意外的 jtable 自定义渲染器行为
Unexpected jtable custom renderer behavior
我的目标是在 Java Swing 中制作一个基本的像素艺术应用程序（我知道这远非理想，我们必须为 class 使用 Swing 做一些事情，我认为这听起来一种乐趣）。
想法是将 JTable 中任何选定单元格的颜色更改为 JComboBox 中选定的颜色。
这是点击突出显示的单元格 (9,7) 后当前的样子：
并且在点击别处（例如显示的 (0,6) 处）后，它往往会填充两个 space 之间的 space，以及行也是如此。
这当然不理想 - 我只想让一个单元格在每次点击时改变颜色。我是自定义 JTable 渲染的新手，所以我附上了必要的代码，希望有人能帮助我发现我的错误。当我创建 CustomModel class.
的 JTable 时，感兴趣的区域朝向底部
//Lots of importing
public class PixelArtistGUI extends JFrame {
String colors[] = { "Red", "Orange", "Yellow", "Green", "Blue", "Magenta", "Black", "White" };
JComboBox colorList = new JComboBox(colors);
public PixelArtistGUI() {
setTitle("PixelArtist");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
this.setPreferredSize(new Dimension(400, 450));
// Content Pane
JPanel contentPane = new JPanel();
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[] { 125, 125, 125 };
gbl_contentPane.rowHeights = new int[] {360, 15};
contentPane.setLayout(gbl_contentPane);
JLabel colorSelect = new JLabel("Select Color:");
colorSelect.setFont(new Font("Tahoma", Font.PLAIN, 18));
colorSelect.setHorizontalAlignment(SwingConstants.CENTER);
GridBagConstraints gbc_colorSelect = new GridBagConstraints();
gbc_colorSelect.insets = new Insets(5, 0, 0, 0);
gbc_colorSelect.gridx = 0;
gbc_colorSelect.anchor = GridBagConstraints.SOUTH;
gbc_colorSelect.fill = GridBagConstraints.BOTH;
gbc_colorSelect.gridy = 1;
contentPane.add(colorSelect, gbc_colorSelect);
GridBagConstraints gbc_colorList = new GridBagConstraints();
gbc_colorList.anchor = GridBagConstraints.SOUTH;
gbc_colorList.fill = GridBagConstraints.BOTH;
gbc_colorList.insets = new Insets(5, 0, 0, 0);
gbc_colorList.gridx = 1;
gbc_colorList.gridy = 1;
contentPane.add(colorList, gbc_colorList);
JButton screenshotButton = new JButton("Save Screenshot");
GridBagConstraints gbc_screenshotButton = new GridBagConstraints();
gbc_screenshotButton.anchor = GridBagConstraints.SOUTH;
gbc_screenshotButton.fill = GridBagConstraints.BOTH;
gbc_screenshotButton.insets = new Insets(5, 0, 0, 0);
gbc_screenshotButton.gridx = 2;
gbc_screenshotButton.gridy = 1;
contentPane.add(screenshotButton, gbc_screenshotButton);
String[] colHeadings = { "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "" };
int numRows = 16;
PixelModel model = new PixelModel(numRows, colHeadings.length);
model.setColumnIdentifiers(colHeadings);
JTable table_1 = new JTable(model);
table_1.setBorder(new LineBorder(new Color(0, 0, 0)));
table_1.setRowSelectionAllowed(false);
table_1.setDefaultRenderer(Object.class, new CustomModel());
GridBagConstraints gbc_table_1 = new GridBagConstraints();
gbc_table_1.gridwidth = 3;
gbc_table_1.fill = GridBagConstraints.BOTH;
gbc_table_1.gridx = 0;
gbc_table_1.gridy = 0;
contentPane.add(table_1, gbc_table_1);
table_1.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
table_1.setCellSelectionEnabled(true);
table_1.setRowHeight(23);
this.pack();
}
// Custom table renderer to change cell colors
public class CustomModel extends DefaultTableCellRenderer {
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
JLabel label = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row,
