editorcombobox.java

java swing 开发代码

// EditorComboBox.java
// A CellEditor JComboBox subclass for use with Trees (and possibly tables).
// This version will work with any list of values passed as an Object[].
//

package	jswing.ch17;

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

public class EditorComboBox extends JComboBox implements CellEditor {

  String value;
  Vector listeners = new Vector();

  // Mimic all the constructors people expect with ComboBoxes.
  public EditorComboBox(Object[] list) { 
    super(list); 
    setEditable(false);
    value = list[0].toString();

    // Listen to our own action events so that we know when to stop editing.
    addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ae) {
        if (stopCellEditing()) {
          fireEditingStopped();
        }
      }
    });
  }

  // Implement the CellEditor methods.
  public void cancelCellEditing() { }

  // Stop editing only if the user entered a valid value.
  public boolean stopCellEditing() {
    try {
      value = (String)getSelectedItem();
      if (value == null) { value = (String)getItemAt(0); }
      return true;
    }
    catch (Exception e) {
      // Something went wrong.
      return false;
    }
  }

  public Object getCellEditorValue() {
    return value; 
  }

  // Start editing when the right mouse button is clicked.
  public boolean isCellEditable(EventObject eo) {
    if ((eo == null) || 
        ((eo instanceof MouseEvent) && (((MouseEvent)eo).isMetaDown()))) {
      return true;
    }
    return false;
  }

  public boolean shouldSelectCell(EventObject eo) { return true; }

  // Add support for listeners.
  public void addCellEditorListener(CellEditorListener cel) {
    listeners.addElement(cel);
  }

  public void removeCellEditorListener(CellEditorListener cel) {
    listeners.removeElement(cel);
  }

  protected void fireEditingStopped() {
    if (listeners.size() > 0) {
      ChangeEvent ce = new ChangeEvent(this);
      for (int i = listeners.size() - 1; i >= 0; i--) {
        ((CellEditorListener)listeners.elementAt(i)).editingStopped(ce);
      }
    }
  }
}