好吧，我处于这种情况...我的类(class)中有渲染器，但不知道如何使用它使某些单元格的背景变成红色。这是一个房间租赁应用程序，我有 Jtable 作为日历，所以我想要将租赁的单元格涂成红色。所以它应该以某种方式采用特定的列和行并使该单元格变为红色。我的渲染器在下面，但正如我所说，不知道如何使用它，因为我是 java 新手。真正的问题是我如何传递该列和行，我对此有疑问。渲染的单元格可以与其他一些代码一起使用，但这不是我需要的。
ublic class TableColour extends javax.swing.table.DefaultTableCellRenderer {
@Override
public java.awt.Component getTableCellRendererComponent(javax.swing.JTable table, java.lang.Object value, boolean isSelected, boolean hasFocus, int row, int column) {
java.awt.Component cellComponent = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
cellComponent.setBackground(java.awt.Color.RED);
return cellComponent;
}
}
最佳答案
Alright oh wow I might have some trouble figuring this out. But maybe somehow. You said you dont know how my code looks, well I have some basic renderer. One thing to have in mind I have 2 dimensional array ReservedOne which holds row index and column index of taken room also room number date, time until which its reserved. So now Im a bit confused when looking at your example how to use my array to set colors. I hope I wont have mental breakdown
您的 TableModel 应该对这些数据进行建模，这非常重要，因为它允许 API 的其余部分围绕它展开
Real question how do I pass that column and row, I have problem with that. Cell rendered worked with some other code but that wasnt what I need.
这就是为什么让 TableModel 包装数据很重要，因为表 API 会将 row 和 column 信息传递给TableCellRenderer，但它也会传递单元格值!
public class RoomTableModel extends AbstractTableModel {
private Room[][] reservations;
public RoomTableModel(Room[][] reservations) {
this.reservations = reservations;
}
@Override
public int getRowCount() {
return reservations.length;
}
@Override
public int getColumnCount() {
return reservations[0].length;
}
@Override
public Object getValueAt(int rowIndex, int columnIndex) {
return reservations[rowIndex][columnIndex];
}
@Override
public Class<?> getColumnClass(int columnIndex) {
return Room.class;
}
@Override
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
if (aValue instanceof Room) {
Room room = (Room) aValue;
reservations[rowIndex][columnIndex] = room;
fireTableCellUpdated(rowIndex, columnIndex);
}
}
}
这意味着我们现在可以设置单元格渲染器来显示我们需要的信息
公共(public)静态类 RoomTableCellRenderer 扩展了 DefaultTableCellRenderer {
private static Color BOOKED_COLOR = Color.RED;
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
if (value instanceof Room && value != null) {
if (isSelected) {
setBackground(table.getSelectionBackground());
setForeground(table.getSelectionForeground());
} else {
setBackground(table.getBackground());
setForeground(table.getForeground());
}
// Update the details based on the room properties
} else { //if (value == null) {
setBackground(BOOKED_COLOR);
setText(null);
}
return this;
}
}
不要忘记，如果您希望表格使用您的渲染器，您需要注册它...
table.setDefaultRenderer(Room.class, new RoomTableCellRenderer());
已更新...
