Develop Reference

I've created a basic GUI but buttons won't interact with textfield

I've been working on creating a simple GUI through the use of JPanels. I've managed to what I believe fluke a reasonably looking layout and now I would like the user to be able to input values into the Mass textbox and the Acceleration textbox so when they hit calculate they are given a message telling them the Force.
The issue I am having is within the public void that is added to the buttons, I can't seem to figure out how to refer to values within the text field. I've tried to just refer to it generally by:
String mass = txts[1].getText();
However this doesn't recognise txts as existing?
Any help on this would be much appreciated.
Below is the full code in case it helps.
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.event.*;
import java.awt.*;
public class InitScreen {
public static void createHomeScreen() {
/*Creates a Java Frame with the Window Name = HomeScreen*/
JFrame frame = new JFrame("HomeScreen");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
frame.getContentPane().setPreferredSize(new Dimension(400,300));
frame.pack();
/*Creates the main JPanel in form of GridLayout*/
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
mainPanel.setBorder(new EmptyBorder(new Insets(20,20,20,20)));
/*Creates the first sub panel*/
JPanel firstPanel = new JPanel();
firstPanel.setLayout(new GridLayout(1,2,75,100));
firstPanel.setMaximumSize(new Dimension(300,100));
/*Creates the buttons in the first sub panel*/
JButton[] btns = new JButton[2];
String bText[] = {"Calculate", "Clear"};
for (int i=0; i<2; i++) {
btns[i] = new JButton(bText[i]);
btns[i].setPreferredSize(new Dimension(100, 50));
btns[i].setActionCommand(bText[i]);
btns[i].addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
String choice = e.getActionCommand();
/*JOptionPane.showMessageDialog(null, "Clicked "+choice);*/
JOptionPane.showMessageDialog(null, "Force = ");
}
});
firstPanel.add(btns[i]);
}
/*Creates the second sub panel*/
JPanel secondPanel = new JPanel();
secondPanel.setLayout(new BorderLayout());
/*Creates the labels for the second sub panel*/
JLabel label = new JLabel("Calculate the Force of an Object", SwingConstants.CENTER);
secondPanel.add(label,BorderLayout.NORTH);
/*Creates the third sub Panel for entering values*/
JPanel thirdPanel = new JPanel();
thirdPanel.setLayout(new GridLayout(3,1,10,10));
thirdPanel.setMaximumSize(new Dimension(400,100));
/*Create labels and text fields for third sub panel*/
String lText[] = {"Mass of Body", "Acceleration of Body", "Force"};
JLabel[] lbls = new JLabel[3];
JTextField[] txts = new JTextField[3];
for (int i=0; i<3; i++) {
txts[i] = new JTextField();
lbls[i] = new JLabel(lText[i], SwingConstants.LEFT);
lbls[i].setPreferredSize(new Dimension(50, 50));
thirdPanel.add(lbls[i]);
thirdPanel.add(txts[i]);
}
mainPanel.add(secondPanel);
mainPanel.add(thirdPanel);
mainPanel.add(firstPanel);
frame.setContentPane(mainPanel);
frame.setVisible(true);
}
public static void main(final String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createHomeScreen();
}
});
}
}

First drop the reliance on static, and instead, create an instance of InitScreen and call it's createHomeScreen method
public class InitScreen {
public void createHomeScreen() {
//...
}
public static void main(final String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
InitScreen screen = new InitScreen();
screen.createHomeScreen();
}
});
}
Now, make txts and instance field of InitScreen and use it within your methods
public class InitScreen {
private JTextField[] txts;
public void createHomeScreen() {
//...
txts = new JTextField[3];
//...
}
This takes txts from a local context to a class instance context, meaning you can now access it from any method within InitScreen

Java GUI - Possible to store JPanels inside a single main JPanel?

