I have a simple program , that asks for an ip address to connect to , a user id and a password. The IP address is selected through / entered into a combobox.
When the user has entered the address and moved onto another field for entering data , a validation routine is called and in case of an invalid address entered , the combobox background changes to red and a label containing an error message is shown.
The problem is that when the user returns back to the ip combo box , the background color remains red.
it does not change.
How do i code the combobox to overcome my problem ?
Try to use FocusListener on your JComboBox. With it you can manage background color when you enter to combobox and exit from it. Heres simple example:
import java.awt.BorderLayout;
public class Example extends JFrame {
private JComboBox<String> box;
public Example() {
init();
}
private void init() {
box = new JComboBox<String>(getObjects());
box.setBackground(Color.RED);
box.addFocusListener(getFocusListener());
JTextField f = new JTextField();
add(box,BorderLayout.SOUTH);
add(f,BorderLayout.NORTH);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
private FocusListener getFocusListener() {
return new FocusAdapter() {
#Override
public void focusGained(FocusEvent arg0) {
super.focusGained(arg0);
box.setBackground(Color.BLACK);
//validate();
}
#Override
public void focusLost(FocusEvent arg0) {
super.focusLost(arg0);
box.setBackground(Color.red);
//validate();
}
};
}
private String[] getObjects() {
return new String[]{"1","22","33"};
}
public static void main(String... s) {
Example p = new Example();
}
}
Related
I have a table and at each row i have a combox of operator from which we can choose any operator and value1 field value 2 field. COMBO BOX DEFAULT OPERATOR IS " EQUAL TO".so my question is when u click on combobox in any row i should get the value of the selected row and get the operator which i am selecting such that i can perform some operation based on selected operator....
Or else if i change the combobox operator from in between to equal to i should get clear the value 2 field....
Help me get out of this..
You should have an event to know item in the combo is clicked.
Like this:
combo.addActionListener (new ActionListener () {
public void actionPerformed(ActionEvent e) {
//doSomething();
}
});
You have three methods to get current item selected:
Will get the index of the item is order number.
int selectedIndex = myComboBox.getSelectedIndex();
-or-
Will get item selected with Object. You can do many method contains in this Object.
Object selectedObject = myComboBox.getSelectedValue();
-or-
Will get real values of item selected with string type.
String selectedValue = myComboBox.getSelectedValue().toString();
You can see full example code at here (from #secario member):
import java.awt.FlowLayout;
import java.awt.event.*;
import javax.swing.*;
public class MyWind extends JFrame{
public MyWind() {
initialize();
}
private void initialize() {
setSize(300, 300);
setLayout(new FlowLayout(FlowLayout.LEFT));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JTextField field = new JTextField();
field.setSize(200, 50);
field.setText(" ");
JComboBox comboBox = new JComboBox();
comboBox.setEditable(true);
comboBox.addItem("item1");
comboBox.addItem("item2");
//
// Create an ActionListener for the JComboBox component.
//
comboBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
//
// Get the source of the component, which is our combo
// box.
//
JComboBox comboBox = (JComboBox) event.getSource();
Object selected = comboBox.getSelectedItem();
if(selected.toString().equals("item1"))
field.setText("30");
else if(selected.toString().equals("item2"))
field.setText("40");
}
});
getContentPane().add(comboBox);
getContentPane().add(field);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new MyWind().setVisible(true);
}
});
}
}
I have 2 textfields in my project. The first textfield is txtNumA and the second is txtNumB. I disabled txtNumB. When txtNumA is not empty, txtNumB will be enabled.
Well, this is part of code I've tried:
private void txtNumKeyTyped(java.awt.event.KeyEvent evt) {
if(!(txtNumA.getText().trim().equals(""))){
txtNumB.setEnabled(true);
}
else {
txtNumB.setText(null);
txtNumB.setEnabled(false);
}
}
Actually it works, but not perfect. It works only if I typed 2 or more characters in txtNumA. What I need is when I typed one character and more, txtNumB will be enabled.
What's wrong with my code?
