("action");
}
}
I need this program to take the user input from the check boxes so that it can be used in another part of my program in a separate package. When I run the current code I get the error uncompilable program.
This is clearly wrong:
JCheckbox.addActionListener(this);
addActionListener is not a static method. Also you probably want to do different things when different checkboxes are checked.
So you should do something like this:
hair5.addActionListener(() -> {System.out.println("hair5 clicked")});
You can also add single action listener for all checkboxes. For example put all your checkboxes in a list then do something like:
ActionListener myActionListener = () -> {System.out.println("my action listener")}
for (checkbox: checkboxList) {
checkbox.addActionListener(myActionListener);
}
The argument of addActionListener() method is an ActionListner (see doc).
So too use eye1.addActionListener(this); (for example) this need to be an ActionListner. ActionListener is an interface, which means this this needs to implement ActionListener.
this , in your case is traitform class (which should be Traitform see Java naming conventions) :
After changing the class definition to
public class Traitform extends JFrame implements ActionListener{
You need to add the implementation. In this case it is one method:
#Override
public void actionPerformed(ActionEvent e) {
// what ever you write here is invoked when action listener is used.
System.out.println("Action listener fired !");
}
Following the example above (eye1.addActionListener(this);), the actionPerformed method is invoked when eye1 fires an ActionEvent.
I have to add dynamically jcheckboxes in a panel when the user write something into a form. That's my code
Main
public class EmptyFrame extends JFrame{
private static final long serialVersionUID = 1L;
/*top panels*/
//to add technicians
private JButton newTechnician;
private NewTechForm ntForm;
private JPanel panelForm;
private JPanel panelChekBoxes;
TechCheckBoxGroup techniciansGroup;
private List<String> technicians;
//main container
private Container pane = getContentPane();
//components
GroupLayout gl = new GroupLayout(pane);
EmptyFrame(){
preinit();
init();
}
private void preinit(){
panelChekBoxes=new JPanel();
panelForm=new JPanel();
techniciansGroup=new TechCheckBoxGroup(panelChekBoxes);
}
private void init(){
/*top options*/
ntForm=new NewTechForm(panelForm);
newTechnician=new JButton("Add technician");
newTechnician.addActionListener(
new AddTechnicianAction(techniciansGroup,ntForm)
);
ntForm.getPanel().add(newTechnician);
/*end top options*/
for(String technic : technicians){
techniciansGroup.addCheckBoxes(
new JCheckBox(technic));
}
createWindowLayout(
new JLabel("Technicians"),
techniciansGroup.getCheckBoxes(),
ntForm.getPanel());
}
public void createWindowLayout(JComponent... arg) {
pane = getContentPane();
gl = new GroupLayout(pane);
pane.setLayout(gl);
gl.setAutoCreateContainerGaps(true);
gl.setAutoCreateGaps(true);
gl.setHorizontalGroup(gl.createParallelGroup()
.addGroup(gl.createSequentialGroup()
.addComponent(arg[0])
.addComponent(arg[1])
.addComponent(arg[2])
)
);
gl.setVerticalGroup(gl.createSequentialGroup()
.addComponent(arg[0])
.addGroup(gl.createParallelGroup()
.addComponent(arg[0])
.addComponent(arg[1])
.addComponent(arg[2]))
);
pack();
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
EmptyFrame ex = new EmptyFrame();
ex.setVisible(true);
});
}
}
in the main are presents a form and a checkbox group the first is the ntForm and the second one is the techniciansGroup. When i insert a name inside the form i would like to add a checkbox inside the checkbox group, here are the button, the checkbox group and the form classes:
AddTechnicianAction
this would be the class where everything would happened
public class AddTechnicianAction implements ActionListener{
TechCheckBoxGroup technicians;
NewTechForm form;
JTable table;
public AddTechnicianAction(TechCheckBoxGroup arg0, NewTechForm arg1){
technicians=arg0;
form=arg1;
}
#Override
public void actionPerformed(ActionEvent arg0) {
System.out.println("Add new tech: "+this.form.getSurnameText().getText()+" "+this.form.getNameText().getText());
technicians.addCheckBoxes(new JCheckBox(this.form.getSurnameText()+" "+this.form.getNameText()));
System.out.println(technicians);
}
}
NewTechForm
this is the form
public class NewTechForm {
private JLabel nameLabel;
private JLabel surnameLabel;
private JTextField nameText;
private JTextField surnameText;
private JPanel panel;
public NewTechForm(JPanel panel){
nameLabel= new JLabel("Nome: ", JLabel.RIGHT);
surnameLabel = new JLabel("Cognome: ", JLabel.CENTER);
nameText = new JTextField(6);
surnameText = new JTextField(6);
this.panel=panel;
panel.add(nameLabel);
panel.add(nameText);
panel.add(surnameLabel);
panel.add(surnameText);
}
public JLabel getNameLabel() {
return nameLabel;
}
public JTextField getNameText() {
return nameText;
}
public JTextField getSurnameText() {
return surnameText;
}
public JLabel getSurnameLabel() {
return surnameLabel;
}
public JPanel getPanel() {
return panel;
}
}
The problem is that inside TechCheckBoxGroup something happens, but not the things that i'm expecting to. The panel have a new checkbox after the action is performed but it seems that that panel (the obne inside TachCheckBoxGroup) is not the one inside the main class, and infact nothing were rendered in the window. There is clearly something that i didn't understand about the scoping in swing, what's the better practice to do what i'm trying to? Or this is the good way and i miss something?
