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Java GUI Calculator JButton convert setText (Double)

I am trying to make an Infix to Postfix GUI calculator. I need to add normal calculator buttons to the calculator and i want there to be "PI" button that holds the value of pi. When the action is called i would like the value of "Pi" to appear in the input.setText field. However, when i attempt to do so, i run into a problem with converting the double into a type that the textField accepts.
import acm.program.*;
import acm.graphics.*; // GCanvas and G-friends
import javax.swing.*; // JButton and J-friends
import java.awt.event.ActionEvent;
import java.awt.Color;
import java.awt.Font;
public class Calc extends Program
{
JTextField input;
JTextField output;
JTextField result;
public Calc()
{
start();
setSize(500, 500);
}
public void init()
{
GCanvas canvas = new GCanvas();
add(canvas);
canvas.setBackground(Color.lightGray);
JButton conversionButton = new JButton(" DEG ");
canvas.add(conversionButton, 85, 60);
JButton conversionButton2 = new JButton("RAD");
canvas.add(conversionButton2, 170, 60);
conversionButton2.setSize(conversionButton.getSize());
JButton goButton = new JButton("Go!");
canvas.add(goButton, 280, 350);
goButton.setBackground(Color.green);
goButton.setSize(conversionButton.getSize());
JButton clearButton = new JButton("Clear");
canvas.add(clearButton, 380, 350);
clearButton.setBackground(Color.red);
clearButton.setSize(conversionButton.getSize());
JButton graphButton = new JButton("Graph");
canvas.add(graphButton, 0, 120);
graphButton.setSize(conversionButton.getSize());
JButton factorialButton = new JButton("!");
canvas.add(factorialButton, 85, 120);
factorialButton.setSize(conversionButton.getSize());
JButton ANSButton = new JButton("ANS");
canvas.add(ANSButton, 0, 90);
ANSButton.setSize(conversionButton.getSize());
JButton LnButton = new JButton("Ln");
canvas.add(LnButton, 85, 90);
LnButton.setSize(conversionButton.getSize());
JButton AbsButton = new JButton("| |");
canvas.add(AbsButton, 170, 90);
AbsButton.setSize(conversionButton.getSize());
JButton PIButton = new JButton("PI");
canvas.add(PIButton, 170, 120);
PIButton.setSize(conversionButton.getSize());
JLabel infixLabel = new JLabel("Infix");
canvas.add(infixLabel, 275, 40);
JLabel postfixLabel = new JLabel("Postfix");
canvas.add(postfixLabel, 275, 160);
JLabel resultLabel = new JLabel("Result");
canvas.add(resultLabel, 275, 280);
JLabel messageLabel = new JLabel("Note: this calculator
can only graph functions of the 3rd degree or lower");
canvas.add(messageLabel, 25, 10);
input = new JTextField();
canvas.add(input, 275, 60);
input.setSize(200, 30);
output = new JTextField();
canvas.add(output, 275, 180);
output.setSize(200, 30);
result = new JTextField();
canvas.add(result, 275, 300);
result.setSize(200, 30);
addActionListeners();
}
public void actionPerformed(ActionEvent ae)
{
String action = ae.getActionCommand();
if (action.equals("Clear"))
{
input.setText("");
output.setText("");
result.setText("");
}
else if (action.equals("Go!"))
{
// Get input from user
String c = input.getText();
result.setText(input.getText());
}
if (action.equals("PI"))
{
double Pi = 3.145926;
Double.toString(Pi);
input.setText(String.Pi);
}
}
}