column);
Color c;
try {
String cString = colorList.getSelectedItem().toString().toLowerCase();
Field field = Class.forName("java.awt.Color").getField(cString);
c = (Color) field.get(null);
} catch (Exception e) {
c = null;
}
if (isSelected)
label.setBackground(c);
return label;
}
}
// Custom table model to make the cells selectable but not editable
public class PixelModel extends DefaultTableModel {
PixelModel(int numRows, int numColumns) {
super(numRows, numColumns);
}
public boolean isCellEditable(int row, int column) {
return false;
}
}
我很感激任何提示，我一直在思考如何解决这个问题。
查看 Concepts: Editors and Renderers, Writing a Custom Cell Renderer and Using Other Editors 以了解有关渲染器和编辑器实际工作方式的更多详细信息。
每次调用getTableCellRendererComponent时，您都需要根据单元格的值和状态完全配置渲染器。所以基本上，您所做的只是简单地设置一次背景颜色，并且永远不会在任何其他情况下更改它，这意味着当任何其他单元格被绘制时（无论出于何种原因），它仍然使用相同的背景颜色。
相反，您应该使用存储在 TableModel 中的值来决定单元格应该绘制什么。为此，您可能需要一个简单的 CellEditor，它可以简单地 return 当前选择的颜色
也许像...
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.lang.reflect.Field;
import java.util.EventObject;
import javax.swing.AbstractCellEditor;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
public class PixelArtistGUI extends JFrame {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
PixelArtistGUI frame = new PixelArtistGUI();
frame.setVisible(true);
}
});
}
String colors[] = {"Red", "Orange", "Yellow", "Green", "Blue", "Magenta", "Black", "White"};
JComboBox colorList = new JComboBox(colors);
public PixelArtistGUI() {
setTitle("PixelArtist");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
this.setPreferredSize(new Dimension(400, 450));
// Content Pane
JPanel contentPane = new JPanel();
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[]{125, 125, 125};
gbl_contentPane.rowHeights = new int[]{360, 15};
contentPane.setLayout(gbl_contentPane);
JLabel colorSelect = new JLabel("Select Color:");
colorSelect.setFont(new Font("Tahoma", Font.PLAIN, 18));
colorSelect.setHorizontalAlignment(SwingConstants.CENTER);
GridBagConstraints gbc_colorSelect = new GridBagConstraints();
gbc_colorSelect.insets = new Insets(5, 0, 0, 0);
gbc_colorSelect.gridx = 0;
gbc_colorSelect.anchor = GridBagConstraints.SOUTH;
gbc_colorSelect.fill = GridBagConstraints.BOTH;
gbc_colorSelect.gridy = 1;
contentPane.add(colorSelect, gbc_colorSelect);
GridBagConstraints gbc_colorList = new GridBagConstraints();
gbc_colorList.anchor = GridBagConstraints.SOUTH;
gbc_colorList.fill = GridBagConstraints.BOTH;
gbc_colorList.insets = new Insets(5, 0, 0, 0);
gbc_colorList.gridx = 1;
gbc_colorList.gridy = 1;
contentPane.add(colorList, gbc_colorList);
JButton screenshotButton = new JButton("Save Screenshot");
GridBagConstraints gbc_screenshotButton = new GridBagConstraints();
gbc_screenshotButton.anchor = GridBagConstraints.SOUTH;
gbc_screenshotButton.fill = GridBagConstraints.BOTH;
gbc_screenshotButton.insets = new Insets(5, 0, 0, 0);
gbc_screenshotButton.gridx = 2;
gbc_screenshotButton.gridy = 1;
contentPane.add(screenshotButton, gbc_screenshotButton);
String[] colHeadings = {"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", ""};
int numRows = 16;