I think that it is important to have answers on stack overflow, so for that reason I post my answer to my problem even if it's not really easy to see that was the right solution, now I explain better. While I'm trying to solve the problem of the wrong behaviour I've asked my self if I was doing the wrong considerations, and so it was, because i was trying to let comunicate all the components without a real
mediator
in fact it was impossible to catch the event in the main window with the code that i had written above. Seaching and searching i finally find this great answer here. So i basically change the NewTechForm classes making it a jpanel with a form inside, same thing for the CheckGroupBox, i'll made it a panel with the check box inside, and i send all the event to a listener in the main window.
Very new to Java, but I am slowly picking my way through things. So please be kind. I understand most things I've tried so far, and built a version of the following that uses console output, but now I'm trying to make a GUI. I tried the netbeans GUI maker, but it created so much new code that when I tried to pick through it, I got lost. I'm much better at learning by piecing new things together myself, not having an IDE generate a ton of code and then attempt to find where I want to work.
I am trying to build an window that has a list with three choices on the left side, a button in the middle that confirms your choice, and an answer output on the right. Once the button is pressed, the input from the list is read and is converted into a corresponding answer. As of right now, all I get is "We recommend... null" after selecting an option in the list. The button appears to do nothing at the moment.
I have used tutorials, hacked up others' code from online, and referenced a few books, but I'm stuck.
Here is what I have:
package diffguidegui;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class DiffGuideGUI extends JPanel implements ListSelectionListener {
private JList resultsTabList;
private DefaultListModel listModel;
private static final String recommendString = "Recommend a Option";
private JButton recommendButton;
private String recommendOutput;
final JLabel output = new JLabel("We recommend..." + recommendOutput);
//build list
public DiffGuideGUI () {
super(new BorderLayout());
listModel = new DefaultListModel();
listModel.addElement("A");
listModel.addElement("B");
//create the list and put it in the scroll pane
resultsTabList = new JList(listModel);
resultsTabList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
resultsTabList.setSelectedIndex(0);
//listener for user input
resultsTabList.addListSelectionListener(this);
resultsTabList.setVisibleRowCount(2);
JScrollPane listScrollPane = new JScrollPane(resultsTabList);
//build the button at the bottom to fire overall behavior
recommendButton = new JButton(recommendString);
recommendButton.setActionCommand(recommendString);
recommendButton.addActionListener(new RecommendListener());
//create a panel that uses Boxlayout for the button
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS));
buttonPane.add(recommendButton);
//create a panel that uses Boxlayout for the label
JPanel outputPane = new JPanel();
outputPane.setLayout(new BoxLayout(outputPane, BoxLayout.LINE_AXIS));
outputPane.add(output);
add(listScrollPane, BorderLayout.WEST);
add(buttonPane, BorderLayout.CENTER);
add(outputPane, BorderLayout.EAST);
}
//build listener class
class RecommendListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//build in logic for choice made here
String resultsTabChoice;
resultsTabChoice = (String)resultsTabList.getSelectedValue();
if( resultsTabChoice.equals("A")) {
recommendOutput = "One";}
else {recommendOutput = "Two";}
}
}
public void valueChanged(ListSelectionEvent e) {
if(e.getValueIsAdjusting() == false) {
if(resultsTabList.getSelectedIndex() == -1) {
recommendButton.setEnabled(false);
} else {
recommendButton.setEnabled(true);
}
}
}
//Create GUI and show it
private static void createAndShowGUI() {
JFrame frame = new JFrame("Recommend Window");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//create and set up content pane
JComponent newContentPane = new DiffGuideGUI();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
//display the window
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
The button appears to do nothing at the moment.