Making a save button work in java

I need to build a GUI that will allow users to enter basic details about themselves for a new patient form and have that information saved to a .txt file. This data should then be viewable at a later time, but I can't get the save button to work.
//Import packages
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
//Main class
public class PatientDetailsWindow{
//Declare variables
public JFrame frame1;
public JPanel panel;
public JButton btnSave, btnExit;
public JLabel lblFirstName, lblSurname, lblGender, lblDOB, lblSmoker, lblMedHistory, lblFSlash1, lblFSlash2, lblImage;
public JTextField txtFirstName, txtSurname, txtGender, txtSmoker, txtMedHistory, txtDOB1, txtDOB2, txtDOB3;
public Insets insets;
public JTextArea textArea = new JTextArea();
public static void main (String args[]){
new PatientDetailsWindow();
}
public PatientDetailsWindow(){
createFrame();
createLabels();
createTextFields();
createButtons();
}
//Create the frame
public void createFrame(){
frame1 = new JFrame ("Personal details");
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame1.setSize (600,600);
panel = new JPanel();
panel.setBackground(Color.gray);
panel.setBounds(0, 0, 600, 600);
panel.setLayout(null);
frame1.add(panel);
frame1.setVisible(true);
}
//Creating Labels
public void createLabels(){
lblFirstName = new JLabel ("First Name: ");
lblFirstName.setBounds(50, 50, 500, 20);
lblFirstName.setForeground(Color.blue);
panel.add (lblFirstName);
lblSurname = new JLabel ("Surname: ");
lblSurname.setBounds(50, 100, 500, 20);
lblSurname.setForeground(Color.blue);
panel.add (lblSurname);
lblGender = new JLabel ("Gender: ");
lblGender.setBounds(50, 150, 500, 20);
lblGender.setForeground(Color.blue);
panel.add (lblGender);
lblDOB = new JLabel ("Date of Birth: ");
lblDOB.setBounds(50, 200, 500, 20);
lblDOB.setForeground(Color.blue);
panel.add (lblDOB);
lblFSlash1 = new JLabel ("/");
lblFSlash1.setBounds(440, 200, 20, 20);
lblFSlash1.setForeground(Color.blue);
panel.add (lblFSlash1);
lblFSlash2 = new JLabel ("/");
lblFSlash2.setBounds(490, 200, 40, 20);
lblFSlash2.setForeground(Color.blue);
panel.add (lblFSlash2);
lblSmoker = new JLabel ("Are you a smoker? ");
lblSmoker.setBounds(50, 250, 500, 20);
lblSmoker.setForeground(Color.blue);
panel.add (lblSmoker);
lblMedHistory = new JLabel ("Any other previous medical history? ");
lblMedHistory.setBounds(50, 300, 500, 20);
lblMedHistory.setForeground(Color.blue);
panel.add (lblMedHistory);
/*ImageIcon image= new ImageIcon("heartandstethoscope.jpg");
JLabel lblImage = new JLabel(image);
panel.add(lblImage);
*/
}
//Creating Text Fields
public void createTextFields(){
txtFirstName = new JTextField (10);
txtFirstName.setBounds(400, 50, 100, 20);
txtFirstName.setForeground(Color.blue);
panel.add (txtFirstName);
txtSurname = new JTextField (10);
txtSurname.setBounds(400, 100, 100, 20);
txtSurname.setForeground(Color.blue);
panel.add (txtSurname);
txtGender = new JTextField (10);
txtGender.setBounds(400, 150, 100, 20);
txtGender.setForeground(Color.blue);
panel.add (txtGender);
txtDOB1 = new JTextField (2);
txtDOB1.setBounds(400, 200, 40, 20);
txtDOB1.setForeground(Color.blue);
panel.add (txtDOB1);
txtDOB2 = new JTextField (2);
txtDOB2.setBounds(450, 200, 40, 20);
txtDOB2.setForeground(Color.blue);
panel.add (txtDOB2);
txtDOB3 = new JTextField (4);
txtDOB3.setBounds(500, 200, 80, 20);
txtDOB3.setForeground(Color.blue);
panel.add (txtDOB3);
txtSmoker = new JTextField (3);
txtSmoker.setBounds(400, 250, 100, 20);
txtSmoker.setForeground(Color.blue);
panel.add (txtSmoker);
txtMedHistory = new JTextField (300);
txtMedHistory.setBounds(400, 300, 100, 60);
txtMedHistory.setForeground(Color.blue);
panel.add (txtMedHistory);
JScrollPane areaScrollPane = new JScrollPane(txtMedHistory);
areaScrollPane.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
textArea.setBounds(400, 300, 100, 80);
JScrollPane scroll = new JScrollPane (textArea);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
textArea.setLineWrap(true);
textArea.setEditable(true);
textArea.setVisible(true);
panel.add(textArea);
}
//Creating buttons
public void createButtons(){
btnSave = new JButton ("Save");
btnSave.setBounds(130, 350, 100, 20);
btnSave.setForeground(Color.blue);
btnSave.addActionListener(new SaveHandler());
panel.add (btnSave);
btnSave.setVisible(true);
btnExit = new JButton ("Exit");
btnExit.setBounds(240, 350, 100, 20);
btnExit.setForeground(Color.blue);
btnExit.addActionListener(new ExitHandler());
panel.add (btnExit);
btnExit.setVisible(true);
}
class ExitHandler implements ActionListener{
public void actionPerformed(ActionEvent e) {
int n = JOptionPane.showConfirmDialog(frame1,
"Are you sure you want to exit?", "Exit?",JOptionPane.YES_NO_OPTION);
if(n == JOptionPane.YES_OPTION){
System.exit(0);
System.out.println("EXIT SUCCESSFUL");
}
}
}
class SaveHandler implements ActionListener{
public void actionPerformed(ActionEvent e){
try( PrintWriter out = new PrintWriter( "DetailsofPatient.txt" )){
out.println(txtFirstName.getText());
out.println(txtGender.getText());
out.println(txtDOB1.getText());
out.println(txtDOB2.getText());
out.println(txtDOB3.getText());
out.println(txtSmoker.getText());
out.println(txtMedHistory.getText());
} catch (FileNotFoundException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
System.out.println("Save successful");
}
}
}

