Question

我正在尝试制作链接的ComboBoxes。例如，我有三个组合框，每个组合框都有三个项目（a，b，c）。在第一个组合框的开始时，选择“a”，第二个“b”和第三个“c”。我需要为他们制作这样的ActionListener，这样就可以了：如果将第二个列表中的选择从“b”更改为“a”，则在第一个列表中所选项目会自动从“a”更改为“b” ”

我试图以这种方式解决问题：

 public class MyComboBoxListener implements ActionListener {

        public void actionPerformed(ActionEvent a) {
            int i = 0;
            int j = 0;
            while (a.getSource() != valsListArray.get(i)) {
                i++;
            }
            String selected = valsListArray.get(i).getSelectedItem().toString();
            while (selected != valsListArray.get(j).getSelectedItem() && j != i) {
                j++;
            }
            String r = chosenVals[i];// in the beginnig elements are that order a, b, c
            valsListArray.get(j).setSelectedItem(chosenVals[i]);
            chosenVals[j] = r;
            chosenVals[i] = selected;
        }
    }

但它没有解决问题。

Answer 1

例如

（只有两个链接的JComboBox，其余是/由你决定，我删除了第三个代码.JCombobox故意）

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

public class ComboBoxTwo extends JFrame implements ActionListener, ItemListener {

    private static final long serialVersionUID = 1L;
    private JComboBox mainComboBox;
    private JComboBox subComboBox;
    private Hashtable<Object, Object> subItems = new Hashtable<Object, Object>();

    public ComboBoxTwo() {
        String[] items = {"Select Item", "Color", "Shape", "Fruit"};
        mainComboBox = new JComboBox(items);
        mainComboBox.addActionListener(this);
        mainComboBox.addItemListener(this);
        //prevent action events from being fired when the up/down arrow keys are used
        //mainComboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
        getContentPane().add(mainComboBox, BorderLayout.WEST);
        subComboBox = new JComboBox();//  Create sub combo box with multiple models
        subComboBox.setPrototypeDisplayValue("XXXXXXXXXX"); // JDK1.4
        subComboBox.addItemListener(this);
        getContentPane().add(subComboBox, BorderLayout.EAST);
        String[] subItems1 = {"Select Color", "Red", "Blue", "Green"};
        subItems.put(items[1], subItems1);
        String[] subItems2 = {"Select Shape", "Circle", "Square", "Triangle"};
        subItems.put(items[2], subItems2);
        String[] subItems3 = {"Select Fruit", "Apple", "Orange", "Banana"};
        subItems.put(items[3], subItems3);
//      mainComboBox.setSelectedIndex(1);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String item = (String) mainComboBox.getSelectedItem();
        Object o = subItems.get(item);
        if (o == null) {
            subComboBox.setModel(new DefaultComboBoxModel());
        } else {
            subComboBox.setModel(new DefaultComboBoxModel((String[]) o));
        }
    }

    @Override
    public void itemStateChanged(ItemEvent e) {
        if (e.getStateChange() == ItemEvent.SELECTED) {
            if (e.getSource() == mainComboBox) {
                if (mainComboBox.getSelectedIndex() != 0) {
                    FirstDialog firstDialog = new FirstDialog(ComboBoxTwo.this,
                            mainComboBox.getSelectedItem().toString(), "Please wait,  Searching for ..... ");
                }
            } 
        }
    }

    private class FirstDialog extends JDialog {

        private static final long serialVersionUID = 1L;

        FirstDialog(final Frame parent, String winTitle, String msgString) {
            super(parent, winTitle);
            setModalityType(Dialog.ModalityType.APPLICATION_MODAL);
            JLabel myLabel = new JLabel(msgString);
            JButton bNext = new JButton("Stop Processes");
            add(myLabel, BorderLayout.CENTER);
            add(bNext, BorderLayout.SOUTH);
            bNext.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent evt) {
                    setVisible(false);
                }
            });
            javax.swing.Timer t = new javax.swing.Timer(1000, new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    setVisible(false);
                }
            });
            t.setRepeats(false);
            t.start();
            setLocationRelativeTo(parent);
            setSize(new Dimension(400, 100));
            setVisible(true);
        }
    }

    public static void main(String[] args) {
        JFrame frame = new ComboBoxTwo();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Answer 2

你的问题很有趣。一种解决方案是扩展JComboBox，使其保存对其先前选择的项和索引的引用，这将允许您在需要时提取信息。例如：

import javax.swing.ComboBoxModel;
import javax.swing.JComboBox;

public class NewComboBox extends JComboBox {
   private Object previousSelectedItem = null;
   private int previousSelectedIndex = -1;

   public Object getPreviousSelectedItem() {
      return previousSelectedItem;
   }

   public int getPreviousSelectedIndex() {
      return previousSelectedIndex;
   }

   NewComboBox(ComboBoxModel aModel) {
      super(aModel);
   }

   @Override
   public void setSelectedIndex(int anIndex) {
      previousSelectedIndex = getSelectedIndex();
      previousSelectedItem = getSelectedItem();
      super.setSelectedIndex(anIndex);
   }

   @Override
   public void setSelectedItem(Object anObject) {
      previousSelectedIndex = getSelectedIndex();
      previousSelectedItem = getSelectedItem();
      super.setSelectedItem(anObject);
   }

}

然后你可以根据需要使用它。例如，

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

public class LinkedCombos extends JPanel {
   public static final String[] DATA = {"a", "b", "c"};
   public static final int COMBO_COUNT = 3;
   private DefaultComboBoxModel[] comboModels = new DefaultComboBoxModel[COMBO_COUNT];
   private NewComboBox[] comboBoxes = new NewComboBox[COMBO_COUNT];
   private MyComboListener myComboListener = new MyComboListener();

   public LinkedCombos() {
      for (int i = 0; i < comboModels.length; i++) {
         comboModels[i] = new DefaultComboBoxModel(DATA);
         comboBoxes[i] = new NewComboBox(comboModels[i]);
         comboBoxes[i].setSelectedIndex(i);
         comboBoxes[i].addActionListener(myComboListener);
         add(comboBoxes[i]);
      }
   }

   private class MyComboListener implements ActionListener {
      @Override
      public void actionPerformed(ActionEvent evt) {
         NewComboBox combo = (NewComboBox) evt.getSource();
         String selection = combo.getSelectedItem().toString();

         for (int i = 0; i < comboBoxes.length; i++) {
            NewComboBox comboI = comboBoxes[i];
            if (comboI != combo && comboI.getSelectedItem().equals(selection)) {
               comboI.setSelectedItem(combo.getPreviousSelectedItem());
            }
         }
      }
   }

   private static void createAndShowGui() {
      LinkedCombos mainPanel = new LinkedCombos();

      JFrame frame = new JFrame("LinkedCombos");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

链接的组合框

2 个答案: