问题描述
我创建了JComboBox并将其更改为背景和前景色。但是我看不到那里有预期的白灰色垂直线,而且我不知道如何解决。此垂直线也应绘制,但不是。
import javax.swing.*;
import java.awt.*;
import java.util.Arrays;
public class TestComboBox {
private static final String[] ANIMALS = new String[]{"Cat","Mouse","Dog","Elephant","Bird","Goat","Bear"};
private static final Color COMBO_COLOR = new Color(71,81,93);
public static class MessageComboBox extends JComboBox<String> {
public MessageComboBox(DefaultComboBoxModel model) {
super(model);
setFont(new Font("Arial",Font.PLAIN,30));
setPreferredSize(new Dimension(350,50));
setRenderer(new MyRenderer());
}
}
private static class MyRenderer extends DefaultListCellRenderer {
@Override
public Component getListCellRendererComponent(JList list,Object value,int index,boolean isSelected,boolean cellHasFocus) {
JComponent comp = (JComponent) super.getListCellRendererComponent(list,value,index,isSelected,cellHasFocus);
list.setBackground(COMBO_COLOR);
list.setForeground(Color.WHITE);
list.setopaque(false);
return comp;
}
}
public static void main(String[] args) throws Exception {
String nimbus = Arrays.asList(UIManager.getInstalledLookAndFeels())
.stream()
.filter(i -> i.getName().equals("Nimbus"))
.findFirst()
.get()
.getClassName();
UIManager.setLookAndFeel(nimbus);
UIManager.put("ComboBox.forceOpaque",false);
JFrame jf = new JFrame();
jf.setSize(800,400);
jf.setVisible(true);
jf.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
jf.setLocationRelativeto(null);
MessageComboBox comboBox = new MessageComboBox(new DefaultComboBoxModel(ANIMALS));
JPanel panel = new JPanel();
panel.add(comboBox);
jf.add(panel,BorderLayout.norTH);
}
}
也许有人对如何解决这个问题有想法?
解决方法
Nimbus defaults说,默认ComboBox.padding
是Insets(3,3,3)
(请参阅Insets doc)。因此,意外的灰线归因于此填充。由于您要删除正确的填充,因此可以通过在您的第一个UIManager
呼叫中的某处添加以下行来解决问题:
UIManager.put("ComboBox.padding",new Insets(3,0));