I am working on a semester project that I have and I was wondering if it was possible to store 3-4 JPanels instead one single "main" JPanel. The reason for me asking this is because I a trying to make a GUI checkbook program and my checkbook has 7 buttons that should open a new window once I click on it. To switch between each window I'm going to have to use the CardLayout, but my understand of the CardLayout is that I can only assign one single JPanel to that card so I can't assign multiple JPanels to a single Card layout so when the user clicks on a different card 3-4 different JPanels appear.
The reason that I am asking this is because I asked for help earlier and received help for creating my first window in this project, it produces the output I want PERFECTLY, but uses more than 1 JPanel in doing so. Since this prevents me from continuing on to the other steps of my 7 GUI Windows, I am stuck.
Here is the code:
import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class checkbook extends JPanel implements ActionListener {
private static final String title = "Use The Buttons Below To Manage Transactions";
private static final String[] bottomButtons = { "Create a New Account",
"Load a Trans from a File", "Add New Transactions",
"Search Transactions", "Sort Transactions",
"View/Delete Transactions", "Backup Transaction", "Exit" };
static JButton Button[] = new JButton[8];
static ActionListener AL = new checkbook();
public checkbook() {
JLabel titleLabel = new JLabel(title, SwingConstants.CENTER);
titleLabel.setFont(titleLabel.getFont().deriveFont(Font.BOLD, 18));
JPanel titlePanel = new JPanel();
titlePanel.add(titleLabel); // put it in a JPanel so it will expand to fill BoxLayout
JTextField textfield = new JTextField();
JPanel accountBalancePanel = new JPanel();
accountBalancePanel.add(new JLabel("Account Name:"));
accountBalancePanel.add(new JTextField(10));
accountBalancePanel.add(Box.createHorizontalStrut(4));
accountBalancePanel.add(new JLabel("Balance:"));
textfield = new JTextField("0.0", 10);
textfield.setHorizontalAlignment(JTextField.RIGHT);
accountBalancePanel.add(textfield);
JPanel northPanel = new JPanel();
northPanel.setLayout(new BoxLayout(northPanel, BoxLayout.PAGE_AXIS));
northPanel.add(titlePanel);
northPanel.add(accountBalancePanel);
JPanel southBtnPanel = new JPanel(new GridLayout(2, 4, 1, 1));
for(int i = 0; i < 8; i++){
Button[i] = new JButton(bottomButtons[i]);
southBtnPanel.add(Button[i]);
Button[i].addActionListener(AL);
}
setBorder(BorderFactory.createEmptyBorder(1, 1, 1, 1));
setLayout(new BorderLayout());
add(northPanel, BorderLayout.NORTH);
add(Box.createRigidArea(new Dimension(100, 100))); // just an empty placeholder
add(southBtnPanel, BorderLayout.SOUTH);
}
private static void createAndShowGui() {
checkbook mainPanel = new checkbook();
JFrame frame = new JFrame("Checkbook");
frame.setDefaultCloseOperation(JFrame.DISPOSE_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();
}
});
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == Button[7]) {
System.exit(0);
}
}
}
Credit goes to Hovercraft Full Of Eels for showing me the above example
If there is anything that is unclear about my question, please ask and I will do the best I can to fix it.
Here is what the code produces:
http://i.stack.imgur.com/WY0c3.png

Button Layout Issues with JFrame

Picture included I have another issue where my buttons go to the top-right after the user inputs their name. At this point, text shows up in the GUI on the LEFT side of the center which seems it would be "WEST" when I put "CENTER". Code:
public TheDungeon()
{
setTitle("InsertGameNameHere");
setSize(750, 600);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
setLocationRelativeTo(null);
buildButtonPanel();
characterInfoPanel = new JLabel("<html>Character information will go here</html>");
gameScreen = new JLabel();
inventoryPanel = new JLabel("<html>This is for the inventory</html>");
add(gameScreen, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
setVisible(true);
//Program run
userName();
gameScreen.setText("<html>Welcome "+name+", to the game that has no name!</html>");
classWindow();
}
private void buildButtonPanel()
{
// Create a panel for the buttons.
buttonPanel = new JPanel();
// Create the buttons.
b1 = new JButton("Button 1");
b2 = new JButton("Button 2");
b3 = new JButton("Button 3");
b4 = new JButton("Button 4");
b5 = new JButton("Button 5");
// Add the buttons to the button panel.
buttonPanel.add(b1);
buttonPanel.add(b2);
buttonPanel.add(b3);
buttonPanel.add(b4);
buttonPanel.add(b5);
}
private void userName() {
name = JOptionPane.showInputDialog("What will your name be?");
}

I'm not sure why your program is behaving as it seems to be since when I ran it, it did not do this. You may wish to check your code to make sure that it's the code you're posting here. But regardless, I do have some suggestions:
Best to not set the sizes of anything, but rather to let the components and the layout managers do this for you.
Consider if you must overriding getPreferredSize() if you need to control the size of a component more fully.
Call pack() on your top level window after adding all components and before calling setVisible(true). This will tell the layout managers to do their things.
Avoid extending JFrame since you will rarely need to override one of its innate behaviors.
If you do add or remove components, or change their preferredSizes somehow after rendering your top-level window, you will want to call revalidate() and then repaint() on the component's container to have the container re-layout the components it holds and then redraw them.
For example:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.*;
public class TheDungeon2 extends JPanel {
private static final int PREF_W = 750;
private static final int PREF_H = 600;
private static final String[] BUTTON_LABELS = {"Button 1", "Button 2",
"Button 3", "Button 4", "Button 5"};
private static final String WELCOME_TEXT = "Welcome %s to the game that has no name!";
private JLabel welcomeLabel = new JLabel("", SwingConstants.CENTER);
private String name;
public TheDungeon2() {
JPanel buttonPanel = new JPanel(new GridLayout(1, 0, 5, 0));
for (String buttonLabel : BUTTON_LABELS) {
JButton button = new JButton(buttonLabel);
buttonPanel.add(button);
}
setLayout(new BorderLayout());
add(welcomeLabel, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.PAGE_END);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
public void getAndSetName() {
name = JOptionPane.showInputDialog(this, "What will your name be?");
welcomeLabel.setText(String.format(WELCOME_TEXT, name));
}
private static void createAndShowGui() {
TheDungeon2 dungeon2 = new TheDungeon2();
JFrame frame = new JFrame("Nameless Game");
dungeon2.getAndSetName();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(dungeon2);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

