Develop Reference

How do I make a selected Combobox value display different text?

I am new to Java and couldn't find any answers for my problem that I was able to understand.
I want to make a selected value in my ComboBox change what text is displayed in the textfield.
For example, if the user selects an artist in the combobox, then the artists' albums are displayed in the textfield.
Any help is appreciated. Thanks!
private void jComboBox1ActionPerformed(java.awt.event.ActionEvent evt) {
String a = (String)jComboBox1.getSelectedItem();
int artists = 0;
switch (artists){
case 0: jTextField1.setText("Take Care, Nothing Was The Same, Views, More Life, Scorpion");
break;
case 1: jTextField1.setText("Stoney, Beerbongs & Bentleys");
break;
case 2: jTextField1.setText("One Love, Listen, Nothing But the Beat");
break;
case 3: jTextField1.setText("Ready for the Weekend, 18 Months, Motion");
break;
case 4: jTextField1.setText("Cole World: The Sideline Story, 2014 Forest Hills Drive, 4 Your Eyez Only");
break;
case 5: jTextField1.setText("My Beautiful Dark Twisted Fantasy, Yeezus, The Life of Pablo, ye");
break;
case 6: jTextField1.setText("Parachutes, a Rush of Blood to the Head, X&Y, Viva La Vida, Mylo Xyloto");
}
}

Here is a full working example:
import java.awt.GridLayout;
import javax.swing.*;
public class ChangeTextViaCheckbox extends JFrame {
public ChangeTextViaCheckbox() {
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(new GridLayout(3, 1));
JCheckBox cb1 = new JCheckBox("Checkbox 1");
JCheckBox cb2 = new JCheckBox("Checkbox 2");
JTextField tf = new JTextField();
cb1.addActionListener(e -> tf.setText("CB 1 is active"));
cb2.addActionListener(e -> tf.setText("CB 2 is active"));
add(cb1);
add(cb2);
add(tf);
}
public static void main(String[] args) {
ChangeTextViaCheckbox frame = new ChangeTextViaCheckbox();
frame.pack();
}
}
The both ActionListener listen on a performed action. If thats the case, they set a new Text in the JTextField.
But it would be better, if you implement it via JRadioButton and a ButtonGroup. With this there can't be a multiple choice.

Your question is lacking details and examples, you should post the important parts of your code that you've already written, for example I have no idea now what [GUI] API are you using(for example swing or AWT), so I strongly advise you to edit your question and provide more details, but either way I'm going to give you a simple example.
I'm going to assume your using the swing api, but it shouldn't be that different if your using another GUI api (like AWT).
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class SwingExample extends JFrame{
public SwingExample(){
String[] artists = {"artist1","artist2","artist3"};
Map<String,String> albumOfArtists = new HashMap<String,String>();
albumOfArtists.put("artist1","album1");
albumOfArtists.put("artist2","album2");
albumOfArtists.put("artist3","album3");
JComboBox combo1 = new JComboBox<String>(artists);
JTextField field1 = new JTextField();
//You implement an action listener to define what should be done when
//an user performs certain operation. An action event occurs,
//whenever an action is performed by the user. Examples: When the user
//clicks a button, chooses a menu item, presses Enter in a text field.
//add action listener to your combobox:
combo1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
String selectedString=(String)combo1.getSelectedItem();
field1.setText(albumOfArtists.get(selectedString));
//for example if you select artist1 then the text displayed in the text field is: album1
}
}
add(combo1);
add(field1);
}
private static void createAndShowGUI() {
JFrame frame = new CreateNewJTextField();
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
createAndShowGUI();
}
}

You can use switch() for your combobox. I've written a code which has the name defined to combobox as cb1. The getSelectedItem() method is used for cb1. You can define the corresponding command for each case (starting from index 0).
String a = (String)cb1.getSelectedItem();
int i = 0;
switch (i){
case 0:
break;
}
Make sure to end each case with break; or your code will execute repeatedly.
Now if the textfield you're using is t1 then the following code is generalised,
switch (i) {
case 0: t1.setText(<whatever you want to display>);
break;
}
Hope this helps.
Here's the revisited code:
String a = (String)cb1.getSelectedItem();
int i = 0;
switch(i){
case 0: t1.setText("Take Care, Nothing Was The Same, Views, More Life, Scorpion");
// for combobox option Drake index = 0
break;
case 1: t1.setText("Stoney, Beerbongs & Bentleys");
// for combobox option post_malone index = 1
break;
case 2: t1.setText("One Love, Listen, Nothing But the Beat");
// for combobox option david_guetta
break;
}
switch is a selection statement that successively tests the value of an expression against alist of integers or characters constants. When a match is found, the statements associated with that constant are executed. Here, the variable i is the expression(the option you choose from combobox) which is evaluated.
Hope this helps again!

