class RuleComboBox extends JComboBox {
public RuleComboBox() {
super();
this.setModel(new javax.swing.DefaultComboBoxModel(new String[]{"abc", "defg"}));
((JLabel) this.getRenderer()).setHorizontalAlignment(SwingConstants.CENTER);
}
}
getRenderer()
行将文本对齐到中心。
当我使用ruleComboBox1.setEnabled(false)
和ruleComboBox1.setEditable(true)
时,文字会向左对齐,这是我不想要的。我怎么能阻止这个?
我应该解释一下,当我禁用setEditable(true)
时,我会使用ComboBox
来保留文本的外观。
答案 0 :(得分:1)
JComboBox
的编辑器必须实现ComboBoxEditor
接口。默认实现从BasicComboBoxEditor
扩展,返回JTextField作为编辑器。 JTextField
不支持以文本为中心的概念。
因此,您可以实施自己的ComboBoxEditor
。我建议您只需使用BasicComboBoxEditor
并更改代码即可创建JTextPane
而不是JTextField
。然后,当您创建文本窗格时,您可以使用:
SimpleAttributeSet center = new SimpleAttributeSet();
StyleConstants.setAlignment(center, StyleConstants.ALIGN_CENTER);
StyledDocument doc = textPane.getStyledDocument();
doc.setParagraphAttributes(0, doc.getLength(), center, false);
将导致代码居中。
注意:这不是直接转换。按下ActionListener
键时,JTextField会调用Enter
。 JTextPane不支持此功能(默认是插入新行),因此您需要为JTextPane复制此功能。也就是说,您需要使用Key Bindings
来处理Enter
密钥。因此,您需要将ActionListener包装在自定义Action
中,然后将Enter键绑定到文本窗格。
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.border.Border;
import java.awt.Component;
import java.awt.event.*;
import java.lang.reflect.Method;
//import sun.reflect.misc.MethodUtil;
/**
* A custom editor for editable combo boxes. The editor is implemented as a JTextPane.
*
*/
public class TextPaneComboBoxEditor implements ComboBoxEditor {
protected JTextPane editor;
private Object oldValue;
public TextPaneComboBoxEditor() {
editor = createEditorComponent();
}
public Component getEditorComponent() {
return editor;
}
/**
* Creates the internal editor component. Override this to provide
* a custom implementation.
*
* @return a new editor component
* @since 1.6
*/
protected JTextPane createEditorComponent() {
JTextPane editor = new BorderlessTextPane("",9);
editor.setBorder(null);
SimpleAttributeSet center = new SimpleAttributeSet();
StyleConstants.setAlignment(center, StyleConstants.ALIGN_CENTER);
StyledDocument doc = editor.getStyledDocument();
doc.setParagraphAttributes(0, doc.getLength(), center, false);
return editor;
}
/**
* Sets the item that should be edited.
*
* @param anObject the displayed value of the editor
*/
public void setItem(Object anObject) {
String text;
if ( anObject != null ) {
text = anObject.toString();
if (text == null) {
text = "";
}
oldValue = anObject;
} else {
text = "";
}
// workaround for 4530952
if (! text.equals(editor.getText())) {
editor.setText(text);
}
}
public Object getItem() {
Object newValue = editor.getText();
// This code only works for Strings. The default implementation would
// use reflection to create Object of whatever class was stored in the
// ComboBoxModel. You will need to fix the reflection code if you want
// to support other types of data in the model
/*
if (oldValue != null && !(oldValue instanceof String)) {
// The original value is not a string. Should return the value in it's
// original type.
if (newValue.equals(oldValue.toString())) {
return oldValue;
} else {
// Must take the value from the editor and get the value and cast it to the new type.
Class<?> cls = oldValue.getClass();
try {
Method method = MethodUtil.getMethod(cls, "valueOf", new Class[]{String.class});
newValue = MethodUtil.invoke(method, oldValue, new Object[] { editor.getText()});
} catch (Exception ex) {
// Fail silently and return the newValue (a String object)
}
}
}
*/
return newValue;
}
public void selectAll() {
editor.selectAll();
editor.requestFocus();
}
public void addActionListener(ActionListener l) {
// editor.addActionListener(l);
Action enter = new WrappedActionListener(l);
editor.getActionMap().put("insert-break", enter);
}
public void removeActionListener(ActionListener l) {
// editor.removeActionListener(l);
}
static class BorderlessTextPane extends JTextPane {
public BorderlessTextPane(String value,int n) {
// super(value,n);
setText(value);
}
// workaround for 4530952
public void setText(String s) {
if (getText().equals(s)) {
return;
}
super.setText(s);
}
public void setBorder(Border b) {
if (!(b instanceof UIResource)) {
super.setBorder(b);
}
}
}
/**
* A subclass of TextPaneComboBoxEditor that implements UIResource.
* TextPaneComboBoxEditor doesn't implement UIResource
* directly so that applications can safely override the
* cellRenderer property with TextPaneListCellRenderer subclasses.
* <p>
* <strong>Warning:</strong>
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeans™
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*/
public static class UIResource extends TextPaneComboBoxEditor
implements javax.swing.plaf.UIResource {
}
static class WrappedActionListener extends AbstractAction
{
private ActionListener listener;
public WrappedActionListener(ActionListener listener)
{
this.listener = listener;
}
@Override
public void actionPerformed(ActionEvent e)
{
listener.actionPerformed(e);
}
}
}
您当前代码中所需的只是:
comboBox.setEditor( new TextPaneComboBoxEditor() );