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我正在尝试用 Java 构建一个小型库存应用程序，它根据卡片布局切换视图（或页面）。对于标准更改，用户将使用应用程序顶部的菜单，并且效果很好。

但是，在我的一个屏幕上，用户将输入一个项目 ID 号进行检查。如果在数据库中未找到该 ID 号，应用程序应切换到“新项目”页面。这是我不知所措的地方。我试图更改当前查看的卡片，但似乎没有得到它。

如果这是一个基本问题（以及写得不好的 Java :)），请原谅我，我在编写这个应用程序时正在自学 Java。附上我正在添加部分主类（InventoryTrackingSystem）和 GUI 类（试图更改视图的类）。

/ * ** * * MAIN 类* ** * ** * *** /

package inventorytrackingsystem;
import java.io.*;
import java.net.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.rmi.*;

public class InventoryTrackingSystem implements ItemListener {
  JPanel mainPanel;
  JFrame frame;

  JPanel cards = new JPanel(new CardLayout());; //a panel that uses CardLayout

  final static String MAINPANEL = "Main";
  final static String CHECKITEMSPANEL = "Check Items";
  final static String NEWITEMPANEL = "New Item";
  final static String CHECKOUTITEMPANEL = "Check Out Item";
  final static String ITEMINFOPANEL = "Item Information";
  final static String LISTALLITEMSPANEL = "List All Items";
  JPanel comboBoxPane;
  private JComboBox cb;
  static String comboBoxItems[] = {MAINPANEL,CHECKITEMSPANEL,NEWITEMPANEL,CHECKOUTITEMPANEL,ITEMINFOPANEL,LISTALLITEMSPANEL};

  public static void main(String[] args) {
    InventoryTrackingSystem ITS = new InventoryTrackingSystem();
    /* Use an appropriate Look and Feel */
    try {
      UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
    } catch (UnsupportedLookAndFeelException ex) {
      ex.printStackTrace();
    } catch (IllegalAccessException ex) {
      ex.printStackTrace();
    } catch (InstantiationException ex) {
      ex.printStackTrace();
    } catch (ClassNotFoundException ex) {
      ex.printStackTrace();
    }
    /* Turn off metal's use of bold fonts */
    UIManager.put("swing.boldMetal", Boolean.FALSE);

    //Schedule a job for the event dispatch thread:
    //creating and showing this application's GUI.
//    javax.swing.SwingUtilities.invokeLater(new Runnable() {
//      public void run() {
        ITS.createAndShowGUI();
//      }
//    });

  }

  public void addComponentToPane(Container pane){
    //Put the JComboBox in a JPanel to get a nicer look.
    comboBoxPane = new JPanel(); //use FlowLayout
    cb = new JComboBox(comboBoxItems);
    cb.setEditable(false);
    cb.addItemListener(this);
    comboBoxPane.add(cb);
    cb.setVisible(false);

    //Create the "cards".
    JPanel main = new guiBuilder().buildGui("main");
    JPanel checkItems = new guiBuilder().buildGui("checkItems");
    JPanel newItems = new guiBuilder().buildGui("newItems");
    JPanel checkOutItems = new guiBuilder().buildGui("checkOutItems");
    JPanel itemInfo = new guiBuilder().buildGui("itemInfo");
    JPanel listAllItems = new guiBuilder().buildGui("listAllItems");

    //Create the panel that contains the "cards".
    cards = new JPanel(new CardLayout());
    cards.add(main, MAINPANEL);
    cards.add(checkItems, CHECKITEMSPANEL);
    cards.add(newItems, NEWITEMPANEL);
    cards.add(checkOutItems, CHECKOUTITEMPANEL);
    cards.add(itemInfo, ITEMINFOPANEL);
    cards.add(listAllItems, LISTALLITEMSPANEL);

    pane.add(comboBoxPane, BorderLayout.PAGE_START);
    pane.add(cards, BorderLayout.CENTER);
  }

  public void itemStateChanged(ItemEvent evt) {
    CardLayout cl = (CardLayout)(cards.getLayout());
    cl.show(cards, (String)evt.getItem());
  }

  /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event dispatch thread.
     */
    private void createAndShowGUI() {
      //Create and set up the window.
      frame = new JFrame("Inventory Tracking System");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      frame.setLayout(new BorderLayout());
      Menu m1 = new Menu("Options");

      MenuItem mi1_0 = new MenuItem("Main Page");
        mi1_0.setActionCommand("main");
        mi1_0.addActionListener(new menuListener());

      MenuItem mi1_1 = new MenuItem("Check Item");
        mi1_1.setActionCommand("checkItem");
        mi1_1.addActionListener(new menuListener());
      MenuItem mi1_2 = new MenuItem("Add New Item");
        mi1_2.setActionCommand("addItem");
        mi1_2.addActionListener(new menuListener());
      MenuItem mi1_3 = new MenuItem("List All Items");
        mi1_3.setActionCommand("listAllItems");
        mi1_3.addActionListener(new menuListener());
      MenuItem mi1_4 = new MenuItem("Check Out Item");
        mi1_4.setActionCommand("checkOutItem");
        mi1_4.addActionListener(new menuListener());
      MenuItem mi1_5 = new MenuItem("Exit");
        mi1_5.setActionCommand("exit");
        mi1_5.addActionListener(new menuListener());