How do I place more than one JComponent on the same "line" on a confirm JOptionPane?

Here's my code:
public class PaymentDialog {
public static int show(Double value) {
JLabel total = new JLabel("Total: ");
JLabel totalValue = new JLabel(value.toString());
JLabel input = new JLabel("Entrada: ");
JTextField inputField = new JTextField();
JLabel change = new JLabel("Troco: ");
JLabel changeValue = new JLabel("1234");
JComponent[] components = new JComponent[] {
total,
totalValue,
input,
inputField,
change,
changeValue
};
int result = JOptionPane.showConfirmDialog(null, components, "Pagamento", JOptionPane.OK_CANCEL_OPTION);
return result;
}
}
Here's an image of it:
As you can see, each component occupies an entire line, which is atrocious. The label should be behind it's corresponding component, instead of above it.
How do I customize this layout behavior? If it's impossible, how could I create a custom JDialog that allows me to do it? (Since I don't want to create a JFrame to customize the layout properly, as it's not the same thing).

You can add any component to the option pane. So you can create your own panel and use any layout and add any components you want.
One problem is that the text field won't have focus. Focus will be on a button of the option pane.
If you want focus on the text field then check out the RequestFocusListener found in Dialog Focus. This will allow you to control which component on the panel gets focus when the option pane is displayed.
It also contains sample code for creating a panel with a GridLayout to display on the option pane.

I'll post the code for future humans:
public class PaymentDialog {
public static int show(Double value) {
JPanel componentPanel = new JPanel();
componentPanel.setLayout(new GridLayout(3, 2));
JLabel total = new JLabel("Total: ");
JLabel totalValue = new JLabel(value.toString());
JLabel input = new JLabel("Entrada: ");
JTextField inputField = new JTextField();
JLabel change = new JLabel("Troco: ");
JLabel changeValue = new JLabel("1234");
componentPanel.add(total);
componentPanel.add(totalValue);
componentPanel.add(input);
componentPanel.add(inputField);
componentPanel.add(change);
componentPanel.add(changeValue);
int result = JOptionPane.showConfirmDialog(null, new JComponent[]{componentPanel}, "Pagamento", JOptionPane.OK_CANCEL_OPTION);
return result;
}
}

I want to replace a JLabel with another JLabel but keep it in the same position, is this possible?

Here is the code that I am trying to edit:
game = new JPanel();
ImageIcon bbb = new ImageIcon("bbb.gif");
JLabel bbbl = new JLabel(bbb);
ImageIcon bbbH = new ImageIcon("bbbH.gif");
JLabel bbbHl = new JLabel(bbbH);
game.setLayout(new GridLayout(2,2));
game.add(bbol);
game.add(bbgl);
game.add(bbgrl);
game.add(bbbl);
if (flashed == 1)
{
game.remove(bbol);
game.add(bboHl);
}
else
{
}
I want the JLabel bboHl to go in the same position as the JLabel bbol however there are other JLabels after this one, 3 more to be exact, therefor explaining why the layout is (GridLayout(2,2))
Would I need to change the layout?

