如何保存和打開文件順序Java GUI

Question

所以我的問題是我的最后一個buttonPanel。 我不知道如何使用GUI保存和打開文件，我可以獲取全部信息，但是可以的幫助。 “用戶應該能夠單擊標簽為“總計”的按鈕，該按鈕在標簽中顯示總購買價格（總計應包括密歇根州6％的銷售稅）。另一個按鈕允許用戶保存訂單以備案。另一個按鈕允許用戶從文件中打開訂單。”

對於“保存”，另外，在提交保存之前，程序應詢問用戶是否確定要保存文件。他們應能夠從此彈出對話框中指示是否要保存文件。用戶指示他們不想保存文件，則不保存訂單；如果他們指示要保存文件，則使用新訂單創建（或覆蓋）文件。訂單文件的名稱為order。文本。”

對於“打開”，您的程序應該能夠打開並保存文件。當程序打開訂單時，所有GUI組件都應設置為反映文件中訂單的適當值。如果是order.txt文件還不存在（即從未保存過訂單），則顯示一個對話框，告訴用戶“沒有可用的保存訂單”，並且主GUI保持不變。

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

public class IcecreamOrdersGUI extends JFrame
{
   private IcecreamFlavorPanel icecreamFlavors;  // iceCreamFlavor panel
   private NutsPanel nuts; //nuts panel
   private SyrupPanel syrup; //syrup panel
   private ScoopsPanel scoops; //scoops panel
   private JPanel buttonPanel; //To hold the buttons
   private JButton saveButton; // To save the order
   private JButton openButton; // to open the order
   private JButton totalButton; //To figure out the total
   private final double TAX_RATE = 0.06; // Sales tax rate

  /**
      Constructor
   */

  public IcecreamOrdersGUI()
  {
         //Display a title.
         setTitle("Icecream Orders");

         //Specify an action for the close button.
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         //Create a BorderLayout manager.
         setLayout(new BorderLayout());
         // Create the custom panels.
         icecreamFlavors = new IcecreamFlavorPanel();
         scoops = new ScoopsPanel();
         nuts = new NutsPanel();
         syrup = new SyrupPanel();

         // Create the button panel.
         buildButtonPanel();

         //Add the components to the content pane.
         add(icecreamFlavors, BorderLayout.WEST);
         add(scoops, BorderLayout.CENTER);
         add(nuts, BorderLayout.NORTH);
         add(syrup, BorderLayout.EAST);
         add(buttonPanel, BorderLayout.SOUTH);

     //Pack the contents of the window and display it.
     pack();
     setVisible(true);
}

private void buildButtonPanel()
{
   //Create a panel for the buttons.
   buttonPanel = new JPanel();

   //Create the buttons.
   saveButton = new JButton("Save Order");
   openButton = new JButton("Open Order");
   totalButton = new JButton("Total");

   //Register the action listeners.
   saveButton.addActionListener(new saveButtonListener());
   openButton.addActionListener(new openButtonListener());
   totalButton.addActionListener(new totalButtonListener());

   //Add the buttons to the button panel.
   buttonPanel.add(saveButton);
   buttonPanel.add(openButton);
   buttonPanel.add(totalButton);
} 
private class totalButtonListener implements ActionListener
{
   public void actionPerformed(ActionEvent e)
   {
      //Variables to hold the subtotal, tax, and total
      double subtotal, tax, total;

      //Calculate the subtotal.
      subtotal = icecreamFlavor.getIcecreamFlavorCost() + nuts.getNutsCost() + syrup.getSyrupCost() + scoops.getScoopsCost();

 // Calculate the sales tax
 tax = subtotal * TAX_RATE;

 // Calcuate the total
 total = subtotal + tax;

 //Create a DecimalFormat object to format output.
 DecimalFormat dollar = new DecimalFormat("0.00");

 //Display the charges.
 JOptionPane.showMessageDialog(null, "Subtotal: $" + 
              dollar.format(subtotal) + "\n" + 
              "Tax: $" + dollar.format(tax) + "\n" +
              "Total: $" + dollar.format(total));
}
}

/**
Private  inner class that handles the event when
the user clicks the Exit button.
*/

private class ExitButtonListener implements ActionListener 
{
public void actionPerformed(ActionEvent e)
{
     System.exit(0);
}

}

/** 
main method
*/
public static void main(String[] args)
   {
     new OrderCalculatorGUI();
    }
}

Answer 1

使用JFileChooser打開/保存文件。 查看用法