Alright for starters, you didn't add an ActionListener to your save button, so you need to add it like this.
btnSave = new JButton ("Save");
btnSave.setBounds(130, 350, 100, 20);
btnSave.setForeground(Color.blue);
btnSave.addActionListener(new SaveHandler());
panel.add (btnSave);
btnSave.setVisible(true);
Also, in your SaveHandler, your PrintWriter isn't actually printing anything.
Your Code: out.println( ); would not write anything.
Let's say you wanted to write the contents of txtFirstName, you would need to do
out.println(txtFirstName.getText());
Edit: You also need another closing braces at the end of your ExitHandler class
class ExitHandler implements ActionListener{
public void actionPerformed(ActionEvent e) {
int n = JOptionPane.showConfirmDialog(frame1,
"Are you sure you want to exit?", "Exit?",JOptionPane.YES_NO_OPTION);
if(n == JOptionPane.YES_OPTION){
System.exit(0);
System.out.println("EXIT SUCCESSFUL");
}
}
}
You will also then need to remove a closing brace at the end of the program.

Java frame trouble

I need help with my program because I'll want to put a password and username to my program, so if the username is test && password is 12345 my program will appear a new frame but unfortunately my second didn't work for my label, button and etc here is my code so far.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class SwapFields extends JFrame{
public static void main(String[] args) {
SwapFields frameTabel = new SwapFields();
}
JButton blogin = new JButton("Login");
JPanel panel = new JPanel();
JTextField txuser = new JTextField(15);
JPasswordField pass = new JPasswordField(15);
JLabel lab = new JLabel("Username :");
JLabel pas = new JLabel("Password :");
JLabel cos;
// JPanel panel = new JPanel();
JButton y1;
JButton y2;
SwapFields() {
super("Enter Your Account !");
setSize(300, 200);
setLocation(500, 280);
panel.setLayout(null);
txuser.setBounds(90, 30, 150, 20);
pass.setBounds(90, 65, 150, 20);
blogin.setBounds(110, 100, 80, 20);
lab.setBounds(15, 28, 150, 20);
pas.setBounds(15, 63, 150, 20);
panel.add(lab);
panel.add(pas);
panel.add(blogin);
panel.add(txuser);
panel.add(pass);
getContentPane().add(panel);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
actionlogin();
}
public void actionlogin() {
blogin.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String puname = txuser.getText();
String ppaswd = pass.getText();
if (puname.equals("test") && ppaswd.equals("12345")) {
JFrame frame = new JFrame("Customer");
JPanel panel1 = new JPanel();
frame.setVisible(true);
frame.setSize(300, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cos = new JLabel("Do you have a Customer ?");
y1 = new JButton("Yes");
y2 = new JButton("No");
panel1.setLayout(null);
cos.setBounds(70, 30, 150, 20);
y1.setBounds(80, 65, 150, 20);
y2.setBounds(140, 65, 150, 20);
y1.setSize(55, 30);
y2.setSize(55, 30);
panel1.add(y1);
panel1.add(y2);
panel1.add(cos);
frame.getContentPane().add(panel1);
// this is the code ill change this is the second frame .
dispose();
} else {
JOptionPane.showMessageDialog(null, "Wrong Password / Username");
txuser.setText("");
pass.setText("");
txuser.requestFocus();
}
}
});
}
}

change
panel.setLayout(null);
to
panel.setLayout(new Flowlayout());

