[英]Java. How to paint a specific cell in a JTable?
好的,我處於這種情況下...我的班級中有渲染器,但不知道如何使用它來使特定單元格的背景變為紅色。 這是一個房間出租應用程序,我將Jtable用作日歷,因此我希望將油漆單元出租為紅色。 因此,它應該以某種方式采用特定的列和行並使該單元格變為紅色。 我的渲染器在下面,但是正如我所說,自從Java新手以來,我就不知道如何使用它。 真正的問題是如何傳遞該列和行,我對此有疑問。 單元格渲染與其他一些代碼一起工作,但這不是我所需要的。
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;
}
}
好吧,哇,我可能很難解決這個問題。 但是也許以某種方式。 您說您不知道我的代碼看起來如何,我有一些基本的渲染器。 要記住的一件事是,我有一個二維數組ReservedOne,它保存所占用房間的行索引和列索引以及房間號日期,保留時間。 因此,現在在查看示例時,我有點困惑如何使用我的數組設置顏色。 我希望我不會精神崩潰
您的TableModel
應該對此數據建模,這非常重要,因為它允許其余的API圍繞它進行旋轉
真正的問題是如何傳遞該列和行,我對此有疑問。 單元格渲染與其他一些代碼一起工作,但這不是我所需要的。
這就是為什么讓TableModel
包裝數據非常重要的原因,因為表API會將row
和column
信息傳遞給TableCellRenderer
,但還將傳遞單元格值!
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);
}
}
}
這意味着我們現在可以設置單元格渲染器以顯示所需的信息
公共靜態類RoomTableCellRenderer擴展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;
}
}
別忘了,如果要讓表格使用渲染器,則需要注冊它。
table.setDefaultRenderer(Room.class, new RoomTableCellRenderer());
根據可用數據將其存儲在2D String
數組中(您真的不喜歡我)。
這有點臟。 實際上,應該將數據建立在可以傳遞給TableModel
並讓它處理細節。 您還將要謹慎地更新數組,因為在強制您刷新表之前,更新將不會反映在表中……這將不是很漂亮。
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,這使您可以將預訂信息傳遞給TableCellRenderer
,正如我已經指出的那樣,這並不是您應該真正執行的操作,但是它需要對代碼進行大量的重組才能使其正常工作。
現在,我創建一個TableModel
,它基本上采用年和月的值,並為每個單元格返回LocalDate
(如果該單元格超出月份范圍,則返回null
)
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;
}
}
這意味着TableCellRenderer
傳遞LocalDate
值的null
值,並使用此信息,然后您需要在數組中搜索指定日期的任何可能的預訂。
這將令人難以置信地擴展,這就是為什么我避免這樣做並一直試圖讓您更改數據管理方式的原因,但這就是為什么
最后是一個非常粗糙的例子...
該示例並不真正關心您將要管理的所有信息,而僅關心月和日信息
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);
}
});
}
}
您必須為JTable的每一列設置單元格渲染器。 我希望這個例子可以為您提供幫助:
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;
public class JTableTest
{
public static void main( String[] args )
{
SwingUtilities.invokeLater( new Runnable()
{
@Override
public void run()
{
buildUI();
}
} );
}
public static void buildUI()
{
final int w = 500;
final int h = 200;
Object colNames[] =
{
"COL1", "COL2", "COL3"
};
Object[][] data =
{
};
DefaultTableModel dtm = new DefaultTableModel( data, colNames );
dtm.addRow( new Object[]
{
"a", "b", "c"
} );
dtm.addRow( new Object[]
{
"d", "e", "f"
} );
dtm.addRow( new Object[]
{
"g", "h", "i"
} );
dtm.addRow( new Object[]
{
"l", "m", "n"
} );
final JTable t = new JTable( dtm );
final TableColour tce = new TableColour();
t.getColumnModel().getColumn( 0 ).setCellRenderer( tce );
t.getColumnModel().getColumn( 1 ).setCellRenderer( tce );
t.getColumnModel().getColumn( 2 ).setCellRenderer( tce );
final JFrame f = new JFrame();
f.setBounds( 0, 0, w, h );
JScrollPane sp = new JScrollPane( t );
f.getContentPane().add( sp );
f.setVisible( true );
}
}
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;
}
}
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