JTextField返回用户输入为零

Question

double myintc;
        double myint1;
         double calW;

final JTextField WeightField = new JTextField();
        WeightField.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                //String s = WeightField.getText();
             myintc = Double.parseDouble(WeightField.getText());

calW = myintc*1.5;
        calA =myint1*2.2;

final JButton button = new JButton("Continue");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            // Proceeding to Payment Interface when we Click Continue Buttom    
                ChickenPay window = new ChickenPay();
                window.frmChickenPurchase.setVisible(true);
                frmChicjenPurchase.setVisible(false);
                JOptionPane.showMessageDialog(button, "Abbattoir is equal to  "+ calW);

After user input of number. to Get calW it always output 0 also myintc says null

 myintc = Double.parseDouble(WeightField.getText());

I tried calW= Double.parseDouble(WeightField.getText()) *1.5;

I still get error. Please help

http://i.stack.imgur.com/14ul2.png

This is the whole code

package pos;

import java.awt.EventQueue;
import pos.ChickenPay;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import java.awt.BorderLayout;

import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.BoxLayout;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import java.awt.Window;
import java.awt.Choice;
import javax.swing.JFormattedTextField;
import javax.swing.JCheckBox;
import java.awt.Color;
import java.awt.Font;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import java.awt.TextField;

public class ChickenSales {


    JFrame frmChicjenPurchase;
    private JTextField textField;
    public static int ws;
    public static int ab;
    public double myintc;
    double myint1;
    public static double calW;
    public static double calA;
    int tPrice;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    ChickenSales window = new ChickenSales();
                    window.frmChicjenPurchase.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public ChickenSales() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmChicjenPurchase = new JFrame();
        frmChicjenPurchase.setTitle("Chicken Purchase");
        frmChicjenPurchase.setSize(400, 300);
        frmChicjenPurchase.setLocationRelativeTo(null);
        frmChicjenPurchase.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        GridBagLayout gridBagLayout = new GridBagLayout();
        gridBagLayout.columnWidths = new int[]{0, 0, 0, 0, 0, 0, 0, 0, 0};
        gridBagLayout.rowHeights = new int[]{55, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
        gridBagLayout.columnWeights = new double[]{1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, Double.MIN_VALUE};
        gridBagLayout.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, Double.MIN_VALUE};
        frmChicjenPurchase.getContentPane().setLayout(gridBagLayout);

        JLabel lblChickenInformation = new JLabel("Chicken Information");
        lblChickenInformation.setFont(new Font("Calisto MT", Font.BOLD, 16));
        lblChickenInformation.setForeground(new Color(0, 0, 0));
        GridBagConstraints gbc_lblChickenInformation = new GridBagConstraints();
        gbc_lblChickenInformation.gridwidth = 4;
        gbc_lblChickenInformation.insets = new Insets(0, 0, 5, 5);
        gbc_lblChickenInformation.gridx = 3;
        gbc_lblChickenInformation.gridy = 0;
        frmChicjenPurchase.getContentPane().add(lblChickenInformation, gbc_lblChickenInformation);

        JLabel lblWeight = new JLabel("Weight (kg)");
        GridBagConstraints gbc_lblWeight = new GridBagConstraints();
        gbc_lblWeight.gridwidth = 3;
        gbc_lblWeight.insets = new Insets(0, 0, 5, 5);
        gbc_lblWeight.gridx = 2;
        gbc_lblWeight.gridy = 1;
        frmChicjenPurchase.getContentPane().add(lblWeight, gbc_lblWeight);

        final JTextField WeightField = new JTextField();
        WeightField.addActionListener(new ActionListener( ) {
            public void actionPerformed(ActionEvent e) {
                //String s = WeightField.getText();
            // myintc = Double.parseDouble(WeightField.getText());

            }
        });
        WeightField.setColumns(5);
        WeightField.setToolTipText("Enter Weight betwwen 2-8 kg");
        GridBagConstraints gbc_WeightField = new GridBagConstraints();
        gbc_WeightField.anchor = GridBagConstraints.WEST;
        gbc_WeightField.insets = new Insets(0, 0, 5, 0);
        gbc_WeightField.gridx = 7;
        gbc_WeightField.gridy = 1;
        frmChicjenPurchase.getContentPane().add(WeightField, gbc_WeightField);

        JLabel lblAge = new JLabel("Age");
        GridBagConstraints gbc_lblAge = new GridBagConstraints();
        gbc_lblAge.insets = new Insets(0, 0, 5, 5);
        gbc_lblAge.gridx = 3;
        gbc_lblAge.gridy = 3;
        frmChicjenPurchase.getContentPane().add(lblAge, gbc_lblAge);

        final JFormattedTextField AgeField = new JFormattedTextField();
        AgeField.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                //String B = AgeField.getText();
                try{

                    myint1 = Double.parseDouble(AgeField.getText());
                            if(myint1>=6 && myint1 <=24){

                            }
                                        }
                catch (Exception e1){
                    System.out.println("Weight ranges between 2-8kg");

                }
                            }
            //END AGE HERE
        });
        AgeField.setToolTipText("Enter Age betwwen 6-24 months");
        AgeField.setColumns(5);
        GridBagConstraints gbc_AgeField = new GridBagConstraints();
        gbc_AgeField.anchor = GridBagConstraints.WEST;
        gbc_AgeField.insets = new Insets(0, 0, 5, 0);
        gbc_AgeField.gridx = 7;
        gbc_AgeField.gridy = 3;
        frmChicjenPurchase.getContentPane().add(AgeField, gbc_AgeField);