      Menu m2 = new Menu("Help");
      MenuItem mi2_0 = new MenuItem("About");
        mi2_0.setActionCommand("about");
        mi2_0.addActionListener(new menuListener());

      m1.add(mi1_0);
      m1.add(mi1_1);
      m1.add(mi1_2);
      m1.add(mi1_3);
      m1.add(mi1_4);
      m1.add(mi1_5);

      m2.add(mi2_0);

      MenuBar mb = new MenuBar();
      frame.setMenuBar(mb);
      mb.add(m1);
      mb.add(m2);

      //Create and set up the content pane.
      //InventoryTrackingSystem setGUI = new InventoryTrackingSystem();
      addComponentToPane(frame.getContentPane());

      //Display the window.
      frame.pack();
      frame.setVisible(true);

      frame.setSize(780, 830);

      frame.addWindowListener(new WindowAdapter(){
        public void windowClosing(WindowEvent we){
          System.exit(0);
        }
        public void windowClosed(WindowEvent we){
          System.exit(0);
        }
      });

    }

    class menuListener implements ActionListener{
      public void actionPerformed(ActionEvent ev){
        String thisAction=ev.getActionCommand();

        if(thisAction.equals("main")){
          cb.setSelectedItem(MAINPANEL);
        }else if(thisAction.equals("checkItem")){
          //change GUI
          cb.setSelectedItem(CHECKITEMSPANEL);
        }else if(thisAction.equals("addItem")){
          //change GUI
          cb.setSelectedItem(NEWITEMPANEL);
        }else if(thisAction.equals("checkOutItem")){
          //change GUI
          cb.setSelectedItem(CHECKOUTITEMPANEL);
        }else if(thisAction.equals("listAllItems")){
          //change GUI
          cb.setSelectedItem(LISTALLITEMSPANEL);
        }else if(thisAction.equals("exit")){
          System.exit(0);
        }else if(thisAction.equals("about")){
          JOptionPane.showMessageDialog(frame, "About This App");
        }
      }
    }

  public void swapView(String s){
    CardLayout cl = (CardLayout)(cards.getLayout());
    cl.show(cards, s);
  }
}

/ * ** * * GUI类* ** * ** * *** /

package inventorytrackingsystem;
import java.io.*;
import java.net.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.Image.*;
import java.awt.image.BufferedImage.*;
import javax.imageio.*;
import com.sun.jimi.core.*;


public class guiBuilder {
  JLabel itemIdLabel;
  JTextField itemID;
  JButton checkIt;
  JButton getSignature;
  mySqlStuff sql=new mySqlStuff();

  public JPanel buildGui(String guiType){
    JPanel thisGUI;
    if(guiType.equals("main")){
      thisGUI=mainGUI();
    }else if(guiType.equals("checkItems")){
      thisGUI=checkItemsGUI();
    }else if(guiType.equals("newItems")){
      thisGUI=newItemsGUI();
    }else if(guiType.equals("checkOutItems")){
      thisGUI=checkOutItemsGUI();
    }else if(guiType.equals("itemInfo")){
      thisGUI=itemInfoGUI();
    }else if(guiType.equals("listAllItems")){
      thisGUI=listAllItemsGUI();
    }else{
      thisGUI=mainGUI();
    }

    return thisGUI;
  } /* close buildGui() Method */

  private JPanel mainGUI(){
    JPanel thisPanel = new JPanel();

    return thisPanel;
  }

  private JPanel checkItemsGUI(){
    JPanel thisPanel = new JPanel();

    JPanel itemSection=new JPanel();
    JPanel exitSection=new JPanel();

    itemIdLabel=new JLabel("Enter/Scan Item ID");
    itemID=new JTextField(4);
    itemID.addKeyListener(new myItemIdListener());

    checkIt=new JButton("Check Item");
    checkIt.addActionListener(new myItemCheckListener());

    itemSection.add(itemIdLabel);
    itemSection.add(itemID);
    itemSection.add(checkIt);