It does something. It calculates the value for your recommendOutput varable. But you never output this value.
try the following:
//build listener class
class RecommendListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//build in logic for choice made here
String resultsTabChoice;
resultsTabChoice = (String)resultsTabList.getSelectedValue();
if( resultsTabChoice.equals("A")) {
recommendOutput = "One";}
else {recommendOutput = "Two";}
System.out.println(recommendOutput); // <-###################
}
}
This should print the value to stdout
To put the value into your label try this instead:
output.setText(recommendOutput);
where do you set the text for the JLabel? It says "We recommend NULL" because recommenedOutput is null when the object is created. I dont see
output.setText("We recommend "+value) anywhere. You probably need output.invalidate() also. Try putting setText(String text)/invalidate() in the RecommendListener.actionPerformed() method.
output.setText("We recommend A");
output.invalidate();
I'm a beginner at java and want to make a JFrame with tabs containing a seperate JPanel. One panel has a list where it displays things that you select in a different panel, so I want this panel to always display a list of stuff that you have selected in a different panel (I hope that makes sense). To do this, I need to make a method to refresh the JList. This is the Farthest that I've gotten on that:
public class PanelClass extends JPanel {
private JList list;
private DefaultListModel listModel = new DefaultListModel();
private ArrayList<SomeOtherClass> objectArray = new ArrayList<SomeOtherClass>();
public PanelClass() {
list.setModel(listModel);
}
public void refresh() {
updateListModel();
list.setModel(listModel);
}
public void updateListModel() {
if (objectArray.isEmpty()) {
System.out.println("No Objects In Array!");
} else {
listModel.clear();
for (SomeOtherClass SOC : objectArray) {
// SOC.getName() just returns a string
listModel.addElement(SOC.getName());
}
}
}
public void addObjectToArray(SomeOtherClass SOC) {
objectArray.add(SOC);
}
}
Could someone please tell me how to make a "refresh" method to constantly keep the JList up to date?
The AWT/Swing event model is based upon the widgets being event sources (in the MVC paradigm, they are both view and controller). Different widgets source different event types.
Look at the java.awt.event (primarily), and javax.swing.event packages for the listener interfaces you'll need to implement and register in order to produce your desired effect.
Basically, you write a Listener implementation, and register it with Widget1. When Widget1 detects an event, it will notify you, and you can then use the information it provides to update Widget2.
For instance, if a button being clicked would add an object to your list, you might have something like below (I usually put this code in the encompassing JFrame class, and make it implement the listener interfaces; but you can choose to use inner classes or separate listener classes):
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyFrame extends JFrame implements ActionListener {
private JButton button = new JButton("Click me!");
private DefaultListModel<String> listModel = new DefaultListModel<String>();
private JList<String> list = new JList<String>(listModel);
private int counter = 1;
public MyFrame() {
setTitle("Test Updates");
JTabbedPane tabs = new JTabbedPane();
add(tabs, BorderLayout.CENTER);
JPanel panel = new JPanel();
panel.add(list);
tabs.add("Selections", panel);
panel = new JPanel();
button.addActionListener(this);
panel.add(button);
tabs.add("Options", panel);
pack();
}
#Override
public void actionPerformed(final ActionEvent event) {
if (button.equals(event.getSource())) {
listModel.addElement("Item " + counter++);
}
}
/* Test it! */
public static void main(String[] args) {
final MyFrame frame = new MyFrame();
frame.addWindowListener(new WindowAdapter() {
#Override public void windowClosing(final WindowEvent e) {
frame.setVisible(false);
frame.dispose();
System.exit(0);
}
});
frame.setVisible(true);
}
}
This code sample is minimal, but it should give you an idea of how to go about implementing what you want.
You can do it in two way. First : Write it in infinite thread loop so that it will constantly update JList. Second : You can call refresh() method whenever new SOC objects are added in your ArrayList. It means you can call refresh() method from addObjectToArray() method which ultimately call the refresh method only when you have some change in your ArrayList.
FYI : I did it in my project and I went for second option.