Develop Reference

Adding and removing checkboxes dynamically

I want to make ToDoList App. After successfully adding task to do (which contains checkbox, JLabel and date, all putted in a box) i want to remove them dynamically. With adding it's not problem but when i try to remove (ater clicking checked in checkbox) it works only once. Then it either removes not once which are intended or not removing them at all. I am not sure why it's not working so I paste all code below.
JSpinner dateSpin;
Box eventBox, boxBox;
Box[] taskBox = new Box[1000];
JTextField eventName;
Date date;
Checkbox[] doneCheck = new Checkbox[1000];
JLabel taskLabel;
JPanel panel;
JScrollPane scrollPane;
SimpleDateFormat simpleDate;
int i = 0;
public static void main(String[] args) {
new Main();
}
private Main(){
this.setSize(400, 600);
this.setTitle("To-Do List");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(false);
this.setLocationRelativeTo(null);
panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
boxBox = Box.createVerticalBox();
scrollPane = new JScrollPane(panel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
eventBox = Box.createHorizontalBox();
eventBox.setBorder(BorderFactory.createEtchedBorder());
JLabel plusSign = new JLabel("+");
plusSign.setFont(new Font("Serafi", PLAIN, 20));
plusSign.setMaximumSize(new Dimension(Integer.MAX_VALUE, plusSign.getMinimumSize().height));
eventBox.add(plusSign);
eventName = new JTextField(20);
eventName.setFont(new Font("Times", Font.ITALIC, 15));
eventName.setMaximumSize(new Dimension(Integer.MAX_VALUE, eventName.getMinimumSize().height));
eventName.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == eventName){
/* to do: saving every task in some file, figure out how to remove
those tasks (checkbox + jlabel) -> whole box from screen or how to send them to "done"
also "done" to do*/
simpleDate = new SimpleDateFormat("E-dd-MM-yyyy");
taskBox[i] = Box.createHorizontalBox();
taskBox[i].setBorder(BorderFactory.createTitledBorder(simpleDate.format(date)));
doneCheck[i] = new Checkbox();
doneCheck[i].addItemListener(new ItemListener() {
#Override
public void itemStateChanged(ItemEvent e) {
int k = 0;
for (int j = 0; j < doneCheck.length; j++) {
if(doneCheck[j].getState()){
//remove(doneCheck[k]);
//System.out.println("?" + i + "?" + k + " " + e.getSource().toString());
System.out.println("xxxxx" + doneCheck[j].getState());
break;
}
System.out.println("oooooo");
k++;
}
System.out.println(doneCheck.length + taskBox[k].toString());
//System.out.println("! " + k + " " + e.getSource().toString());
boxBox.remove(taskBox[k]);
//boxBox.removeAll();
boxBox.revalidate();
boxBox.repaint();
}
});
taskBox[i].add(doneCheck[i]);
String taskName = eventName.getText();
taskLabel = new JLabel(taskName);
taskLabel.setMinimumSize(new Dimension(500,10));
taskLabel.setPreferredSize(new Dimension(300, 10));
taskBox[i].add(taskLabel);
boxBox.add(taskBox[i]);
boxBox.setMaximumSize(new Dimension(Integer.MAX_VALUE, boxBox.getMinimumSize().height + 11));
panel.add(boxBox);
panel.revalidate();
panel.repaint();
i++;
}
}
});
eventBox.add(eventName);
date = new Date();
dateSpin = new JSpinner(new SpinnerDateModel(date, null, null, Calendar.DAY_OF_MONTH));
JSpinner.DateEditor dateEditor = new JSpinner.DateEditor(dateSpin, "dd/MM/yy");
dateSpin.setEditor(dateEditor);
dateSpin.setMaximumSize(new Dimension(Integer.MAX_VALUE, dateSpin.getMinimumSize().height));
dateSpin.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
if(e.getSource() == dateSpin){
date = (Date) dateSpin.getValue();
}
}
});
eventBox.add(dateSpin);
panel.add(eventBox, new FlowLayout());
this.add(scrollPane);
this.setVisible(true);
}

You never remove elements from the taskBox and doneCheck arrays.
Now if you mark the first entry as done, your ItemListener will always find this first entry when looping over the doneCheck array.
Marking the entries as done in reverse order (always the last shown entry) will remove one entry after the other.
As to your software design: it's considered bad practice to manage your data in several parallel arrays.
Please consider creating a custom class for the todo items that manages all the elements of a single todo item.