The java applet appears blank

I've been working at this problem for hours now, with no results. I cannot seem to get the applet to display properly when viewing the HTML page OR when running the applet through Eclipse. It is always blank. I've been searching for a long time now and decided just to ask.
Here's the code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.*;
public class Topics extends Applet{
String topicTotal = "";
JPanel topicPanel;
JLabel title, username, topic, paragraph, topicsTitle;
JTextField nameField, topicField;
JButton submitButton;
JTextArea paragraphArea;
public String getTopicTotal() {
return topicTotal;
}
public JPanel createContentPane(){
final JPanel topicGUI = new JPanel();
topicGUI.setLayout(null);
//posting panel
final JPanel postPanel = new JPanel();
postPanel.setLayout(null);
postPanel.setLocation(0, 0);
postPanel.setSize(500, 270);
topicGUI.add(postPanel);
setVisible(true);
// JLabels
JLabel title = new JLabel("Make A Post");
title.setLocation(170, 3);
title.setSize(150,25);
title.setFont(new Font("Serif", Font.PLAIN, 25));
title.setHorizontalAlignment(0);
postPanel.add(title);
JLabel username = new JLabel("Username: ");
username.setLocation(20, 30);
username.setSize(70,15);
username.setHorizontalAlignment(0);
postPanel.add(username);
JLabel topic = new JLabel("Topic: ");
topic.setLocation(20, 50);
topic.setSize(40,15);
topic.setHorizontalAlignment(0);
postPanel.add(topic);
JLabel paragraph = new JLabel("Paragraph: ");
paragraph.setLocation(20, 70);
paragraph.setSize(70,15);
paragraph.setHorizontalAlignment(0);
postPanel.add(paragraph);
// JTextFields
nameField = new JTextField(8);
nameField.setLocation(90, 30);
nameField.setSize(150, 18);
postPanel.add(nameField);
topicField = new JTextField(8);
topicField.setLocation(60, 50);
topicField.setSize(180, 18);
postPanel.add(topicField);
// JTextAreas
paragraphArea = new JTextArea(8, 5);
paragraphArea.setLocation(20, 85);
paragraphArea.setSize(450, 100);
paragraphArea.setLineWrap(true);
paragraphArea.setEditable(true);
JScrollPane scrollParagraph = new JScrollPane (paragraphArea);
scrollParagraph.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
postPanel.add(paragraphArea);
// JButton
JButton submitButton = new JButton("SUBMIT");
submitButton.setLocation(250, 30);
submitButton.setSize(100, 30);
submitButton.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
topicTotal = topicTotal + "/n" + nameField + "/n" + topicTotal + "/n" + paragraphArea + "/n";
}
});
postPanel.add(submitButton);
setVisible(true);
return topicGUI;
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("");
Topics display = new Topics();
frame.setContentPane(display.createContentPane());
frame.setSize(500, 270);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

In order to run as an applet, you need to override the init method. You don't need a main method. Just add all you components inside the init method
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.*;
public class Topics extends Applet {
String topicTotal = "";
JPanel topicPanel;
JLabel title, username, topic, paragraph, topicsTitle;
JTextField nameField, topicField;
JButton submitButton;
JTextArea paragraphArea;
public String getTopicTotal() {
return topicTotal;
}
public void init() {
final JPanel topicGUI = new JPanel();
topicGUI.setLayout(null);
// posting panel
final JPanel postPanel = new JPanel();
postPanel.setLayout(null);
postPanel.setLocation(0, 0);
postPanel.setSize(500, 270);
add(postPanel);
setVisible(true);
// JLabels
JLabel title = new JLabel("Make A Post");
title.setLocation(170, 3);
title.setSize(150, 25);
title.setFont(new Font("Serif", Font.PLAIN, 25));
title.setHorizontalAlignment(0);
add(title);
JLabel username = new JLabel("Username: ");
username.setLocation(20, 30);
username.setSize(70, 15);
username.setHorizontalAlignment(0);
add(username);
JLabel topic = new JLabel("Topic: ");
topic.setLocation(20, 50);
topic.setSize(40, 15);
topic.setHorizontalAlignment(0);
add(topic);
JLabel paragraph = new JLabel("Paragraph: ");
paragraph.setLocation(20, 70);
paragraph.setSize(70, 15);
paragraph.setHorizontalAlignment(0);
add(paragraph);
// JTextFields
nameField = new JTextField(8);
nameField.setLocation(90, 30);
nameField.setSize(150, 18);
add(nameField);
topicField = new JTextField(8);
topicField.setLocation(60, 50);
topicField.setSize(180, 18);
add(topicField);
// JTextAreas
paragraphArea = new JTextArea(8, 5);
paragraphArea.setLocation(20, 85);
paragraphArea.setSize(450, 100);
paragraphArea.setLineWrap(true);
paragraphArea.setEditable(true);
JScrollPane scrollParagraph = new JScrollPane(paragraphArea);
scrollParagraph
.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
add(paragraphArea);
// JButton
JButton submitButton = new JButton("SUBMIT");
submitButton.setLocation(250, 30);
submitButton.setSize(100, 30);
submitButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
topicTotal = topicTotal + "/n" + nameField + "/n" + topicTotal
+ "/n" + paragraphArea + "/n";
}
});
add(submitButton);
}
}