What is happening here is,
In case of KeyTyped and KeyPressed events the input is not still given to the TextField.That's why it is not working and works after you type the second character and by that time first character must have reached the TextField.So use KeyReleased method to handle this case.
t is the first TextField and t1 is second.
t.addKeyListener(new KeyListener(){
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
JTextField bt = (JTextField)e.getSource();
if(bt.getText().trim().length()>0){
t1.setEnabled(true);
}
else
t1.setEnabled(false);
}
});
The correct way is to add a DocumentListener to the Document of your JTextField:
public final class TextFieldListener implements DocumentListener {
public static void main(final String... args) {
SwingUtilities.invokeLater(() -> new TextFieldListener().go());
}
private final JFrame frame = new JFrame();
private final JTextField field = new JTextField();
private final JTextField field2 = new JTextField();
private TextFieldListener() {
field.getDocument().addDocumentListener(this);
frame.setLayout(new GridLayout(2, 0));
frame.add(field);
frame.add(field2);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
onFieldUpdated();
}
private void go() {
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void onFieldUpdated() {
setField2Enabled(!field.getText().isEmpty());
}
private void setField2Enabled(final boolean enabled) {
field2.setEnabled(enabled);
}
#Override
public void insertUpdate(final DocumentEvent e) {
onFieldUpdated();
}
#Override
public void removeUpdate(final DocumentEvent e) {
onFieldUpdated();
}
#Override
public void changedUpdate(final DocumentEvent e) {}
}
It is not correct to add a KeyListener to your text field if you are interested in changes to its content.
Further reading:
JTextComponent
Document
Text Component Features
How to Use Text Fields
How to Write a Document Listener
I think the problem with this working for 2 characters is because getText() method returns not updated value, i.e. it returns the value BEFORE the change. What you need to do is somehow update that value before you compare it to empty string.
You may need to investigate KeyEvent to see if user adds another character or is it e.g. backspace...
I am using lwuit to create a table with some values and a row listener. in j2me.
I am trying to add a button and a listener to it so that i have a value in the table by which i can implement a row listener. I have used the following link: http://lwuit.blogspot.in/2010/06/headon-that-table.html. But when i add the button to the table it comes to the end of the table because the table model only accepts the object as its input that is added to the table.
By using this link i added the button by the button by the following command:
container.addComponent(new Button("Details"));
Also i tried to create a grid layout or a table layout and added buttons with the number rows*columns but still the listener for the last button works, not for the rest. Any ideas on how can implement this logic. My actual task is to add a row click listener to the table. Any conceptual or coding help is appreciated.
Mean while i got the answer for a friend which i am sharing with you. He said me to add buttons in grid or table layout and the buttons should be adding like a 2d array so that their listeners are properly managed.
public class Midlet extends MIDlet implements ActionListener{
Form f;
Container c;
private int ROWS=100;
Button b[][];
private int COLUMNS=3;
public void startApp() {
Display.init(this);
f=new Form("grid with buttons");
c=new Container(new TableLayout(ROWS, COLUMNS));
b=new Button[ROWS][COLUMNS];
c.setScrollableX(true);
c.setScrollableY(true);
//c.setDraggable(true);
addElements();
//f.setScrollable(false);
f.setScrollVisible(true);
f.addComponent(c);
f.show();
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
public void addElements()
{
for(int i=0;i<ROWS;i++)
{
for(int j=0;j<COLUMNS;j++)
{
b[i][j]=new Button(i+" sdkljf "+j);
c.addComponent(b[i][j]);
b[i][j].addActionListener(this);
}
}
}
/**
*
* #param message message to be displayed
* #param title title of the alert
*/
public void showMsg(String message, String title)
{
final Dialog d=new Dialog(title);
d.setLayout(new GridLayout(1, 1));
Button b=new Button("Ok");
TextArea msg=new TextArea(message);
msg.setUIID(message);
msg.setEditable(false);
//dialogContainer.addComponent(msg);
//dialogContainer.addComponent(b);
d.addComponent(msg);
d.addComponent(b);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
d.dispose();
}
});
d.show();
}
public void actionPerformed(ActionEvent evt) {
for(int i=0;i<ROWS;i++)
{
for(int j=0;j<COLUMNS;j++)
{
if(b[i][j]==evt.getComponent())
{
showMsg(i+","+j, "sl;dkf;");
}
}
}
}
}
I made a button and did a .setText() on it because I have to compare the value of the .setText() with something else.
I applied the .setText() to a JButton, but I don't want the text to be visible in my button.
If I do setVisible(false) then it hides the whole button, but I only want it to hide the text.
Is there an option for this? I've considered making a custom font and apply it on the text in the .setText() but I'm wondering if there's a more efficient option to my problem.
Thanks in advance guys.
EDIT: I can't use .setText(" ") because I have to compare the value within it.
You state:
EDIT: I can't use .setText(" ") because I have to compare the value within it.
Nonsense. As I've mentioned in a comment, set the JButton's text to " ", and don't use the JButton's text for comparison. Instead use its actionCommand easily obtained via getActionCommand(). Or use a HashMap<JButton, SomethingElse>.
You may consider changing the JButton's Action when you need to change its behavior and state which is easily done by calling setAction(...)