Unless you are initializing doneCheck items somewhere, this:
Checkbox[] doneCheck = new Checkbox[1000];
And this:
int k = 0;
for (int j = 0; j < doneCheck.length; j++) {
if (doneCheck[j].getState()) {
--------^^^^^^^^^^^^
Is probably one the reason it fails: you probably got a NullPointerException somewhere, eg: when value of j > 0. The NPE will probably be catched by the EventDispatchThread which may or may not be kind enough to show it on stderr...
I fail to see why you are using this array, and you can shorten your code and avoid NPE like this:
Checkbox cb = new Checkbox();
cb.addItemListener(event -> {
if (cb.getState()) { // not null!
boxBox.remove(cb);
boxBox.revalidate();
boxBox.repaint();
}
});
doneCheck[i] = cb; // I still don't know why you need that.

My guess is that you have 2 variables global int i = 0 and local int k = 0 in here
public void itemStateChanged(ItemEvent e) {
// int k = 0;//<-------- LOCAL
for (int j = 0; j < doneCheck.length; j++) {
if(doneCheck[j].getState()){
//Either k = j;
boxBox.remove(taskBox[j]);
//remove(doneCheck[k]);
//System.out.println("?" + i + "?" + k + " " + e.getSource().toString());
System.out.println("xxxxx" + doneCheck[j].getState());
break;
}
System.out.println("oooooo");
//k++;//<-- ALWAYS == last j value before the break;
}
System.out.println(doneCheck.length + taskBox[k].toString());
//System.out.println("! " + k + " " + e.getSource().toString());
//boxBox.remove(taskBox[k]);//
//boxBox.removeAll();
boxBox.revalidate();
boxBox.repaint();
}
Every time you call for itemStateChanged int k = 0; will be initialized to 0 and you will be removing element[j] from array of taskBox. As you k++ statement will be equal to the last j value before the break; because it sits after the if(doneCheck[j].getState()){...
Try moving boxBox.remove(taskBox[j]); inside the for loop and using j instead of k.