        JLabel lblBreed = new JLabel("Breed");
        GridBagConstraints gbc_lblBreed = new GridBagConstraints();
        gbc_lblBreed.insets = new Insets(0, 0, 5, 5);
        gbc_lblBreed.gridx = 3;
        gbc_lblBreed.gridy = 5;
        frmChicjenPurchase.getContentPane().add(lblBreed, gbc_lblBreed);

        // ACTION LISTENER 4 BREED
        final Choice BreedChoice = new Choice();
        BreedChoice.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {

                String wa = BreedChoice.getSelectedItem();
                switch (wa){
                case "W":
                 ws =100;
                    break;
                case "X":
                     ws =150;
                        break;
                case "Y":
                     ws =200;
                        break;
                case "Z":
                     ws =350;
                        break;
                    default:


                }



            }
        });

        BreedChoice.add("--");
        BreedChoice.add("W");
        BreedChoice.add("X");
        BreedChoice.add("Y");
        BreedChoice.add("Z");




        GridBagConstraints gbc_BreedChoice = new GridBagConstraints();
        gbc_BreedChoice.insets = new Insets(0, 0, 5, 0);
        gbc_BreedChoice.anchor = GridBagConstraints.WEST;
        gbc_BreedChoice.gridx = 7;
        gbc_BreedChoice.gridy = 5;
        frmChicjenPurchase.getContentPane().add(BreedChoice, gbc_BreedChoice);

        JLabel lblAbattoir = new JLabel("Abattoir Service");
        GridBagConstraints gbc_lblAbattoir = new GridBagConstraints();
        gbc_lblAbattoir.insets = new Insets(0, 0, 5, 5);
        gbc_lblAbattoir.gridx = 3;
        gbc_lblAbattoir.gridy = 7;
        frmChicjenPurchase.getContentPane().add(lblAbattoir, gbc_lblAbattoir);

        final JCheckBox abbattoirCheckBox = new JCheckBox("");
        abbattoirCheckBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            boolean selected = abbattoirCheckBox.getModel().isSelected();
            if (selected){
                ab =50;
            }
            }
        });

        //LOGIC STARTS HERE
        calW = myintc*1.5;
        calA =myint1*2.2;



        //---------------


        abbattoirCheckBox.setToolTipText("Costs N50");
        GridBagConstraints gbc_abbattoirCheckBox = new GridBagConstraints();
        gbc_abbattoirCheckBox.insets = new Insets(0, 0, 5, 0);
        gbc_abbattoirCheckBox.anchor = GridBagConstraints.WEST;
        gbc_abbattoirCheckBox.gridx = 7;
        gbc_abbattoirCheckBox.gridy = 7;
        frmChicjenPurchase.getContentPane().add(abbattoirCheckBox, gbc_abbattoirCheckBox);

        final JButton button = new JButton("Continue");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            // Proceeding to Payment Interface when we Click Continue Buttom    
                ChickenPay window = new ChickenPay();
                window.frmChickenPurchase.setVisible(true);
                frmChicjenPurchase.setVisible(false);
                JOptionPane.showMessageDialog(button, "Abbattoir is equal to  "+ calW);
            }
        });
        GridBagConstraints gbc_button = new GridBagConstraints();
        gbc_button.anchor = GridBagConstraints.ABOVE_BASELINE;
        gbc_button.insets = new Insets(0, 0, 5, 5);
        gbc_button.gridx = 5;
        gbc_button.gridy = 8;
        frmChicjenPurchase.getContentPane().add(button, gbc_button);



        JPanel marginPanel = new JPanel();
        marginPanel.setBounds(5, 5, 5, 5);
        GridBagConstraints gbc_marginPanel = new GridBagConstraints();
        gbc_marginPanel.insets = new Insets(0, 0, 0, 5);
        gbc_marginPanel.fill = GridBagConstraints.BOTH;
        gbc_marginPanel.gridx = 0;
        gbc_marginPanel.gridy = 9;
        frmChicjenPurchase.getContentPane().add(marginPanel, gbc_marginPanel);






    }

}

Answer 1

A JTextField 's action listener is only called when Enter is pressed while the focus is in the JTextField . If the user types a number in the field, and then tabs away, or clicks a button, then the action listener will not be called, so your variable myintc will remain uninitialized.

The parsing of the JTextField should be moved into the button's action listener, to ensure it is performed when the Continue button is pressed.

eg)

final JTextField WeightField = new JTextField();
// (no action listener required here)

final JButton button = new JButton("Continue");
button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        myintc = Double.parseDouble(WeightField.getText());
        calW = myintc*1.5;
        // Remainder of "Proceeding to Payment" code
    }
});

Answer 2

After user input of number. to Get calW it always output 0 also myintc says null

calW is always zero, because in your entire codes, you did not change its value at all.

The only place where you assigned a value to it is in the initialize() method. However you assign it as:

calW = myintc*1.5;  //myintc is 0!

---

myintc was not initialized at all, hence a default 0 value will be assigned to it, causing calW to be initialized to 0 as well.

Since calW was initialized as zero and there is no further update on this variable, you always get 0 for calW .

---

Some Suggestions:

• You are creating too many static variables and your implementation code was thrown in one huge class. You don't need static variables for a program like this. Instead, you can create customized container class such as a customized JPanel with all the components it needs. This way, your classes are self-contained and it will be much more easier to read and maintain.

• Declare your variables into proper scope and access them with getters and setters.