    JButton exitButton=new JButton("Exit");
    exitButton.addActionListener(new exitButtonListener());

    exitSection.add(exitButton);

    thisPanel.add(itemSection);
    thisPanel.add(exitSection);

    return thisPanel;
  }

  private JPanel newItemsGUI(){
    JPanel thisPanel = new JPanel();

    return thisPanel;
  }

  private JPanel checkOutItemsGUI(){
    JPanel thisPanel = new JPanel();

    return thisPanel;
  }

  private JPanel itemInfoGUI(){
    JPanel thisPanel = new JPanel();

    return thisPanel;
  }

  private JPanel listAllItemsGUI(){
    JPanel thisPanel = new JPanel();

    return thisPanel;
  }

  class myItemIdListener implements KeyListener{
    boolean keyGood=false;
    public void keyPressed(KeyEvent keyEvent){
      int keyCode=keyEvent.getKeyCode();
      if((keyCode>=48 && keyCode<=57) || (keyCode>=96 && keyCode<=105)){
        keyGood=true;
      }
    }
    public void keyReleased(KeyEvent keyEvent){
      int keyCode=keyEvent.getKeyCode();
      if((keyCode>=48 && keyCode<=57) || (keyCode>=96 && keyCode<=105)){
        printIt("Released",keyEvent);
      }else if(keyCode==10){
        checkIt.doClick();
      }
    }
    public void keyTyped(KeyEvent keyEvent){
      int keyCode=keyEvent.getKeyCode();
      if((keyCode>=48 && keyCode<=57) || (keyCode>=96 && keyCode<=105)){
        printIt("Typed",keyEvent);
      }
    }
    private void printIt(String title,KeyEvent keyEvent){
      int keyCode=keyEvent.getKeyCode();
      String keyText=KeyEvent.getKeyText(keyCode);
      String currentData;

      if(title.equals("Pressed")){
        keyGood=true;
      }else if(title.equals("Released")){
        System.out.println(title+ " -> "+keyCode+" / "+keyText);
      }else if(title.equals("Typed")){
        System.out.println(title+ " -> "+keyCode+" / "+keyText);
      }

      try{
        String text=itemID.getText();
        if(text.length()==4){
          checkIt.doClick();
        }else{
          System.out.println("currentlLength: "+itemID.getText().length());
        }
      }catch(Exception ex){
        ex.printStackTrace();
      }
    }
  }

/****  THIS IS WHERE THE SWAP VIEW IS CALLED  ****/
  class myItemCheckListener implements ActionListener{
    public void actionPerformed(ActionEvent ev){
      String itemNum=itemID.getText();
      itemID.setText("");
      System.out.println("Checking ID#: "+itemNum);
      ArrayList checkData=new ArrayList(sql.checkInventoryData(itemNum));
      if(checkData.get(0).toString().equals("[NULL]")){
        System.out.println("New Item -> "+checkData.get(0).toString());
        InventoryTrackingSystem ITS = new InventoryTrackingSystem();
        ITS.swapView("NEWITEMPANEL");
      }else{
        System.out.println("Item Exists -> "+checkData.get(0).toString());

      }
      System.out.println(checkData);
    }
  }
  class signaturePadButtonListener implements ActionListener{
    public void actionPerformed(ActionEvent ev){
      signaturePadStuff signature = new signaturePadStuff();
      while(signature.imageFileMoved==false){
        // wait for the signature to be collected and the image moved to the server.
      }
      System.out.println(signature.newFileName);
    }
  }

  class exitButtonListener implements ActionListener{
    public void actionPerformed(ActionEvent ev){
      System.exit(0);
    }
  }

  /** Returns an ImageIcon, or null if the path was invalid. */
  protected ImageIcon createImageIcon(String path, String description) {
    java.net.URL imgURL = getClass().getResource(path);
    if(imgURL != null){
      return new ImageIcon(imgURL, description);
    }else{
      System.err.println("Couldn't find file: " + path);
      return null;
    }
  }

  class submitItemButtonListener implements ActionListener{
    public void actionPerformed(ActionEvent ev){
      String errorMsg = "";
      String[] formResults = new String[25];

    }
  }

  class clearFormButtonListener implements ActionListener{
    public void actionPerformed(ActionEvent ev){
      return;
    }
  }

}
4

1 回答 1

1

在您的 actionPerformed 方法中使用此代码...

InventoryTrackingSystem ITS = new InventoryTrackingSystem();
ITS.swapView("NEWITEMPANEL");

...您正在对 InventoryTrackingSystem 的新实例调用 swapView（这不是您在 main 中创建的实例，并且 UI 显示在屏幕上）。

-编辑-

你需要一个 InventoryTrackingSystem 在你的动作监听器中的实例，你可以例如将它存储在 myItemCheckListener 的成员变量中，如下所示：

class myItemCheckListener implements ActionListener{

    private InventoryTrackingSystem its;

    // constructor takes its instance as argument
    public myItemCheckListener(InventoryTrackingSystem its){
        // ...assigns it to the member variable
        this.its = its;
    }

    public void actionPerformed(ActionEvent ev){
        // call swapView on the correct instance of InventoryTrackingSystem
        its.swapView()
    }
}

当然，由于您的操作侦听器是在 guiBuilder.buildGui() / checkItemsGUI() 中创建的，因此您也需要那里的 ITS 实例。

顺便说一句：没有必要像这样创建新的 guiBuilder 实例：

JPanel main = new guiBuilder().buildGui("main");
...
JPanel listAllItems = new guiBuilder().buildGui("listAllItems");

相反，您可以：

guiBuilder builder = new guiBuilder();
builder.buildGui("main");
builder.build("whatever");
于 2012-01-05T22:45:52.973 回答