Program freezing(not responding) after button click no a Java app

Ok so I'm building to show students how a loop goes through an array, I have added 2 images to help explain and the code, the first is the result I get after I click go then it freezes . The Second image is what I'd like it to do after you put in the values of 1 in start, 15 in stop, 3 in step and click the Go Button. And then to be cleared on the click of Clear button. I think they probably related. Can anyone see the problem? Thanks in advanced!
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
import javax.swing.JOptionPane;
public class Checkerboard extends Frame implements ActionListener
{
int[] blocksTextField = new int[15];
Panel blocksPanel = new Panel();
TextArea blocksDisplay[] = new TextArea[16];
TextField start = new TextField (3);
TextField stop = new TextField (3);
TextField step = new TextField (3);
//Colors
Color Red = new Color(255, 90, 90);
Color Green = new Color(140, 215, 40);
Color white = new Color(255,255,255);
//textField ints
int inputStart;
int inputStop;
int inputStep;
//Lables
Label custStartLabel = new Label ("Start : ");
Label custStopLabel = new Label ("Stop : ");
Label custStepLabel = new Label ("Step : ");
//Buttons
Button goButton = new Button("Go");
Button clearButton = new Button("Clear");
//panel for input textFields and lables
Panel textInputPanel = new Panel();
//Panel for buttons
Panel buttonPanel = new Panel();
public Checkerboard()
{//constructor method
//set the 3 input textFields to 0
inputStart = 0;
inputStop = 0;
inputStep = 0;
//set Layouts for frame and three panels
this.setLayout(new BorderLayout());
//grid layout (row,col,horgap,vertgap)
blocksPanel.setLayout(new GridLayout(4,4,10,10));
textInputPanel.setLayout(new GridLayout(2,3,20,10));
buttonPanel.setLayout(new FlowLayout());
//setEditable()
//setText()
//add components to blocks panel
for (int i = 0; i<16; i++)
{
blocksDisplay[i] = new TextArea(null,3,5,3);
if(i<6)
blocksDisplay[i].setText(" " +i);
else
blocksDisplay[i].setText(" " +i);
blocksDisplay[i].setEditable(false);
// blocksDisplay[i].setBackground(Red);
blocksPanel.add(blocksDisplay[i]);
}//end for
//add componets to panels
//add text fields
textInputPanel.add(start);
textInputPanel.add(stop);
textInputPanel.add(step);
//add lables
textInputPanel.add(custStartLabel);
textInputPanel.add(custStopLabel);
textInputPanel.add(custStepLabel);
//add button to panel
buttonPanel.add(goButton);
buttonPanel.add(clearButton);
//ADD ACTION LISTENRS TO BUTTONS (!IMPORTANT)
goButton.addActionListener(this);
clearButton.addActionListener(this);
add(blocksPanel, BorderLayout.NORTH);
add(textInputPanel, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
//overridding the windowcClosing() method will allow the user to clisk the Close button
addWindowListener(
new WindowAdapter()
{
public void windowCloseing(WindowEvent e)
{
System.exit(0);
}
}
);
}//end of constructor method
public void actionPerformed(ActionEvent e)
{
//if & else if to see what button clicked and pull user input
if(e.getSource() == goButton) //if go clicked ...
{
System.out.println("go clicked");
try{
String inputStart = start.getText();
int varStart = Integer.parseInt(inputStart);
if (varStart<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("start = " + varStart);
// roomDisplay[available].setBackground(lightRed);
String inputStop = stop.getText();
int varStop = Integer.parseInt(inputStop);
if (varStop<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("stop = " + varStop);
String inputStep = step.getText();
int varStep = Integer.parseInt(inputStep);
if (varStep<=0 || varStep>=15 )throw new NumberFormatException();
System.out.println("step = " + varStep);
for (int i = varStart; i<varStop; varStep++)//ADD WHILE LOOP
{
blocksDisplay[i].setBackground(Red);
blocksDisplay[i].setText(" " +i);
}
}
catch (NumberFormatException ex)
{
JOptionPane.showMessageDialog(null, "You must enter a Start, Stop and Step value greater than 0 and less than 15",
"Error",JOptionPane.ERROR_MESSAGE);
}
}
else if(e.getSource() == clearButton ) //else if clear clicked ...
{
System.out.println("clear clicked");
}
//int available = room.bookRoom(smoking.getState());
//if (available > 0)//Rooms is available
}//end action performed method
public static void main(String[]args)
{
Checkerboard frame = new Checkerboard ();
frame.setBounds(50, 100, 300, 410);//changed size to make text feilds full charater size
frame.setTitle("Checkerboarder Array");
frame.setVisible(true);
}//end of main method
}

The problem is your loop: your loop variable name is i but you change the varStep variable instead of i so basically the loop variable never changes and thus the exit condition will never be true.
I believe you want to step i with varStep, so change your loop to:
for (int i = varStart; i<varStop; i += varStep)
// stuff inside loop

Take a look at this loop.
for (int i = varStart; i<varStop; varStep++)//ADD WHILE LOOP
{
blocksDisplay[i].setBackground(Red);
blocksDisplay[i].setText(" " +i);
}
It ends when i >= varStop, but neither i nor varStop change as a consequence of its execution, so it can never stop. You only increment varStep.
I think you want to increment i by varStep on each iteration instead, i.e. i += varStep

You use varStep++ in your for loop. I think you meant to do i+varStep.
The application freezes because you're never increasing i, resulting in an endless loop.

How to identify ID of Labels in Java

I have created 9 JLabels by array. And it has common Event Listener with method of mouseClicked(MouseEvent src){... }, here i am finding problem is, how can I identify which JLabel is clicked?
Say, if label[0] is clicked then I want to show "Label-0 is clicked",
if label[1] is clicked then I want to show "Label-1 is clicked"
Can I perform this? if yes then How?
NOTE :- I found some answer stating that add Custom 'id' Property, I would but first, I prefer if there is any default method exist.