Removing/adding components to the layout is way too expensive.
From what I understand, you just want to toogle an image :
Add only one JLabel, and use setIcon on it to change the image.
game = new JPanel();
ImageIcon bbb = new ImageIcon("bbb.gif");
ImageIcon bbbH = new ImageIcon("bbbH.gif");
JLabel bbbl = new JLabel(bbb);
game.setLayout(new GridLayout(2, 2));
game.add(bbol);
game.add(bbgl);
game.add(bbgrl);
game.add(bbbl);
if (flashed == 1) {
bbbl.setIcon(bbbH);
} else {
bbbl.setIcon(bbb);
}

Let say if there are multiple labels like label1 ,label2 , label3etc. And you want to set them on the position of label bbo1. Then it can be done by getting the location of label bbo1 and setting it to all other labels.
For Example
label1.setLocation(bbo1.getLocation());
label2.setLocation(bbo1.getLocation());
label3.setLocation(bbo1.getLocation());

Java JFrame not working properly in while loop

When I try to run this, I keep getting an empty frame that cannot be closed, and I have to terminate the program from eclipse. I am fairly certain that the problem is a result of the while loop (about 2/3 of the way down the code block), but I haven't been able to figure out a way to fix this
public Draw()
{
super( "Uno");
JMenuBar bar = new JMenuBar(); // create menu bar
JMenu gameMenu = new JMenu( "Play Game" );
JMenu quitMenu = new JMenu( "Quit" ); //Quit Program
bar.add( gameMenu ); // add Add menu to menu bar
bar.add( quitMenu ); // add quit button to menu bar
setJMenuBar( bar ); // set menu bar for this application
window = new JDesktopPane();
add(window);
gameMenu.addMouseListener(
new MouseListener()
{
public void mouseClicked(MouseEvent e)
{
Dimension size = window.getSize();
double height = size.getHeight();
double width = size.getWidth();
JInternalFrame frame = new JInternalFrame("Uno", true, true, true, true );
JFrame input = new JFrame();
input.setTitle(" ");
input.setSize(350, 155);
input.setLayout(new FlowLayout());
input.setLocationRelativeTo(null);
input.setVisible(true);
JLabel label1 = new JLabel("How many total players? (2-10)");
final JTextField text1 = new JTextField(3);
JLabel label2 = new JLabel("How many computer players? *");
final JTextField text2 = new JTextField(3);
JLabel label3 = new JLabel("* Computer players must be <= total number of players");
JButton confirm = new JButton("OK");
label1.setVisible(true);
label2.setVisible(true);
label3.setVisible(true);
text1.setVisible(true);
text2.setVisible(true);
confirm.setVisible(true);
input.add(label1);
input.add(text1);
input.add(label2);
input.add(text2);
input.add(label3);
input.add(confirm);
while(valid == false)
{
confirm.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String players = text1.getText();
String computers = text2.getText();
int temp1 = Integer.parseInt(players);
System.out.println("Number of players = " + temp1);
int temp2 = Integer.parseInt(computers);
System.out.println("Number of computers = " + temp2);
if (temp1 >= 2 && temp1 <= 10)
if (temp2 <= temp1 && temp2 >= 0)
valid = true;
} //close actionPerformed
}); //close ActionListener
} //close while loop
} //close mouseClicked
} //close mouseListener
} //close Draw
Initially, I was having an issue where it kept infinitely drawing the frame on top of itself because the while loop kept returning false. That issue was solved by removing the components from the while loop, and placing them before it as they are above. Now when I run it, all I get is this: picture
The goal of this program is to make an Uno game, but the first step is to determine the number of players. This is the only way I know how to do this, and this is only the second program I have done with graphics, so I am by no means an expert at Java. I will appreciate any help I can get because I have been stuck for a few days now.

The problem is that you are not giving the event handlers any chance to do their job. Your while loop continually creates event handlers. However, the actionPeformed() method can never be called because the while loop has control of the CPU and the button will not respond to any clicks.
I suggest that you learn a bit more about event handling. You will need to redesign your code in order to get the behavior you wish. Most likely you need to remove the while loop entirely and just create an event handler which will execute code when the button is clicked.
For future reference:
In general, checking equality with a boolean value is unnecessary. The result of == is a bool, but the variable you are checking is already a bool. So use it directly: instead of while (valid == false), you can do while (!valid). If you read the ! as "not", this actually makes a lot of sense.
In this case, the point is moot, since you need to remove the while loop entirely. However, this might be useful information for you some time in the future.

