自定义DefaultTableCellRenderer不会更改jTable上行的背景颜色

Question

我正在尝试使用自定义的DefaultTableCellRenderer从ArrayList填充表并使用它来呈现它：

public class CustomRender extends DefaultTableCellRenderer {
    private ArrayList<Color> desiredColors = new ArrayList<Color>();

    public void setColors(Color incomingColor)
    {
        desiredColors.add(incomingColor);
    }

    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        Component cellComponent = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
        for (int i = 0; i < desiredColors.size(); i++) {
            cellComponent.setBackground(desiredColors.get(i));
        }
        return cellComponent;
    }
}

我用这种方式

CustomRender colouringTable = new CustomRender();

DefaultTableModel model = new DefaultTableModel(){
    public boolean isCellEditable(int rowIndex, int mColIndex) {
        return false;
    }
}; 

table = new JTable(model);
JScrollPane scroller = new JScrollPane(table);

model.addColumn("ID"); 
model.addColumn("Username"); 
model.addColumn("Departement"); 

for (Employee e: Departement.employees) {
    model.addRow(new Object[]{String.valueOf(e.userId), e.username, e.departement});
    if (e.chef) {
        colouringTable.setColors(Color.RED); 
    } else {
        colouringTable.setColors(Color.GREEN); 
    }
}

for (int i = 0; i < table.getColumnCount(); i++) {
    table.getColumnModel().getColumn(i).setCellRenderer(colouringTable);
}

但是由于某种原因，所有行都不是红色或绿色，它没有改变任何颜色。 谁能指出我做错了什么？

Answer 1

您没有正确使用单元格渲染器。 目前，您的代码在填充JTable的模型时，将颜色填充到ArrayList，desireColors中，然后在渲染器中迭代该列表，但是这没有任何意义，因为所有单元格都将仅被赋予其最后保留的颜色。数组列表。

相反，您要做的是为渲染器提供两种颜色，可能是在其构造器中，并且在渲染器的getTableCellRendererComponent方法内，测试表中由value参数获得的数据，并使用该信息设置渲染器的颜色。

例如，

class MyRenderer extends DefaultTableCellRenderer {
    private Color chefColor;
    private Color defaultColor;

    public MyRenderer(Color chefColor, Color defaultColor) {
        this.chefColor = chefColor;
        this.defaultColor = defaultColor;
        setOpaque(true);
    }

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
            boolean hasFocus, int row, int column) {
        Component superComp = super.getTableCellRendererComponent(table, value, isSelected,
                hasFocus, row, column);

        // here test if row holds a chef item
        // if so, set background color to chefColor
        // otherwise set background color to the defaultColor.
        return superComp;
    }
}

---

例如：

import java.awt.Color;
import java.awt.Component;

import javax.swing.*;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;

/**
 * Example of using a DefaultTableModel that holds a row of specific type
 * Example of hidden column determining color of cells
 * @author Pete
 *
 */
@SuppressWarnings("serial")
public class SimpleTableExampe extends JPanel {
    RestaurantEmployee[] employees = {
            new RestaurantEmployee("John", true, 1),
            new RestaurantEmployee("Bill", false, 2),
            new RestaurantEmployee("Sally", true, 3),
            new RestaurantEmployee("Frank", false, 4),
            new RestaurantEmployee("Jim", false, 5),
            new RestaurantEmployee("Imelda", true, 6)
    };
    private MyTableModel tableModel = new MyTableModel();
    private JTable table = new JTable(tableModel);

    public SimpleTableExampe() {
        MyRenderer renderer = new MyRenderer(Color.RED, Color.GREEN);
        for (int i = 0; i < table.getColumnCount(); i++) {
            table.getColumnModel().getColumn(i).setCellRenderer(renderer);
        }
        add(new JScrollPane(table));
        for (RestaurantEmployee employee : employees) {
            tableModel.addEmployee(employee);
        }        
    }

    private static void createAndShowGui() {
        SimpleTableExampe mainPanel = new SimpleTableExampe();

        JFrame frame = new JFrame("SimpleTableExampe");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

class RestaurantEmployee {
    private String name;
    private boolean chef;
    private int id;

    public RestaurantEmployee(String name, boolean chef, int id) {
        this.name = name;
        this.chef = chef;
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public boolean isChef() {
        return chef;
    }

    public int getId() {
        return id;
    }

    @Override
    public String toString() {
        return "RestaurantEmployee [name=" + name + ", chef=" + chef + ", id=" + id + "]";
    }
}

@SuppressWarnings("serial")
class MyTableModel extends DefaultTableModel {
    private static final String[] COLUMN_NAMES = { "Name", "ID" };

    public MyTableModel() {
        super(COLUMN_NAMES, 0);
    }

    public void addEmployee(RestaurantEmployee employee) {
        addRow(new RestaurantEmployee[] { employee });
    }

    @Override
    public int getColumnCount() {
        return COLUMN_NAMES.length;
    }

    @Override
    public Class<?> getColumnClass(int columnIndex) {
        if (getRowCount() > 0) {
            return getValueAt(0, columnIndex).getClass();
        } else {
            return super.getColumnClass(columnIndex);
        }
    }

    public RestaurantEmployee getEmployee(int row) {
        return (RestaurantEmployee) super.getValueAt(row, 0);
    }

    @Override
    public Object getValueAt(int row, int column) {
        RestaurantEmployee employee = (RestaurantEmployee) super.getValueAt(row, 0);
        switch (column) {
        case 0:
            return employee.getName();
        case 1:
            return employee.getId();        
        default:
            return null;
        }
    }

    @Override
    public boolean isCellEditable(int row, int column) {
        return false;
    }

}

@SuppressWarnings("serial")
class MyRenderer extends DefaultTableCellRenderer {
    private static final int ALPHA = 60;
    private Color chefColor;
    private Color defaultColor;

    public MyRenderer(Color chefColor, Color defaultColor) {
        this.chefColor = chefColor;
        this.defaultColor = defaultColor;
        setOpaque(true);
        setHorizontalAlignment(SwingConstants.CENTER);
    }

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,
            boolean hasFocus, int row, int column) {
        Component superComp = super.getTableCellRendererComponent(table, value, isSelected,
                hasFocus, row, column);
        if (value != null) {
            MyTableModel tableModel = (MyTableModel) table.getModel();
            boolean chef = tableModel.getEmployee(row).isChef();
            Color c = chef ? chefColor : defaultColor;
            if (!hasFocus && !isSelected) {
                c = new Color(c.getRed(), c.getGreen(), c.getBlue(), ALPHA);
            } 

            superComp.setBackground(c);
        }
        return superComp;
    }
}