Add Label
JPanel pnl = new JPanel(new FlowLayout());
dd.add(pnl);
addlistener();
for (int i = 0; i < 10; i++) {
pnl.add(lbl[i] = new JLabel("" + i));
lbl[i].addMouseListener(listern);
}
Listener
public void mouseEnter(MouseEvent me) {
System.err.println("Hi");
me.getComponent();
if(me.getSource() instanceof JLabel){
System.out.println("lable"+ ((JLabel)me.getSource()).getText());
}
}

You could loop the array comparing the source of the event to each element in the array...
for (int index = 0; index < myLabelArray.length; index++) {
if (myLabelArray[index].equals(src.getSource())) {
System.out.println("Label-" + index + " was clicked");
break;
}
}
Or you could "name" each label...
JLabel[] myLabelArray = new JLabel[9];
for (int index = 0; index < 9; index++) {
JLabel label = new JLabel("...");
label.setName(Integer.toString(index));
label.addMouseListener(commonMouseListener);
myLabelArray[index] = label;
}
Then in your mouse listener...
public void mouseClicked(MouseEvent evt) {
System.out.println("Label-" + ((JLabel)evt.getSource()).getName() + " was clicked");
}
Or you could use a Map instead of an array or a List...

Accessing locally defined JButtons in a GridLayout JPanel

Lets say you have a GridLayout of JButtons in an NxN grid, in code such as this:
JPanel bPanel = new JPanel();
bPanel.setLayout(new GridLayout(N, N, 10, 10));
for (int row = 0; row < N; row++)
{
for (int col = 0; col < N; col++)
{
JButton b = new JButton("(" + row + ", " + col + ")");
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
}
});
bPanel.add(b);
}
}
How would one access each button individually in the grid to change the button's name through setText()? This needs to be done outside of actually pressing the button in question.
Because each button in instantiated locally as "b", a globally accessible name for each button is not possible at current. What could be done to access each button independently? Could an array like JButton[][] hold references to all the buttons? How can this be set up in the code above?
Any input is appreciated.
Thanks.

you can,
1) putClientProperty
buttons[i][j].putClientProperty("column", i);
buttons[i][j].putClientProperty("row", j);
buttons[i][j].addActionListener(new MyActionListener());
and
public class MyActionListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
JButton btn = (JButton) e.getSource();
System.out.println("clicked column " + btn.getClientProperty("column")
+ ", row " + btn.getClientProperty("row"));
}
2) ActionCommand

You can create an array (or list or something else) to store all the buttons. Or you can use public Component[] getComponents() method of the bPanel (Container).

How can I determine which JCheckBox caused an event when the JCheckBox text is the same

