用户界面希望在作为复选框的jTable中创建一列，但在运行时显示为“class java”。lang.Boolean'

Question

我正在尝试创建一个接受SQL查询的Jtable。我在显示数据之前插入了一列，并将其设置为布尔类。当我运行代码而不是显示复选框时，它会显示“ClassJava”。而不是lang.Boolean

我尝试调用isCellEditable（）和getColumnClass（）方法

public static void FillTable(JTable table, String Query){
    try
    {   
        Connection conn = DriverManager.getConnection(databaseTest.main_conn,"root",databaseTest.db_usrPW);
        Statement stat = conn.createStatement();
        ResultSet rs = stat.executeQuery(Query);

      //Define new model
        DefaultTableModel tableModel = new DefaultTableModel();

        //Get MetaData from rs
        ResultSetMetaData metaData = rs.getMetaData();

        //Get number of columns from meta data
        int columnCount = (metaData.getColumnCount()+1);

        //Add Boolean column
        tableModel.addColumn(Boolean.class);
        tableModel.getColumnClass(0);

        //Get all column names from meta data and add columns to table model
        for (int columnIndex = 1; columnIndex < columnCount; columnIndex++){
            tableModel.addColumn(metaData.getColumnLabel(columnIndex));
        }

        //Create array of Objects with size of column count from meta data
        Object[] row = new Object[columnCount];

        //Scroll through result set
        while (rs.next()){
            row[0] = Boolean.class;
            tableModel.addRow(row);
            //Get object from column with specific index of result set to array of objects
            for (int i = 1; i < columnCount; i++){
                row[i] = rs.getObject(i);
                }            
            //Now add row to table model with that array of objects as an argument
            tableModel.addRow(row);
        }
        db_table.setModel(tableModel);
        rs.close();
    }catch(Exception e){
        e.printStackTrace();
    }   
}

Answer 1

正如JavaDocs for ^{}所强调的

Warning: DefaultTableModel returns a column class of Object... If you use DefaultTableModel ... you are strongly encouraged to override getColumnClass to return the appropriate type.

虽然评论与TableRowSorter的使用有关，但它强调了问题的根本原因getColumnClass返回的类型为Object，这意味着它不允许对Boolean等类型使用默认呈现

相反，您将需要创建TableModel的自定义实现（我更喜欢AbstractTableModel，但您仍然可以使用DefaultTableModel）并覆盖getColumnClass并为特定列返回更合适的值，例如

import java.awt.EventQueue;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;

public class Test extends JFrame {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                DefaultTableModel model = new DefaultTableModel() {
                    @Override
                    public Class<?> getColumnClass(int columnIndex) {
                        return Boolean.class;
                    }
                };
                model.addColumn("Pick");

                Random rnd = new Random();
                for (int index = 0; index < 10; index++) {
                    Object[] row = new Object[1];
                    row[0] = rnd.nextBoolean();
                    model.addRow(row);
                }
                JTable table = new JTable(model);

                JFrame frame = new JFrame();
                frame.add(new JScrollPane(table));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}

注意这是一个简单的例子，如果你有多个列，你需要决定每个列返回什么