如何将JTextfield信息从JDialog传递到JFrame（单独的类）

Question

I have been trying to pass the info of my JTextField that is in a JDialog into my JFrame. Both the JDialog and JFrame are in separate classes. I have tried to store the JTextField into a JLable using the .setText and .getText and then passing the JLable into the JFrame but with no luck.

I know there are many similar questions but I have tried many different approaches but still no luck. I am relatively new to Java and do not know all the in's and out's. Any help is very appreciated!

My code for the JFrame:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JPanel;

public class StockApp extends JFrame implements PropertyChangeListener {

    private JPanel main = new JPanel();
    private JPanel north = new JPanel();
    private JPanel center = new JPanel();
    private JPanel south = new JPanel();
    private JButton buyStock = new JButton("Buy Stock");
    private JButton sellStock = new JButton("Sell Stock");
    public TestTest variables = new TestTest();
    private JLabel stockNameNorth = new JLabel("Stock Name");
    private JLabel stockPriceNorth = new JLabel("Stock Price");
    String stockName = variables.getStockName();
    String stockPrice = variables.getStockPrice();

    public StockApp() {
        setTitle("StockApp");
        getContentPane().setBackground(Color.white);
        setSize(400,400);
        setLocation(500,200);
        setVisible(true);
        main.setLayout(new BorderLayout());
        north.setLayout(new FlowLayout());
        center.setLayout(new FlowLayout());
        south.setLayout(new FlowLayout());
        stockNameNorth.setText(stockName);
        stockPriceNorth.setText(stockPrice);
        add(main);
        north.add(stockNameNorth);
        north.add(stockPriceNorth);
        south.add(buyStock);
        south.add(sellStock);
        main.add(north, BorderLayout.NORTH);
        main.add(center, BorderLayout.CENTER);
        main.add(south, BorderLayout.SOUTH);
    }
}

And Dialog:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class TestTest extends JDialog implements ActionListener {

private JPanel main = new JPanel();
    private JPanel north = new JPanel();
    private JPanel center = new JPanel();
    private  JPanel south = new JPanel();
    private JLabel stockNameLabel = new JLabel("Stock name: ");
    private JLabel stockPriceLabel = new JLabel("Stock price(£): ");
    private JTextField stockNameIn = new JTextField(5);
    private JTextField stockPriceIn = new JTextField(5);
    private JButton buttonOK = new JButton("OK");
    public JLabel stockPrice = new JLabel();
    public JLabel stockName = new JLabel();

    public TestTest() {
        getContentPane().setBackground(Color.white);
        setSize(400,400);
        setLocation(500,200);
        setModal(false);
        setVisible(true);
        getRootPane().setDefaultButton(buttonOK);
        main.setLayout(new BorderLayout());
        north.setLayout(new FlowLayout());
        center.setLayout(new FlowLayout());
        south.setLayout(new FlowLayout());
        add(main);
        north.add(stockNameLabel);
        north.add(stockNameIn);
        center.add(stockPriceLabel);
        center.add(stockPriceIn);
        south.add(buttonOK);
        main.add(north, BorderLayout.NORTH);
        main.add(center, BorderLayout.CENTER);
        main.add(south, BorderLayout.SOUTH);
        buttonOK.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == buttonOK){
            stockName.setText(stockNameIn.getText());
            stockPrice.setText(stockPriceIn.getText());
            dispose();
            new StockApp();
            }
        }
    public String getStockName() {
        return stockNameIn.getText();
    }
    public String getStockPrice() {
        return stockPriceIn.getText();
    }
}    

I am trying to pass the stockName and stockPrice variables from the JDialog into the JFrame. I then want the name and price to display at the top of the JFrame.

Answer 1

For demonstration, what the problem is, we need less Fields and Buttons.

So far, no component of StockApp needs to be accessed from different methods, so there is no need to make them visible outside of the ctor.

More explanations in the code.

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;

public class StockApp extends JFrame {

    public StockApp() {
        // move those unreferenced panels here, so we don't have to reason about them:
        JPanel main = new JPanel();
        JPanel north = new JPanel();
        JPanel center = new JPanel();
        JPanel south = new JPanel();
        // add price later, when name works
        JButton buyStock = new JButton("Buy Stock");
        JLabel stockNameNorth = new JLabel("Stock Name");

        // critical change: Make the label, which you like to update,
        // accessible by whom it should be updated:
        TestTest variables = new TestTest (stockNameNorth);

        setTitle ("StockApp");
        getContentPane().setBackground(Color.white);
        setSize (600,400);
        setLocation (500,200);
        setVisible (true);
        // make the close-frame action terminate the program:
        setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

        main.setLayout (new BorderLayout());
        north.setLayout (new FlowLayout());
        center.setLayout (new FlowLayout());
        south.setLayout (new FlowLayout());
        add (main);
        north.add (stockNameNorth);
        south.add (buyStock);
        main.add (north, BorderLayout.NORTH);
        main.add (center, BorderLayout.CENTER);
        main.add (south, BorderLayout.SOUTH);
    }

    // Main method to start the damn thing
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new StockApp ();
            }
        });
    }
}

// no need to make this class public in a short test:   
class TestTest extends JDialog implements ActionListener {

    // this are elements, visible outside the construction phase,
    // we need to have access to from more than one method.
    // Make this important distinction visible to the reader: 
    JLabel name;
    JTextField stockNameIn = new JTextField (5);
    JButton buttonOK = new JButton ("OK");

    // add the JLabel to update to the ctor, so that it can't be forgotten
   // to be set
    public TestTest (JLabel pname) {
        // we copy the reference to the label, to have access to it in 
        // the actionPerformed method.
        name = pname;
        JPanel main = new JPanel();
        JPanel north = new JPanel();
        JPanel center = new JPanel();
        JPanel south = new JPanel();
        JLabel stockNameLabel = new JLabel ("Stock name: ");
        getContentPane().setBackground(Color.white);
        // different size/location than frame, so that they don't hide
        // each other completly
        setSize (400,600);
        setLocation (700,300);
        setModal (false);
        setVisible (true);
        getRootPane().setDefaultButton(buttonOK);
        main.setLayout (new BorderLayout());
        north.setLayout (new FlowLayout());
        center.setLayout (new FlowLayout());
        south.setLayout (new FlowLayout());
        add (main);
        north.add (stockNameLabel);
        north.add (stockNameIn);
        south.add (buttonOK);
        main.add (north, BorderLayout.NORTH);
        main.add (center, BorderLayout.CENTER);
        main.add (south, BorderLayout.SOUTH);
        buttonOK.addActionListener(this);
    }

    // here we need access to the button - was it the OK-Button, clicked?    
    // and the textfield stockNameIn, to read the text 
    // and the name field from the frame, to set the text 
    public void actionPerformed(ActionEvent e) {
        if (e.getSource () == buttonOK) {
            name.setText (stockNameIn.getText());
            dispose();
        }
    }
}