Java ListCellRenderer 和 JList：处理选择

Question

我在学校做的一个项目卡住了。

我正在尝试为 "simple" UI 创建自定义 JList：用例应该显示订单列表并且用户应该能够 select 一个并通过按两个按钮（读取和完成）设置 if read/done 这也充当 "unsetters" （我在 class Order 中使用 2 boolean 继续通过 t,f ,t,f...)。按下完成后，selected 行应变为绿色（并永久保持该颜色），直到再次按下该行上的 "Done" 按钮（=未设置）。与按钮 "Read" 相同，它应该将 selected 行永久变为黄色，与 class 订单中的 "is_read" 标志相关。

看了一些相关的帖子，写下了这个习惯ListCellRenderer:

public class CookListCellRender extends JLabel implements ListCellRenderer<Order>{

public CookListCellRender(){
    setOpaque(true);
}

@Override
public Component getListCellRendererComponent(JList<? extends Order> list, Order value, int index, boolean isSelected, boolean cellHasFocus) {

    setLayout(new FlowLayout());
    setText(value.getNameEl());
    list.setVisibleRowCount(30);
    list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    setFont(new Font("Arial",Font.ITALIC,17));

    if (isSelected) {
        setBackground(Color.BLUE);
        setForeground(Color.BLUE);
    } else {
        setBackground(getBackground());
        setForeground(getForeground());
    }

    if(value.getOrderRead()){
        setBackground(Color.YELLOW);
    }else{
        setBackground(Color.WHITE);
    }

    if(value.getOrderDone()){
        setBackground(Color.GREEN);
    }else{
        setBackground(Color.WHITE);
    }
    return this;
}

}

我的问题是，一旦运行我的测试文件，所有内容都会正常弹出，但是当我连续 select 并按下这两个按钮之一时，没有任何反应，直到我 select一个新行：然后不断变成绿色或黄色（取决于我按下的按钮）我正在 selecting 的行的颜色。

我很确定这是与我的自定义单元格渲染器相关的问题，也是因为我仍在学习如何使用它并且开始变得很困惑。

这是我剩下的与UI相关的相关代码，也许有用。按钮及其侦听器位于单独的 class（自定义 JPanel）中，但它们工作正常，所以...

Class InitGraphics（我测试直接调用class）：

public class InitGraphics {

Cook c;
JList list;

public InitGraphics(Cook cuoco){
    c=cuoco;
    initUi();
  }

private void initUi() {
    JFrame frame = new JFrame("Cucina");
    list =new JList(c.getOrdersCopy().toArray());
    list.setCellRenderer(new CookListCellRender());
    JScrollPane panel = new JScrollPane(list);
    panel.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
    panel.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
    ButtonPanel buttonPanel = new ButtonPanel(c.getOrdersCopy(),list);
    buttonPanel.setLayout(new FlowLayout());
    frame.add(buttonPanel,BorderLayout.NORTH);
    frame.add(panel,BorderLayout.CENTER);
    frame.setVisible(true);
    frame.setSize(600, 400);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
  }
}

Answer 1

这要了你的命：

    } else {
        setBackground(getBackground());
        setForeground(getForeground());
    }

它根本没有改变任何东西。我想你想要：

    } else {
        setBackground(null);
        setForeground(null);
    }

请注意，要在此代码上做任何工作，我必须创建自己的 SSCCE:

import java.awt.*;
import javax.swing.*;

public class InitGraphics {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            final DefaultListModel<Order> orderModel = new DefaultListModel<>();
            orderModel.addElement(new Order("One"));
            orderModel.addElement(new Order("Two"));
            orderModel.addElement(new Order("Three"));
            orderModel.addElement(new Order("Four"));
            orderModel.addElement(new Order("Five"));

            JList<Order> orderList = new JList<>(orderModel);
            orderList.setCellRenderer(new CookListCellRender());

            JPanel panel = new JPanel();
            panel.add(new JScrollPane(orderList));

            JOptionPane.showMessageDialog(null, panel);
        });
    }
}

class CookListCellRender extends JLabel implements ListCellRenderer<Order> {

    public CookListCellRender() {
        setOpaque(true);
    }

    @Override
    public Component getListCellRendererComponent(JList<? extends Order> list, Order value, int index,
            boolean isSelected, boolean cellHasFocus) {

        setLayout(new FlowLayout());
        setText(value.getNameEl());
        list.setVisibleRowCount(30);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        setFont(new Font("Arial", Font.ITALIC, 17));

        if (isSelected) {
            setBackground(Color.BLUE);
            setForeground(Color.BLUE);
        } else {
            // TODO: fix!
            // setBackground(getBackground());
            // setForeground(getForeground());
            setBackground(null);
            setForeground(null);
        }

        if (value.getOrderRead()) {
            setBackground(Color.YELLOW);
        } else {
            setBackground(Color.WHITE);
        }

        if (value.getOrderDone()) {
            setBackground(Color.GREEN);
        } else {
            setBackground(Color.WHITE);
        }
        return this;
    }