PixelModel model = new PixelModel(numRows, colHeadings.length);
model.setColumnIdentifiers(colHeadings);
JTable table_1 = new JTable(model);
table_1.addFocusListener(new FocusAdapter() {
@Override
public void focusLost(FocusEvent e) {
TableCellEditor editor = table_1.getCellEditor();
if (editor != null) {
if (editor.stopCellEditing()) {
editor.cancelCellEditing();
}
}
}
});
table_1.setBorder(new LineBorder(new Color(0, 0, 0)));
table_1.setRowSelectionAllowed(false);
table_1.setDefaultRenderer(Object.class, new CustomRenderer());
table_1.setDefaultEditor(Object.class, new CustomEditor());
GridBagConstraints gbc_table_1 = new GridBagConstraints();
gbc_table_1.gridwidth = 3;
gbc_table_1.fill = GridBagConstraints.BOTH;
gbc_table_1.gridx = 0;
gbc_table_1.gridy = 0;
contentPane.add(table_1, gbc_table_1);
table_1.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
table_1.setCellSelectionEnabled(true);
table_1.setRowHeight(23);
this.pack();
}
public class CustomRenderer extends DefaultTableCellRenderer {
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
super.getTableCellRendererComponent(table, null, false, hasFocus, row, column);
if (value != null && value instanceof Color) {
setBackground((Color) value);
} else {
setBackground(null);
}
return this;
}
}
public class CustomEditor extends AbstractCellEditor implements TableCellEditor {
private JPanel panel;
public CustomEditor() {
this.panel = new JPanel();
}
@Override
public Object getCellEditorValue() {
Color c = null;
try {
String cString = colorList.getSelectedItem().toString().toLowerCase();
Field field = Class.forName("java.awt.Color").getField(cString);
c = (Color) field.get(null);
} catch (Exception e) {
c = null;
}
return c;
}
@Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
panel.setBackground((Color) getCellEditorValue());
return panel;
}
@Override
public boolean isCellEditable(EventObject e) {
return true;
}
}
// Custom table model to make the cells selectable but not editable
public class PixelModel extends DefaultTableModel {
PixelModel(int numRows, int numColumns) {
super(numRows, numColumns);
}
@Override
public boolean isCellEditable(int row, int column) {
return true;
}
}
}
现在，在任何人扑向我之前。我会用 Color 填充 JComboBox 并使用自定义 ListCellRenderer 来显示它。
我的目标是在 Java Swing 中制作一个基本的像素艺术应用程序（我知道这远非理想，我们必须为 class 使用 Swing 做一些事情，我认为这听起来一种乐趣）。
想法是将 JTable 中任何选定单元格的颜色更改为 JComboBox 中选定的颜色。
这是点击突出显示的单元格 (9,7) 后当前的样子：
并且在点击别处（例如显示的 (0,6) 处）后，它往往会填充两个 space 之间的 space，以及行也是如此。
这当然不理想 - 我只想让一个单元格在每次点击时改变颜色。我是自定义 JTable 渲染的新手，所以我附上了必要的代码，希望有人能帮助我发现我的错误。当我创建 CustomModel class.
的 JTable 时，感兴趣的区域朝向底部//Lots of importing
public class PixelArtistGUI extends JFrame {
String colors[] = { "Red", "Orange", "Yellow", "Green", "Blue", "Magenta", "Black", "White" };
JComboBox colorList = new JComboBox(colors);
public PixelArtistGUI() {
setTitle("PixelArtist");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
this.setPreferredSize(new Dimension(400, 450));
// Content Pane
JPanel contentPane = new JPanel();
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[] { 125, 125, 125 };
gbl_contentPane.rowHeights = new int[] {360, 15};