I tested your code with an empty classWindow() method and the buttons are correctly placed in south,
for the CENTER issue, you should place something in WEST to have your text centred (even an empty panel) otherwise CENTER will take all the place,
look at this , i added this line :
add(new JButton("a button for test"),BorderLayout.WEST);
and here is the result :

Unstable GUI in Java

I am writing a very simple GUI, that contains 3 buttons, 2 labels, 2 text fields and one text area. Strangely, the result is unstable: when running the class the GUI appears with random number of the controls. I tried various layout managers, changing the order among the control - nothing.
Can someone help?
package finaltestrunner;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class FinalTestGUI extends JFrame implements ActionListener
{
public Boolean startState = false;
JButton sofButton;
JButton startStopButton;
JButton exitButton;
JTextField loopCounts;
JTextField trSnField;
JTextArea resultField = null;
public FinalTestGUI()
{
// The constructor creates the panel and places the controls
super(); // Jframe constructor
JFrame trFrame = new JFrame();
trFrame.setSize(1000, 100);
trFrame.setVisible(true);
trFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
trFrame.setTitle("Test runner");
setFont(new Font("SansSerif", Font.PLAIN, 14));
// trFrame.setLayout(new FlowLayout());
JPanel trControlPanel = new JPanel();
trControlPanel.setSize(1000, 100);
trControlPanel.setLayout(new GridLayout(1,7));
exitButton = new JButton("Exit");
trControlPanel.add(exitButton);
startStopButton = new JButton("Run ");
trControlPanel.add(startStopButton);
JLabel loopsLabel = new JLabel ("Loops count: ");
trControlPanel.add(loopsLabel);
loopCounts = new JTextField (5);
trControlPanel.add(loopCounts);
sofButton = new JButton("SoF");
trControlPanel.add(sofButton);
JLabel testLabel = new JLabel ("serial Number: ");
trControlPanel.add(testLabel);
trSnField = new JTextField (5);
trControlPanel.add(trSnField);
JTextArea trResultField = new JTextArea (80, 10);
trFrame.add(trControlPanel);
// cpl.add(trResultField);
startStopButton.addActionListener(new ActionListener()
{
#Override
public void actionPerformed (ActionEvent trStartStopButton)
{
startState = !startState;
if (startState)
{
startStopButton.setText("Run ");
startStopButton.setForeground(Color.red);
}
else
{
startStopButton.setText("Stop");
startStopButton.setForeground(Color.green);
}
}
});
sofButton.addActionListener(new ActionListener()
{
#Override
public void actionPerformed (ActionEvent trSofButton)
{
loopCounts.setText("SOF\n");
}
});
exitButton.addActionListener (new ActionListener()
{
#Override
public void actionPerformed (ActionEvent trExitButton)
{
System.exit(0);
}
});
} // End of the constructor
#Override
public void actionPerformed (ActionEvent ae) { }
public void atpManager ()
{
String selectedAtp = "";
}
}

There are a couple of issues with this code:
You are already inheriting from JFrame, so you do not need to create yet another JFrame
You are showing your frame with setVisible(true) and afterwards adding components to it. This invalidates your layout, you need to revalidate afterwards (or move setVisible() to a position where you already added your components)
You are adding your components to the JFrame directly, but you need to use its contentpane. Starting with Java 1.5, the JFrame.add() methods automatically forward to the content pane. In earlier versions, it was necessary to retrieve the content pane with JFrame.getContentPane() to add the child components to the content pane.
Try this:
public FinalTestGUI() {
// The constructor creates the panel and places the controls
super(); // Jframe constructor
setSize(1000, 100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Test runner");
setFont(new Font("SansSerif", Font.PLAIN, 14));
setLayout(new FlowLayout());
JPanel trControlPanel = new JPanel();
trControlPanel.setSize(1000, 100);
trControlPanel.setLayout(new GridLayout(1,7));
exitButton = new JButton("Exit");
trControlPanel.add(exitButton);
startStopButton = new JButton("Run ");
trControlPanel.add(startStopButton);
JLabel loopsLabel = new JLabel ("Loops count: ");
trControlPanel.add(loopsLabel);
loopCounts = new JTextField (5);
trControlPanel.add(loopCounts);
sofButton = new JButton("SoF");
trControlPanel.add(sofButton);
JLabel testLabel = new JLabel ("serial Number: ");
trControlPanel.add(testLabel);
trSnField = new JTextField (5);
trControlPanel.add(trSnField);
JTextArea trResultField = new JTextArea (80, 10);
// getContentPane().add(trControlPanel); // pre 1.5
add(trControlPanel); // 1.5 and greater
setVisible(true);
}