基于存储在二维 String 数组中的可用数据(你真的不喜欢我)。
这有点脏。实际上，数据应该以可以传递到 TableModel 并让它处理细节的方式设置。您还必须小心更新数组的方式，因为只有在您可以强制刷新表之前，表才会反射(reflect)更新......这不会很漂亮。
public class LocalDateTableCellRenderer extends DefaultTableCellRenderer {
protected static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd");
private String[][] bookings;
public LocalDateTableCellRenderer(String[][] bookings) {
this.bookings = bookings;
}
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
setBackground(isSelected ? table.getSelectionBackground() : table.getBackground());
setForeground(isSelected ? table.getSelectionForeground() : table.getForeground());
if (value instanceof LocalDate) {
LocalDate date = (LocalDate) value;
if (hasBookingFor(date)) {
setForeground(Color.WHITE);
setBackground(Color.RED);
}
setText(formatter.format(date));
} else {
setText(null);
}
return this;
}
protected boolean hasBookingFor(LocalDate date) {
for (String[] data : bookings) {
int day = Integer.parseInt(data[2]);
int month = Integer.parseInt(data[3]);
int year = 2017; // Because :P
LocalDate booking = LocalDate.of(year, month, day);
if (booking.isEqual(date)) {
return true;
}
}
return false;
}
}
基本上，这允许您将预订信息传递给 TableCellRenderer，正如我所说，这不是您真正应该这样做的方式，但它需要对您的代码使其正常工作。
现在，我创建一个 TableModel，它基本上采用年份和月份值，并为每个单元格返回一个 LocalDate(如果是，则返回 null)单元格超出月份范围)
public class CalendarModel extends AbstractTableModel {
public static String[] COLUMN_NAMES = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
private int rows = 0;
private LocalDate startOfCalendar;
private LocalDate firstDayOfMonth;
private LocalDate lastDayOfMonth;
public CalendarModel(int year, Month month) {
firstDayOfMonth = LocalDate.of(year, month, 1);
startOfCalendar = firstDayOfMonth.minusDays(firstDayOfMonth.getDayOfWeek().getValue());
lastDayOfMonth = firstDayOfMonth.with(TemporalAdjusters.lastDayOfMonth());
System.out.println(startOfCalendar.getDayOfWeek());
System.out.println(firstDayOfMonth);
System.out.println(lastDayOfMonth);
Duration between = Duration.between(startOfCalendar.atStartOfDay(), lastDayOfMonth.atStartOfDay());
long days = between.toDays();
rows = (int) Math.round(days / 7d) + 1;
}
@Override
public int getRowCount() {
return rows;
}
@Override
public int getColumnCount() {
return 7;
}
@Override
public Class<?> getColumnClass(int columnIndex) {
return LocalDate.class;
}
@Override
public String getColumnName(int column) {
return COLUMN_NAMES[column];
}
@Override
public Object getValueAt(int rowIndex, int columnIndex) {
LocalDate date = null;
if (startOfCalendar != null) {
int day = (rowIndex * 7) + columnIndex;
date = startOfCalendar.plusDays(day);
if (date.isBefore(firstDayOfMonth) || date.isAfter(lastDayOfMonth)) {
date = null;
}
}
return date;
}
}
这意味着 TableCellRenderer 被传递了 null 值或 LocalDate 值，使用此信息，您需要搜索您的用于指定日期的任何可能预订的数组。
这会严重扩展，这就是为什么我避免这样做并一直试图让您改变管理数据的方式，但事实就是这样
最后是一个非常粗略的例子......
此示例并不真正关心您将管理的所有信息，它只关心月份和日期信息
import java.awt.Color;
import java.awt.Component;
import java.awt.EventQueue;
import java.time.Duration;
import java.time.LocalDate;
import java.time.Month;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjusters;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableModel;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
String[][] bookings = new String[7][6];
bookings[0][2] = "5";
bookings[0][3] = "4";
bookings[1][2] = "10";
bookings[1][3] = "4";
bookings[2][2] = "15";
bookings[2][3] = "4";
bookings[3][2] = "20";
bookings[3][3] = "4";
bookings[4][2] = "25";
bookings[4][3] = "4";
bookings[5][2] = "30";
bookings[5][3] = "4";
bookings[6][2] = "5";
bookings[6][3] = "5";
TableModel model = new CalendarModel(2017, Month.APRIL);
JTable table = new JTable(model);
table.setDefaultRenderer(LocalDate.class, new LocalDateTableCellRenderer(bookings));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JScrollPane(table));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
关于 java 。如何绘制 JTable 中的特定单元格？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43349420/