contentPane.setLayout(gbl_contentPane);
JLabel colorSelect = new JLabel("Select Color:");
colorSelect.setFont(new Font("Tahoma", Font.PLAIN, 18));
colorSelect.setHorizontalAlignment(SwingConstants.CENTER);
GridBagConstraints gbc_colorSelect = new GridBagConstraints();
gbc_colorSelect.insets = new Insets(5, 0, 0, 0);
gbc_colorSelect.gridx = 0;
gbc_colorSelect.anchor = GridBagConstraints.SOUTH;
gbc_colorSelect.fill = GridBagConstraints.BOTH;
gbc_colorSelect.gridy = 1;
contentPane.add(colorSelect, gbc_colorSelect);
GridBagConstraints gbc_colorList = new GridBagConstraints();
gbc_colorList.anchor = GridBagConstraints.SOUTH;
gbc_colorList.fill = GridBagConstraints.BOTH;
gbc_colorList.insets = new Insets(5, 0, 0, 0);
gbc_colorList.gridx = 1;
gbc_colorList.gridy = 1;
contentPane.add(colorList, gbc_colorList);
JButton screenshotButton = new JButton("Save Screenshot");
GridBagConstraints gbc_screenshotButton = new GridBagConstraints();
gbc_screenshotButton.anchor = GridBagConstraints.SOUTH;
gbc_screenshotButton.fill = GridBagConstraints.BOTH;
gbc_screenshotButton.insets = new Insets(5, 0, 0, 0);
gbc_screenshotButton.gridx = 2;
gbc_screenshotButton.gridy = 1;
contentPane.add(screenshotButton, gbc_screenshotButton);
String[] colHeadings = { "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "" };
int numRows = 16;
PixelModel model = new PixelModel(numRows, colHeadings.length);
model.setColumnIdentifiers(colHeadings);
JTable table_1 = new JTable(model);
table_1.setBorder(new LineBorder(new Color(0, 0, 0)));
table_1.setRowSelectionAllowed(false);
table_1.setDefaultRenderer(Object.class, new CustomModel());
GridBagConstraints gbc_table_1 = new GridBagConstraints();
gbc_table_1.gridwidth = 3;
gbc_table_1.fill = GridBagConstraints.BOTH;
gbc_table_1.gridx = 0;
gbc_table_1.gridy = 0;
contentPane.add(table_1, gbc_table_1);
table_1.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
table_1.setCellSelectionEnabled(true);
table_1.setRowHeight(23);
this.pack();
}
// Custom table renderer to change cell colors
public class CustomModel extends DefaultTableCellRenderer {
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
JLabel label = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row,
column);
Color c;
try {
String cString = colorList.getSelectedItem().toString().toLowerCase();
Field field = Class.forName("java.awt.Color").getField(cString);
c = (Color) field.get(null);
} catch (Exception e) {
c = null;
}
if (isSelected)
label.setBackground(c);
return label;
}
}
// Custom table model to make the cells selectable but not editable
public class PixelModel extends DefaultTableModel {
PixelModel(int numRows, int numColumns) {
super(numRows, numColumns);
}
public boolean isCellEditable(int row, int column) {
return false;
}
}
我很感激任何提示，我一直在思考如何解决这个问题。
查看 Concepts: Editors and Renderers, Writing a Custom Cell Renderer and Using Other Editors 以了解有关渲染器和编辑器实际工作方式的更多详细信息。
每次调用getTableCellRendererComponent时，您都需要根据单元格的值和状态完全配置渲染器。所以基本上，您所做的只是简单地设置一次背景颜色，并且永远不会在任何其他情况下更改它，这意味着当任何其他单元格被绘制时（无论出于何种原因），它仍然使用相同的背景颜色。
相反，您应该使用存储在 TableModel 中的值来决定单元格应该绘制什么。为此，您可能需要一个简单的 CellEditor，它可以简单地 return 当前选择的颜色
也许像...
