Java 为满足特定语句的JList元素设置前景
我总是遇到Java 为满足特定语句的JList元素设置前景,java,swing,jlist,listcellrenderer,Java,Swing,Jlist,Listcellrenderer,我总是遇到JLists和他们的渲染器的问题。我有一个类Result,它有一个字段:private double sum 我还创建了一个JList,其中包含Result类的实例: model = new DefaultListModel<Result>(); list = new JList<>(model); 建议: 让渲染器扩展DefaultListCellRenderer 重写getListCellRenderComponent方法 进行更改后,返回super.g
JLists
和他们的渲染器的问题。我有一个类Result
,它有一个字段:private double sum代码>
我还创建了一个JList
,其中包含Result
类的实例:
model = new DefaultListModel<Result>();
list = new JList<>(model);
建议:
- 让渲染器扩展DefaultListCellRenderer
- 重写
getListCellRenderComponent
方法
- 进行更改后,返回
super.getListCellRenderComponent(…)
例如,在我的一个项目中,我有:
@SuppressWarnings("serial")
class MyLabPanelListCellRenderer extends DefaultListCellRenderer {
@Override
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {
if (value == null) {
value = "";
} else {
value = ((LabPanel) value).getLabPanelDisplayName();
}
return super.getListCellRendererComponent(list, value, index, isSelected,
cellHasFocus);
}
}
或更完整的示例:
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.util.Random;
import javax.swing.*;
@SuppressWarnings("serial")
public class TestListRenderer extends JPanel {
private static final int TOTAL_ITEMS = 100;
private static final int MAX_VALUE = 15;
private static final int VISIBLE_ROW_COUNT = 15;
private DefaultListModel<Integer> listModel = new DefaultListModel<>();
private JList<Integer> myList = new JList<>(listModel);
private Random random = new Random();
public TestListRenderer() {
for (int i = 0; i < TOTAL_ITEMS; i++) {
listModel.addElement(random.nextInt(MAX_VALUE));
}
myList.setCellRenderer(new MyListCellRenderer());
myList.setVisibleRowCount(VISIBLE_ROW_COUNT);
add(new JScrollPane(myList));
}
private class MyListCellRenderer extends DefaultListCellRenderer {
private static final int PREF_W = 50;
private static final int MAX_INT_VALUE = 10;
private final Color HIGH_VALUE_FG = Color.white;
private final Color HIGH_VALUE_BG = Color.red;
@Override
public Dimension getPreferredSize() {
Dimension superSize = super.getPreferredSize();
return new Dimension(PREF_W, superSize.height);
}
@Override
public Component getListCellRendererComponent(JList<?> list,
Object value, int index, boolean isSelected, boolean cellHasFocus) {
Component superRenderer = super.getListCellRendererComponent(list, value, index, isSelected,
cellHasFocus);
setBackground(null);
setForeground(null);
if (value != null && ((Integer) value).intValue() > MAX_INT_VALUE) {
setBackground(HIGH_VALUE_BG);
setForeground(HIGH_VALUE_FG);
}
return superRenderer;
}
}
private static void createAndShowGui() {
TestListRenderer mainPanel = new TestListRenderer();
JFrame frame = new JFrame("TestListRenderer");
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();
}
});
}
}
导入java.awt.Color;
导入java.awt.Component;
导入java.awt.Dimension;
导入java.util.Random;
导入javax.swing.*;
@抑制警告(“串行”)
公共类TestListRenderer扩展了JPanel{
私有静态最终整数合计项目=100;
专用静态最终int最大值=15;
私有静态最终int可见行计数=15;
private DefaultListModel listModel=新的DefaultListModel();
私有JList myList=新JList(列表模型);
私有随机=新随机();
公共TestListRenderer(){
对于(int i=0;iMAX\u INT\u值){
立根点(高_值_BG);
设置前景(高值前景);
}
返回超级渲染器;
}
}
私有静态void createAndShowGui(){
TestListRenderer主面板=新建TestListRenderer();
JFrame=newJFrame(“TestListRenderer”);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(主面板);
frame.pack();
frame.setLocationByPlatform(真);
frame.setVisible(true);
}
公共静态void main(字符串[]args){
SwingUtilities.invokeLater(新的Runnable(){
公开募捐{
createAndShowGui();
}
});
}
}
如果>10,则以红色背景显示JList中的数字
我建议您使用DefaultListCellRenderer
并覆盖其GetListCellRenderComponent
方法,在该返回super.GetListCellRenderComponent()
中进行自定义。我为您提供了一个字符串
的渲染器示例,请为您的应用程序修改它:
private static ListCellRenderer<? super String> getCellRenderer() {
return new DefaultListCellRenderer(){
@Override
public Component getListCellRendererComponent(JList<?> list,Object value, int index, boolean isSelected,boolean cellHasFocus) {
Component listCellRendererComponent = super.getListCellRendererComponent(list, value, index, isSelected,cellHasFocus);
if(value.toString().length()>1){
listCellRendererComponent.setBackground(Color.RED);
} else {
listCellRendererComponent.setBackground(list.getBackground());
}
return listCellRendererComponent;
}
};
}
private static listcellrenderer要更快地获得更好的帮助,请发布一个。“但它以灾难告终,不值得一提”如果你需要我的帮助,这是值得一提的。你的代码复制错误了吗<代码>如果(结果,getSuma()…
???如果不返回arg0
,则返回渲染组件。为什么不扩展默认渲染器?@HovercraftFullOfEels我也尝试扩展DefaultListCellRenderer
,但不知道应该覆盖哪个方法以及如何参数化它。就像我说的,我对JList和JTables rendere有问题很长一段时间以来,我一直在抱怨。
private static ListCellRenderer<? super String> getCellRenderer() {
return new DefaultListCellRenderer(){
@Override
public Component getListCellRendererComponent(JList<?> list,Object value, int index, boolean isSelected,boolean cellHasFocus) {
Component listCellRendererComponent = super.getListCellRendererComponent(list, value, index, isSelected,cellHasFocus);
if(value.toString().length()>1){
listCellRendererComponent.setBackground(Color.RED);
} else {
listCellRendererComponent.setBackground(list.getBackground());
}
return listCellRendererComponent;
}
};
}