JFrame将按钮点击变量传递给另一个类

Question

假设我有两个类，如下所示。在我的第一个类Product中，我有产品实例变量，而在第二个类中，我有我的JFrame组件。现在我试图从JTextField titemName获取值，并在点击按钮时将其赋值给setProductName？

有人请给我一个关于如何做的提示吗？到现在为止，我得到getWineName的null calue，因为setWineName超出了范围，我猜？

第一类：

public class Wine { 
    private String wineName; 
    private double winePrice; 
    private int wineQnty; 

public Wine(String wineName, double winePrice, int wineQnty) 
{ 
    this.wineName = wineName; 
    this.winePrice = winePrice; 
    this.wineQnty = wineQnty; 
} 

public Wine() 
{ 
    this ("", 0, 0); 
} 


// Getters (accessor methods) and setters(modifier methods) 
public String getWineName() { 
    return wineName; 
} 

public void setWineName(String wineName) { 
    this.wineName = wineName; 
} 

public double getWinePrice() { 
    return winePrice; 
} 

public void setWinePrice(double winePrice) { 
    this.winePrice = winePrice; 
} 

public int getWineQnty() { 
    return wineQnty; 
} 

public void setWineQnty(int wineQnty) { 
    this.wineQnty = wineQnty; 
} 

} 

二等：

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


public class LWMGUI extends JFrame 
implements ActionListener 
{ 
    private Wine wine; 
    private CustomerAccount custAcct; 
    private JButton psale, preturn; 
    private JLabel litemName, litemQuantity, litemPrice, ltransAmount, lcurrBalance; 
    private JTextField titemName, titemQuantity, titemPrice, ttransAmount, tcurrBalance; 

public LWMGUI(Wine w, CustomerAccount c) 
{ 
    wine = w; 
    custAcct = c; 


    // Creating Dialog box to get customer's name 
    String custName = JOptionPane.showInputDialog("Please enter the customer name: "); 
    if (custName.isEmpty() || custName == null){ 
     System.exit(0); 
    } 


    //Creating dialog box to get the current balance for the given customer 
    String currBalanceTxt; 
    while (true){ 
     currBalanceTxt = JOptionPane.showInputDialog("Please enter the current balance for this customer: "); 

     try { 
       Double currBalance = Double.parseDouble(currBalanceTxt); 
       break; 

      } catch (NumberFormatException ex) 
      { 
       JOptionPane.showMessageDialog(null, "Please enter a numeric value!", "Non-numeric value error", JOptionPane.ERROR_MESSAGE); 
      } 
    } 
    Double currBalance = Double.parseDouble(currBalanceTxt); 

    //Setting customer account values 
    c.setAccountName(custName); 
    c.setCurrBalance(currBalance); 

    setTitle("Lilybank Wine Merchants: " + custAcct.getAccountName()); 
    setSize(560, 150); 
    setLocation(200, 200); 

    createTop(); 
    createButtons(); 
    createBottom(); 

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    setVisible(true); 


} 

    private void createTop() { 
     litemName = new JLabel("Name:"); 
     litemQuantity = new JLabel("Quantity:"); 
     litemPrice = new JLabel("Price: £"); 

     titemName = new JTextField(15); 
     titemName.addActionListener(this); 
     titemQuantity = new JTextField(6); 
     titemQuantity.addActionListener(this); 
     titemPrice = new JTextField(7); 
     titemPrice.addActionListener(this); 

     JPanel topPan = new JPanel(); 
     topPan.add(litemName); 
     topPan.add(titemName); 
     topPan.add(litemQuantity); 
     topPan.add(titemQuantity); 
     topPan.add(litemPrice); 
     topPan.add(titemPrice); 
     add(topPan, "North"); 
    } 

    private void createBottom() { 
     ltransAmount = new JLabel("Amount of Transaction:"); 
     lcurrBalance = new JLabel("Current balance:"); 
     ttransAmount = new JTextField(6); 
     tcurrBalance = new JTextField(6); 
     ttransAmount.setEnabled(false); 
     tcurrBalance.setEnabled(false); 

     JPanel lowerPan = new JPanel(); 
     lowerPan.add(ltransAmount); 
     lowerPan.add(ttransAmount); 
     lowerPan.add(lcurrBalance); 
     lowerPan.add(tcurrBalance); 
     add(lowerPan, "South"); 
    } 

    private void createButtons() { 
     // Setting up buttons 
     psale = new JButton("Process Sale"); 
     preturn = new JButton("Process Return"); 
     psale.addActionListener(this); 
     preturn.addActionListener(this); 
     JPanel buttonPan = new JPanel(); 
     buttonPan.add(psale); 
     buttonPan.add(preturn); 
     add(buttonPan, "Center"); 
    } 


    private class saleButton implements ActionListener { 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      // TODO Auto-generated method stub 

     } 

    } 

    public void actionPerformed(ActionEvent e) 
    { 

     if (e.getSource() == psale) 
     { 

      Wine w = wine; 
      CustomerAccount ct = custAcct; 

      System.out.println("Sale button pressed!"); 
      String wName = titemName.getText(); 
      int wQnty = Integer.parseInt(titemQuantity.getText()); 
      Double wPrice = Double.parseDouble(titemPrice.getText()); 

      w.setWineName(wName); 
      w.setWineQnty(wQnty); 
      w.setWinePrice(wPrice); 

      String saleAmount = Double.toString(ct.sale()); 
      System.out.println(saleAmount); 
      ttransAmount.setText(saleAmount); 


     } 

    } 

} 

第三类：

import javax.swing.JFrame; 

公共类MainCl {

public static void main(String[] arg) 
{ 
    Wine wine = new Wine(); 
    CustomerAccount cuAcct = new CustomerAccount(); 
    LWMGUI g = new LWMGUI(wine, cuAcct); 

    System.out.println(wine.getWineName()); 
    System.out.println(wine.getWinePrice()); 
} 

}

Answer 1

您应该在actionPerformed方法中用Product p = product;替代Product p = new Product();行。

Answer 2

Shrotly只是试图在葡萄酒课上工作，您必须更改您的代码，并在主类中删除'wine.get ....'，因为葡萄酒类是空的或现在不工作！你需要打印从动作监听器方法（工作时）的价格或名称如下：

public void actionPerformed(ActionEvent e) 
    { 

     if (e.getSource() == psale) 
     { 

      Wine w = wine; 


      System.out.println("Sale button pressed!"); 
      String wName = titemName.getText(); 
      int wQnty = Integer.parseInt(titemQuantity.getText()); 
      Double wPrice = Double.parseDouble(titemPrice.getText()); 

      w.setWineName(wName); 
      w.setWineQnty(wQnty); 
      w.setWinePrice(wPrice); 

      System.out.println("Name of wine : "+ wName +", "+"Quanty : "+ wQnty +", "+"Price : "+ wPrice); 


     } 

    } 

} 

我希望这帮助you.Good运气