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.lang.reflect.Field;
import java.util.EventObject;
import javax.swing.AbstractCellEditor;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
public class PixelArtistGUI extends JFrame {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
PixelArtistGUI frame = new PixelArtistGUI();
frame.setVisible(true);
}
});
}
String colors[] = {"Red", "Orange", "Yellow", "Green", "Blue", "Magenta", "Black", "White"};
JComboBox colorList = new JComboBox(colors);
public PixelArtistGUI() {
setTitle("PixelArtist");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
this.setPreferredSize(new Dimension(400, 450));
// Content Pane
JPanel contentPane = new JPanel();
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[]{125, 125, 125};
gbl_contentPane.rowHeights = new int[]{360, 15};
contentPane.setLayout(gbl_contentPane);
JLabel colorSelect = new JLabel("Select Color:");
colorSelect.setFont(new Font("Tahoma", Font.PLAIN, 18));
colorSelect.setHorizontalAlignment(SwingConstants.CENTER);
GridBagConstraints gbc_colorSelect = new GridBagConstraints();
gbc_colorSelect.insets = new Insets(5, 0, 0, 0);
gbc_colorSelect.gridx = 0;
gbc_colorSelect.anchor = GridBagConstraints.SOUTH;
gbc_colorSelect.fill = GridBagConstraints.BOTH;
gbc_colorSelect.gridy = 1;
contentPane.add(colorSelect, gbc_colorSelect);
GridBagConstraints gbc_colorList = new GridBagConstraints();
gbc_colorList.anchor = GridBagConstraints.SOUTH;
gbc_colorList.fill = GridBagConstraints.BOTH;
gbc_colorList.insets = new Insets(5, 0, 0, 0);
gbc_colorList.gridx = 1;
gbc_colorList.gridy = 1;
contentPane.add(colorList, gbc_colorList);
JButton screenshotButton = new JButton("Save Screenshot");
GridBagConstraints gbc_screenshotButton = new GridBagConstraints();
gbc_screenshotButton.anchor = GridBagConstraints.SOUTH;
gbc_screenshotButton.fill = GridBagConstraints.BOTH;
gbc_screenshotButton.insets = new Insets(5, 0, 0, 0);
gbc_screenshotButton.gridx = 2;
gbc_screenshotButton.gridy = 1;
contentPane.add(screenshotButton, gbc_screenshotButton);
String[] colHeadings = {"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", ""};
int numRows = 16;
PixelModel model = new PixelModel(numRows, colHeadings.length);
model.setColumnIdentifiers(colHeadings);
JTable table_1 = new JTable(model);
table_1.addFocusListener(new FocusAdapter() {
@Override
public void focusLost(FocusEvent e) {
TableCellEditor editor = table_1.getCellEditor();
if (editor != null) {
if (editor.stopCellEditing()) {
editor.cancelCellEditing();
}
}
}
});
table_1.setBorder(new LineBorder(new Color(0, 0, 0)));
table_1.setRowSelectionAllowed(false);
table_1.setDefaultRenderer(Object.class, new CustomRenderer());
table_1.setDefaultEditor(Object.class, new CustomEditor());
GridBagConstraints gbc_table_1 = new GridBagConstraints();
gbc_table_1.gridwidth = 3;
gbc_table_1.fill = GridBagConstraints.BOTH;
gbc_table_1.gridx = 0;
gbc_table_1.gridy = 0;
contentPane.add(table_1, gbc_table_1);
table_1.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
table_1.setCellSelectionEnabled(true);
table_1.setRowHeight(23);
this.pack();
}
public class CustomRenderer extends DefaultTableCellRenderer {
@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
super.getTableCellRendererComponent(table, null, false, hasFocus, row, column);
if (value != null && value instanceof Color) {
setBackground((Color) value);
} else {
setBackground(null);
}
return this;
}
}
public class CustomEditor extends AbstractCellEditor implements TableCellEditor {
private JPanel panel;
public CustomEditor() {
this.panel = new JPanel();
}
@Override
public Object getCellEditorValue() {
Color c = null;
try {
String cString = colorList.getSelectedItem().toString().toLowerCase();
Field field = Class.forName("java.awt.Color").getField(cString);
c = (Color) field.get(null);
} catch (Exception e) {
c = null;
}
return c;
}
@Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
panel.setBackground((Color) getCellEditorValue());
return panel;
}
@Override
public boolean isCellEditable(EventObject e) {
return true;
}
}
// Custom table model to make the cells selectable but not editable
public class PixelModel extends DefaultTableModel {
PixelModel(int numRows, int numColumns) {
super(numRows, numColumns);
}
@Override
public boolean isCellEditable(int row, int column) {
return true;
}
}
}
现在，在任何人扑向我之前。我会用 Color 填充 JComboBox 并使用自定义 ListCellRenderer 来显示它。