我用 Java 编写了一个小注释器，带有一个基于 Swing 的简单 GUI，但我遇到了一个让我害怕的问题。 问题是:我有一个 jlist 和两个 jbuttons 修改这样的 jlist，这两个按钮具有相同的监听器，但它们的工作方式不同。 它应该像这样工作:一旦您在 jlist 中选择一行，您可以将其标记为 ON TOPIC 或 OFF TOPIC(使用两个按钮)，该行会更改颜色，然后选择下一行，但是；即使选择位于右行(下一行)，它也会突出显示下一行，只是为了“关闭主题”按钮，为什么？
代码如下:
public class TweetsAnnotator {
static Boolean[] annotations = null;
@SuppressWarnings("rawtypes")
static JList jl;
static JButton offbutton = new JButton("OFF Topic");
static JButton onbutton = new JButton("ON Topic");
static String file = "inception_TweetList";
public TweetsAnnotator() {
}
/**
* @param args
* @throws IOException
* @throws FileNotFoundException
* @throws ClassNotFoundException
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
// Read Tweets from file
ObjectInputStream load = new ObjectInputStream(new FileInputStream(file));
ArrayList<String> list = (ArrayList<String>) load.readObject();
load.close();
System.out.println(list.size() + " Tweets read from: " + file);
// Check and read annotations
File fileannot = new File(file + "Annotations");
if (fileannot.exists()) {
System.out.println("esiste, leggo");
ObjectInputStream loadannot = new ObjectInputStream(new FileInputStream(file + "Annotations"));
annotations = (Boolean[]) loadannot.readObject();
loadannot.close();
} else {
System.out.println("non esiste, creo poi leggo");
ObjectOutputStream save = new ObjectOutputStream(new FileOutputStream(file + "Annotations"));
Boolean[] creatannotations = new Boolean[list.size()];
for (int i=0; i<list.size(); i++) {
creatannotations[i] = (Boolean) null;
}
save.writeObject(creatannotations);
save.close();
ObjectInputStream loadannot = new ObjectInputStream(new FileInputStream(file + "Annotations"));
annotations = (Boolean[]) loadannot.readObject();
loadannot.close();
}
System.out.println(annotations.length + " Annotations loaded");
// Buttons
offbutton.setActionCommand("off");
offbutton.addActionListener(new ButtonListener());
offbutton.setEnabled(false);
onbutton.setActionCommand("on");
onbutton.addActionListener(new ButtonListener());
onbutton.setEnabled(false);
// ButtonPanel
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.X_AXIS));
buttonPane.add(onbutton);
buttonPane.add(offbutton);
// JList
jl = new JList((Object[])list.toArray());
jl.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
jl.setLayoutOrientation(JList.VERTICAL);
jl.setVisibleRowCount(-1);
jl.setCellRenderer(new MyCellRenderer());
ListSelectionListener listSelectionListener = new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting() == false) {
if (jl.getSelectedIndex() == -1) {
//No selection, disable buttons.
onbutton.setEnabled(false);
offbutton.setEnabled(false);
} else {
//Selection, enable buttons.
onbutton.setEnabled(true);
offbutton.setEnabled(true);
}
}
}
};
jl.addListSelectionListener(listSelectionListener);
// JScrollPane
JScrollPane listScroller = new JScrollPane(jl);
// JFrame
JFrame frame = new JFrame(file);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setExtendedState(frame.getExtendedState()|JFrame.MAXIMIZED_BOTH);
frame.addWindowListener(new WindowCloseHandler());
// Add and show
frame.getContentPane().add(listScroller, BorderLayout.CENTER);
frame.getContentPane().add(buttonPane, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
private static class MyCellRenderer extends DefaultListCellRenderer {
private static final long serialVersionUID = 1L;
@SuppressWarnings("rawtypes")
public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus ) {
Component c = super.getListCellRendererComponent( list, value, index, isSelected, cellHasFocus );
if ( annotations[index] == null ) {
c.setBackground( Color.white );
}
else if (annotations[index] == true) {
c.setBackground( Color.green );
} else {
c.setBackground( Color.red);
}
return c;
}
}
private static class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
int ind = jl.getSelectedIndex() +1;
if (e.getActionCommand().equals("on")) {
System.out.println("ON");
annotations[jl.getSelectedIndex()] = true;
}
if (e.getActionCommand().equals("off")) {
System.out.println("OFF");
annotations[jl.getSelectedIndex()] = false;
}
jl.clearSelection();
jl.setSelectedIndex(ind);
}
}
private static class WindowCloseHandler extends WindowAdapter {
public void windowClosing(WindowEvent evt) {
ObjectOutputStream save = null;
try {
save = new ObjectOutputStream(new FileOutputStream(file + "Annotations"));
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
save.writeObject(annotations);
} catch (IOException e) {
e.printStackTrace();
}
try {
save.close();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("Saved.");
}
}
}
尽管 jl.requestFocus();工作正常，我尝试了另一件事使其工作:我交换了这两行
buttonPane.add(onbutton);
buttonPane.add(offbutton);
但是，为什么呢？ 抱歉，如果我再问一次，但这真的很奇怪，不是吗？
最佳答案
在你的单元格渲染中，试试这个
if (annotations[index] == null) {
//c.setBackground(Color.white);
} else if (annotations[index] == true) {
c.setBackground(Color.green);
} else {
c.setBackground(Color.red);
}
对于一些“一点”扩展的东西，你也可以尝试
private static class MyCellRenderer extends DefaultListCellRenderer {
private static final long serialVersionUID = 1L;
private static final Border SELECTION_BORDER = new LineBorder(UIManager.getColor("List.selectionBackground"));
private static final Border EMPTY_BORDER = new EmptyBorder(1, 1, 1, 1);
@SuppressWarnings("rawtypes")
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
Component c = super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
setBorder(EMPTY_BORDER);
if (annotations[index] == null) {
if (isSelected) {
setBorder(SELECTION_BORDER);
}
c.setBackground(Color.white);
} else if (annotations[index] == true) {
c.setBackground(Color.green);
} else {
c.setBackground(Color.red);
}
return c;
}
}
基本上，您所做的是更改选择突出显示颜色，隐藏选择。至于为什么你确实得到了一个“似乎”突出显示所选行的绘画伪影，对我来说仍然是一个谜:P
已更新，了解原因
您有时得到的绘制伪影是单元格渲染器的 hasFocus 参数绘制焦点矩形的结果。
现在，如果您想保留现有的单元格渲染器，请在 ActionEvent 中尝试此操作
//jl.clearSelection();
jl.setSelectedIndex(ind);
jl.requestFocus();
据我所知，重绘管理器似乎有点问题。如果我将 jl.repaint() 添加到您现有的代码中(在 setSelectedIndex 调用下)，我可以让它永远不绘制焦点矩形:P
关于java - JList 使用 jbutton 突出显示，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11807210/