Java ListCellRenderer和JList:句柄选择

Question

我被困在一个我必须在学校做的项目上。

我试图为一个“简单”的UI创建一个定制的JList：用例应该显示一个订单列表，并且用户应该能够选择一个并通过按两个按钮(read和done)来设置读/完成，这两个按钮也充当“unsetter”(我使用的是两个布尔值，它们的类顺序一直是t、f、t、f.)。一旦按下“完成”，所选行应变为绿色(并永久保留在该颜色上)，直到“完成”按钮再次按在该行上(=unset)。按钮"Read“的相同之处是，按类顺序将选定的行永久转成黄色，与"is_read”标志有关。

在阅读了一些相关的文章之后，我编写了这个自定义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，一切都会弹出，但是当我选择一行时，我按下这两个按钮中的一个，直到我选择一个新的行:然后继续变绿或变黄(取决于我按的按钮)我选择的行的颜色。

我很确定这是一个与我的自定义单元格渲染器相关的问题，也是因为我还在学习如何使用它，我开始变得非常困惑。

下面是我剩下的与UI相关的代码，也许它很有用。按钮及其侦听器位于一个单独的类(自定义JPanel)中，但它们工作正常，所以.

类InitGraphics (由我的测试类直接调用)：

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

这会害死你的：

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

这根本改变不了什么。我觉得你想：

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

注意，要在这段代码上做任何工作，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;
    }

}

在未来，请为我们做这项工作，因为你是寻求帮助的人，而我们是志愿者。

此外，还包括：

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

千万不要在渲染器里做这种事。这段代码应该放在创建JList的地方，而不是在渲染器中。

这是我最新的SSCCE，其中包括清除/读取/完成按钮

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;
    }

}