For example,
import java.awt.event.ActionEvent;
import javax.swing.*;
public class ButtonActions {
private static void createAndShowGui() {
JPanel mainPanel = new JPanel();
JButton myButton = new JButton();
StartAction startAction = new StartAction();
PauseAction pauseAction = new PauseAction();
BlankAction blankAction = new BlankAction();
startAction.setNextAction(pauseAction);
pauseAction.setNextAction(blankAction);
blankAction.setNextAction(startAction);
myButton.setAction(startAction);
mainPanel.add(myButton);
JFrame frame = new JFrame("ButtonActions");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class SwappingAction extends AbstractAction {
private Action nextAction;
public SwappingAction(String text) {
super(text);
}
public void setNextAction(Action nextAction) {
this.nextAction = nextAction;
}
public Action getNextAction() {
return nextAction;
}
#Override
/**
* super method needs to be called in child for swap to work
*/
public void actionPerformed(ActionEvent e) {
System.out.println("ActionCommand: " + e.getActionCommand());
((AbstractButton)e.getSource()).setAction(nextAction);
}
}
class StartAction extends SwappingAction {
public static final String START = "Start";
public StartAction() {
super(START);
}
#Override
public void actionPerformed(ActionEvent e) {
super.actionPerformed(e);
// start-specific code goes here
}
}
class PauseAction extends SwappingAction {
public static final String PAUSE = "Pause";
public PauseAction() {
super(PAUSE);
}
#Override
public void actionPerformed(ActionEvent e) {
super.actionPerformed(e);
// pause-specific code goes here
}
}
class BlankAction extends SwappingAction {
public static final String BLANK = " ";
public BlankAction() {
super(BLANK);
}
#Override
public void actionPerformed(ActionEvent e) {
super.actionPerformed(e);
}
}
Write buttonName.setText(" ") this will not display any name to the button. And whenever you feel like displaying the name (on any event) then set it again buttonName.setText("some text")
If you insist not to use setText(""), try setting same colour as a background colour and text colour. Check the below links
setBackground(java.awt.Color)
setForeground(java.awt.Color)
Why don't you name the first button " " (1 space).
the second: " " (2 spaces)
the third: " "(3 spaces) and so on ..
Now, compare:
if((event.getActionCommand()).equals(" "))
{ //1st button }
if((event.getActionCommand()).equals(" "))
{ //2nd button }
..and so on
where event is an object of ActionEvent
This way the buttons will have a unique names and be invisible.
Horrible coding, I know. But it does the trick ;)
Instead of .setText(), use .setTag() and .getTag() to attach some value to a View - including a Button - for later retrieval.
These methods are there directly for that kind of purpose.
I have made a multiple input dialog by building a JPanel with the fields I want and adding it to a JOption pane
JMainPanel mainPanel = new JMainPanel(mensaje, parametros, mgr);
int i = JOptionPane.showOptionDialog(null, mainPanel, "Sirena",
JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null,
new String[] {"Aceptar", "Cancelar"}, "Aceptar");
However I'm having trouble with the buttons, because some of the fields are required. How can I make the "Ok" button to be enabled once every required field is up, or making the click on the button to make the validations and do not close the pane until every required field is filled?
From the Java API, I found this:
options - an array of objects indicating the possible choices the user
can make; if the objects are components, they are rendered properly;
non-String objects are rendered using their toString methods; if this
parameter is null, the options are determined by the Look and Feel
So, can't I pass custom buttons as parameter?
Looks like I will have to make my own JDialog? for which case, I don't know how to make it return an int just like JOptionPane does, any recommended tutorial?
In the example options is {"Aceptar", "Cancelar"} which are the displayed buttons,
PS. I have full controll over the fields I added to the JPanel.
This is a screenshot of the JOptionPane:
I don't think that you can de-activate a JOptionPane's selections buttons, but one way to still use the JOptionPane is to simply re-display it if the required fields have not been set. You could display an error message JOptionPane first describing the error, and then display a new JOptionPane that holds the same JPanel as its second parameter -- so that the data already entered has not been lost. Otherwise, you may want to create your own JDialog which by the way isn't that hard to do.
Edit
I'm wrong. You can enable and disable the dialog buttons if you use a little recursion.