Adding text next to a textfield to describe what data the user is expected to enter into it

I am trying to create a simple GUI that simulates a record store. I am still in the beginning stages.
I am running into trouble when I try to add text to describe what the user is expected to enter in the text field.
In addition, I am also having trouble positioning every textfield on its own line. In other words if there is space for two textfields in one line, then it displays in one line, and I am trying to display every text field on its own line.
This is what I tried so far:
item2 = new JTextField("sample text");
However the code above just adds default text within the text field, which is not what I need :/
I appreciate all the help in advance.
public class MyClass extends JFrame{
private JTextField item1;
private JTextField item2;
public MyClass(){
super("Matt's World of Music");
setLayout(new FlowLayout());
item1 = new JTextField();
item2 = new JTextField();
add(item1);
add(item2);
thehandler handler = new thehandler();
item1.addActionListener(handler);
item2.addActionListener(handler);
}
}

For your first problem, you need to use a JLabel to display your text. The constructor is like this:
JLabel label = new JLabel("Your text here");
Works really well in GUI.
As for getting things on their own lines, I recommend a GridLayout. Easy to use.
In your constructor, before adding anything, you do:
setLayout(new GridLayout(rows,columns,x_spacing,y_spacing));
x_spacing and y_spacing are both integers that determine the space between elements horizontally and vertically.
Then add like you have done. Fiddle around with it and you'll get it worked out.
So your final would look like:
setLayout(new GridLayout(2,2,10,10));
add(new JLabel("Text 1"));
add(text1);
add(new JLabel("text 2"));
add(text2);

You could just use a JLabel to label your textfields.
JLabel label1 = new JLabel("Item 1: ");
add(label1);
add(item1);
If you really want text inside the fields, you could set the text in the field with the constructor, and then add a MouseListener to clear the text on click:
item1 = new JTextField("Text");
item1.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (item1.getText().equals("Text")) // User has not entered text yet
item1.setText("");
}
});
Or, (probably better) use a FocusListener:
item1 = new JTextField("Text");
item1.addFocusListener(new FocusListener() {
public void focusGained(FocusEvent e) {
if (item1.getText().equals("Text")) // User has not entered text yet
item1.setText("");
}
public void focusLost(FocusEvent e) {
if (item1.getText().equals("")) // User did not enter text
item1.setText("Text");
}
});
As for layout, to force a separate line, you use use a Box.
Box itemBox = Box.createVerticalBox();
itemBox.add(item1);
itemBox.add(item2);
add(itemBox);

Make:
item1 = new JTextField(10);
item2 = new JTextField(10);
that should solve problem with width of JTextField.
For beginning use GridLayout to display JTextField in one line. After that I strongly recomend using of MIG Layout http://www.migcalendar.com/miglayout/whitepaper.html.
put JLabel next to JTextField to describe what the user is expected to enter in the text field.
JLabel lbl = new JLabel("Description");
or you could also consider using of toolTipText:
item1.setToolTipText("This is description");

For making a form in Java Swing, I always recommend the FormLayout of JGoodies, which is designed to ... create forms. The links contains an example code snippet, which I just copy-pasted here to illustrate how easy it is:
public JComponent buildContent() {
FormLayout layout = new FormLayout(
"$label, $label-component-gap, [100dlu, pref]",
"p, $lg, p, $lg, p");
PanelBuilder builder = new PanelBuilder(layout);
builder.addLabel("&Title:", CC.xy(1, 1));
builder.add(titleField, CC.xy(3, 1));
builder.addLabel("&Author:", CC.xy(1, 3));
builder.add(auhtorField, CC.xy(3, 3));
builder.addLabel("&Price:", CC.xy(1, 5));
builder.add(priceField, CC.xy(3, 5));
return builder.getPanel();
}
Now for the description:
Use a label in front of the textfield to give a very short description
You can put a longer description in the textfield as suggested by #Alden. However, if the textfield is for short input, nobody will be able to read the description
You can use a tooltip (JComponent#setTooltipText) to put a longer description. Those tooltips also accept basic html which allows some formatting. Drawback of the tooltips is that the user of your application has to 'discover' that feature as there is no clear indication those are available
You can put a "help-icon" (like e.g. a question mark) after each text field (use a JButton with only an icon) where on click you show a dialog with a description (e.g. by using the JOptionPane class)
You can put one "help-icon" on each form which shows a dialog with a description for all fields.
Note for the dialog suggestion: I wouldn't make it a model one, allowing users to open the dialog and leave it open until they are finished filling in the form