I am working on a program that needs to determine which JCheckBox was selected. I am using three different button groups, two of which have overlapping text. I need to be able to determine which triggered the event so I can add the appropriate charge (COSTPERROOM vs COSTPERCAR) to the total(costOfHome). What I cant figure out is how to differentiate the checkbox source if the text is the same. I was thinking of trying to change the text on one button group to strings like "one" "two" etc, but that introduces a bigger problem with how I have created the checkboxes in the first place. Any ideas would be appreciated, thanks in advance!
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JMyNewHome extends JFrame implements ItemListener {
// class private variables
private int costOfHome = 0;
// class arrays
private String[] homeNamesArray = {"Aspen", "Brittany", "Colonial", "Dartmour"};
private int[] homeCostArray = {100000, 120000, 180000, 250000};
// class constants
private final int MAXROOMS = 3;
private final int MAXCARS = 4;
private final int COSTPERROOM = 10500;
private final int COSTPERCAR = 7775;
JLabel costLabel = new JLabel();
// constructor
public JMyNewHome ()
{
super("My New Home");
setSize(450,150);
setLayout(new FlowLayout());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Font labelFont = new Font("Time New Roman", Font.BOLD, 24);
setJLabelString(costLabel, costOfHome);
costLabel.setFont(labelFont);
add(costLabel);
JCheckBox[] homesCheckBoxes = new JCheckBox[homeNamesArray.length];
ButtonGroup homeSelection = new ButtonGroup();
for (int i = 0; i < homeNamesArray.length; i++)
{
homesCheckBoxes[i] = new JCheckBox(homeNamesArray[i], false);
homeSelection.add(homesCheckBoxes[i]);
homesCheckBoxes[i].addItemListener(this);
add(homesCheckBoxes[i]);
}
JLabel roomLabel = new JLabel("Number of Rooms in Home");
add(roomLabel);
ButtonGroup roomSelection = new ButtonGroup();
JCheckBox[] roomCheckBoxes = new JCheckBox[MAXROOMS];
for (int i = 0; i < MAXROOMS; i++)
{
String intToString = Integer.toString(i + 2);
roomCheckBoxes[i] = new JCheckBox(intToString);
roomSelection.add(roomCheckBoxes[i]);
roomCheckBoxes[i].addItemListener(this);
add(roomCheckBoxes[i]);
}
JLabel carLabel = new JLabel("Size of Garage (number of cars)");
add(carLabel);
ButtonGroup carSelection = new ButtonGroup();
JCheckBox[] carCheckBoxes = new JCheckBox[MAXCARS];
for (int i = 0; i < MAXCARS; i++)
{
String intToString = Integer.toString(i);
carCheckBoxes[i] = new JCheckBox(intToString);
carSelection.add(carCheckBoxes[i]);
carCheckBoxes[i].addItemListener(this);
add(carCheckBoxes[i]);
}
setVisible(true);
}
private void setJLabelString(JLabel label, int cost)
{
String costOfHomeString = Integer.toString(cost);
label.setText("Cost of Configured Home: $ " + costOfHomeString + ".00");
invalidate();
validate();
repaint();
}
public void itemStateChanged(ItemEvent e) {
JCheckBox source = (JCheckBox) e.getItem();
String sourceText = source.getText();
//JLabel testLabel = new JLabel(sourceText);
//add(testLabel);
//invalidate();
//validate();
//repaint();
for (int i = 0; i < homeNamesArray.length; i++)
{
if (sourceText == homeNamesArray[i])
{
setJLabelString(costLabel, costOfHome + homeCostArray[i]);
}
}
}
}

I would
Use JRadioButtons for this rather than JCheckBoxes since I think it is GUI standard to have a set of JRadioButtons that only allow one selection rather than a set of JCheckBoxes.
Although you may have "overlapping text" you can set the button's actionCommand to anything you want to. So one set of buttons could have actionCommands that are "room count 2", "room count 3", ...
But even better, the ButtonGroup can tell you which toggle button (either check box or radio button) has been selected since if you call getSelection() on it, it will get you the ButtonModel of the selected button (or null if none have been selected), and then you can get the actionCommand from the model via its getActionCommand() method. Just first check that the model selected isn't null.
Learn to use the layout managers as they can make your job much easier.
For instance, if you had two ButtonGroups:
ButtonGroup fooBtnGroup = new ButtonGroup();
ButtonGroup barBtnGroup = new ButtonGroup();
If you add a bunch of JRadioButtons to these ButtonGroups, you can then check which buttons were selected for which group like so (the following code is in a JButton's ActionListener):
ButtonModel fooModel = fooBtnGroup.getSelection();
String fooSelection = fooModel == null ? "No foo selected" : fooModel.getActionCommand();
ButtonModel barModel = barBtnGroup.getSelection();
String barSelection = barModel == null ? "No bar selected" : barModel.getActionCommand();
System.out.println("Foo selected: " + fooSelection);
System.out.println("Bar selected: " + barSelection);
Assuming of course that you've set the actionCommand for your buttons.

Checkboxes have item listeners like any other swing component. I would decouple them, and simply add listeners to each
{
checkBox.addActionListener(actionListener);
}
http://www.java2s.com/Code/Java/Swing-JFC/CheckBoxItemListener.htm