For example:
import java.awt.Component;
import java.awt.Container;
import java.awt.event.*;
import java.util.HashSet;
import java.util.Set;
import javax.swing.*;
public class Foo extends JPanel {
private static final String[] DIALOG_BUTTON_TITLES = new String[] { "Aceptar", "Cancelar" };
private JCheckBox checkBox = new JCheckBox("Buttons Enabled", true);
private Set<AbstractButton> exemptButtons = new HashSet<AbstractButton>();
public Foo() {
JButton exemptBtn = new JButton("Exempt Button");
JButton nonExemptBtn = new JButton("Non-Exempt Button");
add(checkBox);
add(exemptBtn);
add(nonExemptBtn);
exemptButtons.add(checkBox);
exemptButtons.add(exemptBtn);
checkBox.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
allBtnsSetEnabled(checkBox.isSelected());
}
});
}
private void allBtnsSetEnabled(boolean enabled) {
JRootPane rootPane = SwingUtilities.getRootPane(checkBox);
if (rootPane != null) {
Container container = rootPane.getContentPane();
recursiveBtnEnable(enabled, container);
}
}
private void recursiveBtnEnable(boolean enabled, Container container) {
Component[] components = container.getComponents();
for (Component component : components) {
if (component instanceof AbstractButton && !exemptButtons.contains(component)) {
((AbstractButton) component).setEnabled(enabled);
} else if (component instanceof Container) {
recursiveBtnEnable(enabled, (Container) component);
}
}
}
public int showDialog() {
return JOptionPane.showOptionDialog(null, this, "Sirena",
JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null,
DIALOG_BUTTON_TITLES, "Aceptar");
}
private static void createAndShowGui() {
Foo foo = new Foo();
int result = foo.showDialog();
System.out.println(DIALOG_BUTTON_TITLES[result]);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
This code uses listeners to check the state of a JCheckBox, but you can have listeners (DocumentListeners) listening to text field documents if you desire to know if they have data or not. The code then gets the JRootPane that holds the JCheckBox, then the root pane's contentPane, and all components of the dialog are held by this. It then recurses through all the components held by the dialog. If a component is a Container, it recurses through that container. If the component is an AbstractButton (such any JButton or checkbox), it enables or disables -- except for buttons held in the exempt buttons set.
A better example with document listeners
import java.awt.*;
import java.awt.event.*;
import java.util.HashSet;
import java.util.Set;
import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
public class Foo2 extends JPanel {
private static final String[] DIALOG_BUTTON_TITLES = new String[] {
"Aceptar", "Cancelar" };
private static final int FIELD_COUNT = 10;
private Set<AbstractButton> exemptButtons = new HashSet<AbstractButton>();
private JTextField[] fields = new JTextField[FIELD_COUNT];
public Foo2() {
setLayout(new GridLayout(0, 5, 5, 5));
DocumentListener myDocListener = new MyDocumentListener();
for (int i = 0; i < fields.length; i++) {
fields[i] = new JTextField(10);
add(fields[i]);
fields[i].getDocument().addDocumentListener(myDocListener);
}
// cheating here
int timerDelay = 200;
Timer timer = new Timer(timerDelay , new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
checkDocsForText();
}
});
timer.setRepeats(false);
timer.setInitialDelay(timerDelay);
timer.start();
}
private void checkDocsForText() {
for (JTextField field : fields) {
if (field.getText().trim().isEmpty()) {
allBtnsSetEnabled(false);
return;
}
}
allBtnsSetEnabled(true);
}
private void allBtnsSetEnabled(boolean enabled) {
JRootPane rootPane = SwingUtilities.getRootPane(this);
if (rootPane != null) {
Container container = rootPane.getContentPane();
recursiveBtnEnable(enabled, container);
}
}
private void recursiveBtnEnable(boolean enabled, Container container) {
Component[] components = container.getComponents();
for (Component component : components) {
if (component instanceof AbstractButton && !exemptButtons.contains(component)) {
((AbstractButton) component).setEnabled(enabled);
} else if (component instanceof Container) {
recursiveBtnEnable(enabled, (Container) component);
}
}
}
public int showDialog() {
return JOptionPane.showOptionDialog(null, this, "Sirena",
JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null,
DIALOG_BUTTON_TITLES, "Aceptar");
}
private class MyDocumentListener implements DocumentListener {
public void removeUpdate(DocumentEvent arg0) {
checkDocsForText();
}
public void insertUpdate(DocumentEvent arg0) {
checkDocsForText();
}
public void changedUpdate(DocumentEvent arg0) {
checkDocsForText();
}
}
private static void createAndShowGui() {
Foo2 foo = new Foo2();
int result = foo.showDialog();
if (result >= 0) {
System.out.println(DIALOG_BUTTON_TITLES[result]);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
I suggest you to define some properties into your JPanel extended class, and use PropertyChangeListener to listen the occured changes and enable/disable relative buttons.
Here's an article.
Another issue maybe finding the ok/cancel buttons in the hierarchy of components, since the JDialog is created through JOptionPane and you haven't a reference to the buttons. Here's a useful thread .
You can add a property to a JComponent using putClientProperty method.
When changes occurs to a given property a PropertyChanged event is raised.
So in your example you can define a boolean property indicating that required that are inserted into the JDialog. Then add a PropertyChangeListener that when is notified enable/disable the ok button.