Java swing/awt tabbed pane event

I'm new to java so bear with me:
I want the size of the window/pane/panel to chance once the tab is clicked/changed.
How would I do/impletement this?
I've done it successfully on a button click/event, but how do I do a tab click/event?
Here is my code: (I'm sorry for any bad/bloated/unnessicary code in advance)
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
//Class shows how to setup up a tabbed window
public class GUI implements ActionListener
{
static JFrame aWindow = new JFrame("Project");
JTabbedPane myTabs = new JTabbedPane();
JPanel loginMainPanel = new JPanel();
JPanel displayMainPanel = new JPanel();
JPanel editMainPanel = new JPanel();
JLabel loginLabel = new JLabel("Username:");
JTextField loginField = new JTextField();
JLabel loginLabel2 = new JLabel("Password:");
JPasswordField loginPass = new JPasswordField();
JButton displayButton = new JButton("Press This Button");
JButton loginButton = new JButton("Login");
JLabel editLabel = new JLabel("Write a story:");
JTextArea editArea = new JTextArea();
public GUI()
{
Toolkit theKit = aWindow.getToolkit();
Dimension wndSize=theKit.getScreenSize();
aWindow.setBounds(wndSize.width/3, wndSize.height/3, 200, 200); //set position, then dimensions
aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GridLayout grid = new GridLayout(1,1);
Container content = aWindow.getContentPane();
content.setLayout(grid);
createLoginPanel();
createDisplayPanel();
createEditPanel();
myTabs.addTab("Login", loginMainPanel);
myTabs.addTab("Display", displayMainPanel);
myTabs.addTab("Edit", editMainPanel);
myTabs.setSelectedIndex(0);
//myTabs.setEnabledAt(1,false);
myTabs.setEnabledAt(2, false);
content.add(myTabs);
aWindow.setVisible(true);
}
public void createLoginPanel()
{
loginMainPanel.setLayout(null);
loginLabel.setBounds(10, 15, 150, 20);
loginMainPanel.add(loginLabel);
loginField.setBounds(10, 35, 150, 20);
loginMainPanel.add(loginField);
loginLabel2.setBounds(10, 60, 150, 20);
loginMainPanel.add(loginLabel2);
loginPass.setBounds(10, 80, 150, 20);
loginMainPanel.add(loginPass);
loginButton.addActionListener(this);
loginButton.setBounds(50, 110, 80, 20);
loginMainPanel.add(loginButton);
}
public void createDisplayPanel()
{
//Toolkit theKit = aWindow.getToolkit();
//Dimension wndSize = theKit.getScreenSize();
//aWindow.setBounds(20, 20, 20, 20); //set position, then dimensions
displayMainPanel.setLayout(null);
displayButton.addActionListener(this);
displayButton.setBounds(10, 80, 150, 20);
displayMainPanel.add(displayButton);
}
public void createEditPanel()
{
editMainPanel.setLayout(null);
editLabel.setBounds(10, 15, 150, 20);
editMainPanel.add(editLabel);
editArea.setBounds(10, 65, 150, 50);
editMainPanel.add(editArea);
}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == loginButton)
{
//System.out.println("Working...");
Toolkit theKit = aWindow.getToolkit();
Dimension wndSize = theKit.getScreenSize();
aWindow.setBounds(wndSize.width / 4, wndSize.height / 4, 300, 300);
}
//Would the event go here?
}
public static void main(String[] args)
{
GUI tw1 = new GUI();
}
}
Thanks very much :)
James,

but how do I do a tab click/event?
Use a ChangeListener.