java - JTable 渲染器不会为单元格着色

Question

我已经编写了一个渲染器，但我的程序没有为单元格着色，我不知道为什么。当我尝试为整行着色时，它也只为 7 行中的 3 行着色。有人可以帮我吗？

public void isLow(JTable jTableBestandstabelle) {
    jTableBestandstabelle.setDefaultRenderer(Object.class, new DefaultTableCellRenderer() {
        @Override
        public Component getTableCellRendererComponent(
                JTable aTable, Object aNumberValue, boolean aIsSelected,
                boolean aHasFocus, int aRow, int aColumn
        ) {

            if (aNumberValue == null) {
                return this;
            }
            Component renderer = super.getTableCellRendererComponent(
                    aTable, aNumberValue, aIsSelected, aHasFocus, aRow, aColumn
            );
            int m = (int) jTableBestandstabelle.getValueAt(aRow, 4);
            int a = (int) jTableBestandstabelle.getValueAt(aRow, 5);
            if (a < m && column == 5) {
                renderer.setForeground(Color.black);
                renderer.setBackground(Color.red);
            } else {
                renderer.setForeground(Color.black);
            }
            return this;
        }


    }); 
}

public void isLow(JTable jTableBestandstabelle) {
    jTableBestandstabelle.setDefaultRenderer(Object.class, new DefaultTableCellRenderer() {
        @Override
        public Component getTableCellRendererComponent(
                JTable aTable, Object aNumberValue, boolean aIsSelected,
                boolean aHasFocus, int aRow, int aColumn
        ) {

            if (aNumberValue == null) {
                return this;
            }
            Component renderer = super.getTableCellRendererComponent(
                    aTable, aNumberValue, aIsSelected, aHasFocus, aRow, aColumn
            );
            int m = (int) jTableBestandstabelle.getValueAt(aRow, 4);
            int a = (int) jTableBestandstabelle.getValueAt(aRow, 5);
            if (a < m) {
                renderer.setForeground(Color.black);
                renderer.setBackground(Color.red);
            } else {
                renderer.setForeground(Color.black);
            }
            return this;
        }


    }); 
}

Answer 1

您的代码中有两个问题:

1. 您在表中使用 boolean 列(最后一列)。因此，如果您想在列中显示复选框，则不能使用 DefaultTableCellRenderer

2. 当您使用table.setDefaultRenderer(Object.class, renderer)时，这对于某些原始磁带(例如Boolean.class或Integer)不起作用.class(不知道为什么)。因此，您还需要为这些类设置渲染器(table.setDefaultRenderer(Integer.class, renderer) 和 table.setDefaultRenderer(Boolean.class, renderer))。但由于第 1 点，这不是一个好主意。

这是我的解决方案:

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

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;

/**
 * <code>TestTable</code>.
 */
public class TestTable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new TestTable()::startUp);
    }

    private void startUp() {
        DefaultTableModel model = new DefaultTableModel(0, 7) {
            @Override
            public Class<?> getColumnClass(int columnIndex) {
                if (columnIndex == 6) {
                    return Boolean.class; // last column is boolean
                } else if (columnIndex == 0 && columnIndex > 3) {
                    return Integer.class; // 1, 4, 5 are integers
                }
                return super.getColumnClass(columnIndex);
            }
        };
        model.addRow(new Object[] {1, "Test1", "Test2", "Test3", 6, 5, false});
        model.addRow(new Object[] {1, "Test11", "Test22", "Test33", 4, 5, true});
        JTable table = new JTable(model);
        for (int i = 0; i < table.getColumnCount(); i++) {
            TableColumn col = table.getColumnModel().getColumn(i);
            int modelCol = table.convertColumnIndexToModel(i);
            col.setCellRenderer(new MyCellRenderer(table.getDefaultRenderer(model.getColumnClass(modelCol))));
        }
        JFrame frm = new JFrame("Table test");
        frm.add(new JScrollPane(table));
        frm.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        frm.pack();
        frm.setLocationRelativeTo(null);
        frm.setVisible(true);
    }

    private static class MyCellRenderer implements TableCellRenderer {
        private final TableCellRenderer origin;

        public MyCellRenderer(TableCellRenderer origin) {
            this.origin = origin;
        }

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row,
                int column) {
            Component c = origin.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            int m = (int) table.getValueAt(row, 4);
            int a = (int) table.getValueAt(row, 5);
            if (a < m) {
                c.setForeground(Color.black);
                c.setBackground(Color.red);
            } else {
                c.setForeground(Color.black);
                c.setBackground(Color.white);
            }
            return c;
        }
    }
}