}

class Order {

    private String nameE1;
    private boolean orderDone;
    private boolean orderRead;

    public Order(String nameE1) {
        this.nameE1 = nameE1;
    }

    public String getNameEl() {
        return nameE1;
    }

    public boolean getOrderDone() {
        return orderDone;
    }

    public boolean getOrderRead() {
        return orderRead;
    }

    public void setOrderDone(boolean orderDone) {
        this.orderDone = orderDone;
    }

    public void setOrderRead(boolean orderRead) {
        this.orderRead = orderRead;
    }

}

以后请为我们代劳，因为你是在寻求帮助，而我们是志愿者。

还有这个：

    list.setVisibleRowCount(30);
    list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

切勿在渲染器中执行此类操作。这段代码应该在您创建 JList 的地方，而不是在渲染器中。

这是我最新的 SSCCE，其中包含 clear/read/done 个按钮

import java.awt.Color;
import java.awt.Component;
import java.awt.Font;
import java.awt.event.*;
import java.util.List;

import javax.swing.*;

public class InitGraphics {
    @SuppressWarnings("serial")
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            final DefaultListModel<Order> orderModel = new DefaultListModel<>();
            orderModel.addElement(new Order("One"));
            orderModel.addElement(new Order("Two"));
            orderModel.addElement(new Order("Three"));
            orderModel.addElement(new Order("Four"));
            orderModel.addElement(new Order("Five"));

            final JList<Order> orderList = new JList<>(orderModel);
            orderList.setCellRenderer(new CookListCellRender());
            orderList.setVisibleRowCount(5);

            JPanel panel = new JPanel();
            // panel.setLayout(new BoxLayout(panel, BoxLayout.LINE_AXIS));
            panel.add(new JScrollPane(orderList));

            panel.add(new JButton(new AbstractAction("Read") {

                @Override
                public void actionPerformed(ActionEvent e) {
                    List<Order> selectedOrders = orderList.getSelectedValuesList();
                    for (Order order : selectedOrders) {
                        order.setOrderRead(true);
                    }
                    orderList.repaint();
                }
            }));
            panel.add(new JButton(new AbstractAction("Done") {

                @Override
                public void actionPerformed(ActionEvent e) {
                    List<Order> selectedOrders = orderList.getSelectedValuesList();
                    for (Order order : selectedOrders) {
                        order.setOrderDone(true);
                    }
                    orderList.repaint();
                }
            }));
            panel.add(new JButton(new AbstractAction("Clear") {

                @Override
                public void actionPerformed(ActionEvent e) {

                    for (int i = 0; i < orderModel.size(); i++) {
                        orderModel.getElementAt(i).setOrderDone(false);
                        orderModel.getElementAt(i).setOrderRead(false);
                    }
                    orderList.repaint();
                }
            }));


            JFrame frame = new JFrame("Test List");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(panel);
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        });
    }
}

@SuppressWarnings("serial")
class CookListCellRender extends JLabel implements ListCellRenderer<Order> {

    public CookListCellRender() {
        setOpaque(true);
    }

    @Override
    public Component getListCellRendererComponent(JList<? extends Order> list, Order value, int index,
            boolean isSelected, boolean cellHasFocus) {

        // setOpaque(true); // !! 

        // !! setLayout(new FlowLayout());
        setText(value.getNameEl());
        // !! list.setVisibleRowCount(30);
        // !! list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        setFont(new Font("Arial", Font.ITALIC, 17));

        if (isSelected) {
            setBackground(Color.BLUE);
            setForeground(Color.BLUE);
        } else {
            // TODO: fix!
            // setBackground(getBackground());
            // setForeground(getForeground());
            setBackground(null);
            setForeground(null);
        }

        if (value.getOrderRead()) {
            setBackground(Color.YELLOW);
        } else {
            setBackground(Color.WHITE);
        }

        if (value.getOrderDone()) {
            setBackground(Color.GREEN);
        } else {
            setBackground(Color.WHITE);
        }
        return this;
    }

}

class Order {

    private String nameE1;
    private boolean orderDone;
    private boolean orderRead;

    public Order(String nameE1) {
        this.nameE1 = nameE1;
    }

    public String getNameEl() {
        return nameE1;
    }

    public boolean getOrderDone() {
        return orderDone;
    }

    public boolean getOrderRead() {
        return orderRead;
    }

    public void setOrderDone(boolean orderDone) {
        this.orderDone = orderDone;
    }

    public void setOrderRead(boolean orderRead) {
        this.orderRead = orderRead;
    }

}

Java ListCellRenderer 和 JList：处理选择

Java ListCellRenderer and JList: handle selection

java

swing

jlist

listcellrenderer