Working with JFrames

hi I'm basically give up. Ok so this is what I am trying to do. So far I have written code to create a JFrame which contains a text field and combo box. The code is supposed to calculate the area of an input in the text field depending on what shape is selected from the combo box and output the result on the JFrame!
Here's is what the output should look like
And here is my code so far. it's a bit messed up but any help would be much appreciated. Thanks in advance
import javax.swing. *;
import java.awt.event. *;
import java.awt.FlowLayout;
import java.lang.Math;
public class AreaFrame3 extends JFrame
{
double Area;
double input;
public static void main(String[]args)
{
//Create array containing shapes
String[] shapes ={"(no shape selected)","Circle","Equilateral Triangle","Square"};
//Use combobox to create drop down menu
JComboBox comboBox=new JComboBox(shapes);
JLabel label1 = new JLabel("Select shape:");
JPanel panel1 = new JPanel(new FlowLayout()); //set frame layout
JLabel label2 = new JLabel("(select shape first)");
JTextField text = new JTextField(10); //create text field
text.setEnabled(false);
panel1.add(label1);
panel1.add(comboBox);
panel1.add(label2);
panel1.add(text);
JFrame frame=new JFrame("Area Calculator Window");//create a JFrame to put combobox
frame.setLayout(new FlowLayout()); //set layout
frame.add(panel1);
frame.add(text);
//JButton button = new JButton("GO"); //create GO button
//frame.add(button);
//set default close operation for JFrame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
//set JFrame ssize
frame.setSize(400,250);
//make JFrame visible. So we can see it
frame.setVisible(true);
// public void actionPerformed(ActionEvent e)
//{
}
public void AreaCalc()
{
JButton button = new JButton("GO"); //create GO button
frame.add(button);
button.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e)
{
int input = double.parseDouble(text.getText());
if(e.getSource() == button)
{
String shape = (String).comboBox.getSelectedItem();
if(shape == "(no shape selected)")
{
text.setEnabled(false);
}
else{
text.setEnabled(true);
}
if(input > 1 && shape == "Circle")
{
// label2.getText() = "Enter the radius of the circle: ";
Area = (Math.PI * (input * input));
}
}
else{}
}
}
);
}
}

I try to understand what you did here:
panel1.add(label1);
panel1.add(comboBox);
panel1.add(label2);
panel1.add(text); // <---
JFrame frame=new JFrame("Area Calculator Window");//create a JFrame to put combobox
frame.setLayout(new FlowLayout()); //set layout
frame.add(panel1);
frame.add(text); // <---
Especially frame.add(text); and panel1.add(text);. Don't add text to JFrame. Use JPanel.
Further,
public class AreaFrame3 extends Frame
Use public class AreaFrame3 extends JFrame so you don't need create additional JFrame:
JFrame frame=new JFrame("Area Calculator Window");
Something like:
super.setLayout(new FlowLayout()); //set layout
super.add(panel1);
super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
super.pack();
//set JFrame ssize
super.setSize(400,250);
//make JFrame visible. So we can see it
super.setVisible(true);
At last Ill give you some tamplate to start with (that will help you):
public class FrameExmpl extends JFrame{
private static final long serialVersionUID = 1L;
private JTabbedPane tabbedPane;
private JPanel topPanel;
private JTextField txtf_loadDS_;
public static int valueInt = 0; // responsible for Task status updating
public static Boolean isFinish = false;
public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException{
UIManager.setLookAndFeel( "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" );
FrameExmpl UI_L = new FrameExmpl();
UI_L.buildGUI();
UI_L.setVisible(true);
}
public void buildGUI(){
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
dispose();
}
});
setSize(435, 225);
setLocation(285, 105);
setResizable(false);
topPanel = new JPanel();
topPanel.setLayout(new BorderLayout());
getContentPane().add(topPanel);
txtf_loadDS_ = new JTextField();
txtf_loadDS_.setBounds(22, 22, 382, 25);
topPanel.add(txtf_loadDS_);
finishBuildGUI();
}
public void finishBuildGUI(){
tabbedPane = new JTabbedPane();
topPanel.add(tabbedPane, BorderLayout.CENTER);
}
}

There are multiple issues with this application such as extending from Frame rather than JFrame & attempting to assign an int from Double.parseDouble. I would recommend that you start again building a small but working application and incrementally add functionality, this way errors are easier to fix.