嗨我正在为航班预订系统制作一个gui,我必须确保用户在点击查询按钮时只在JList中选择一个航班,所以我决定按如下方式制作RadioButton的JList:
flightsList = new JList<JRadioButton>();
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
//user inputs
String takeoff = (String) from.getSelectedItem();
String destina = (String) to.getSelectedItem();
String flyDate = (String) date.getText();
try {
//get all available flights
Flight[] flights = manager.getFlights(takeoff, destina, flyDate);
//model for list
DefaultListModel<JRadioButton> model =
new DefaultListModel<JRadioButton>();
//fill model with flights found
for(int flightNum = 0; flightNum < flights.length; flightNum++) {
model.addElement(new JRadioButton(flights[flightNum].toString()));
}//for
//put model into jlist
flightsList.setModel(model);
} catch (BadQueryException bqe) {
JRadioButton[] errorMessage = {
new JRadioButton("Error: " + bqe.getMessage()) };
//put error message into list
flightsList.setListData(errorMessage);
}//try catch
}//actionPerformed
});
当我运行时,JList显示以下行:
javax.swing.JRadioButton[,0,0,0x0,invalid,alignmentX=0.0,alignmentY=0.5,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@78092fac,flags=296,maximumSize=,minimumSize=,preferredSize=,defaultIcon=,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=2,left=2,bottom=2,right=2],paintBorder=false,paintFocus=true,pressedIcon=,rolloverEnabled=true,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=BA002 | London >> Manchester | Tue, 01/10/2019 06:30]
我可以知道发生了什么以及如何解决这个问题吗? 谢谢。
当我运行时,JList显示以下行:
javax.swing.JRadioButton[,0,0,0x0,invalid,alignmentX=0.0,alignmentY=0.5....
]我可以知道发生了什么以及如何解决这个问题吗?
发生这种情况是因为你的JList
有一个DefaultListCellRenderer.正如你所看到的,这个类extends
JLabel
。方法DefaultListCellRenderer#getListCellRendererComponent()
正在争论Object value
。此值的类型等于JList
的类型。
话虽如此,你的JList
有JRadioButton
作为通用类型(JList< JRadioButton>
),这意味着对象值arguemnt是JRadioButton
。
现在,DefaultListCellRenderer
为了得到它的文本,它调用值的toString()
方法,因此你在列表的单元格中得到这种文本。 (JRadioButton的toString()
方法,返回其细节,坐标,大小等......)
解决方案:
这将是使用自定义ListCellRenderer。这样,您可以在getListCellRendererComponent()
方法中呈现名为“value”i的参数的任何value-property。在您的情况下,您需要渲染JRadioButton
。
我将与代码内部的注释共享一个示例,以便更好地理解这一点。
import java.awt.BorderLayout;
import java.awt.Component;
import java.util.List;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JRadioButton;
import javax.swing.ListCellRenderer;
import javax.swing.SwingUtilities;
public class JListJRadioButtonRenderer extends JFrame {
public JListJRadioButtonRenderer() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addList();
setSize(300, 300);
setLocationRelativeTo(null);
}
private void addList() {
JList<JRadioButton> list = new JList<>();
DefaultListModel<JRadioButton> model = new DefaultListModel<>();
// Add the custom renderer.
list.setCellRenderer(new ListCellRenderer<JRadioButton>() {
@Override
public Component getListCellRendererComponent(JList<? extends JRadioButton> list, JRadioButton value,
int index, boolean isSelected, boolean cellHasFocus) {
// Fix background for selected cells.
value.setBackground(isSelected ? list.getSelectionBackground() : null);
// Select the JRadioButton too since it is selected in the list.
value.setSelected(isSelected);
return value;
}
});
list.setModel(model);
JRadioButton stackButton = new JRadioButton("Hello Stack");
JRadioButton overButton = new JRadioButton("Hello Over");
JRadioButton flowButton = new JRadioButton("Hello Flow");
model.addElement(stackButton);
model.addElement(overButton);
model.addElement(flowButton);
getContentPane().add(list);
JButton printSelected = new JButton("Print selected");
printSelected.addActionListener(e -> {
List<JRadioButton> selectedButtons = list.getSelectedValuesList();
for (JRadioButton r : selectedButtons)
System.out.println(r.getText());
});
getContentPane().add(printSelected, BorderLayout.PAGE_END);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new JListJRadioButtonRenderer().setVisible(true));
}
}
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