java - JTable只显示1行

Question

我试图在 JTable 中显示结果集的一部分(两列)，但我只能看到一行。 JTable 位于现有 GUI 中，结果集被传递给 GUI 类中的方法。 当我执行 Vector size() 时，它返回一个。 这告诉我列表中只有一个条目。我应该看到 4 个条目 我看到的条目是我期望的 4 个条目中的最后一个。

请看下面的方法: 任何帮助将不胜感激。

public static void getResultSet(ResultSet resultSet)  throws SQLException { 

        ResultSetMetaData metaData = resultSet.getMetaData();

                    //JTable name is resultsTable includes Scrollpane


         // names of columns

        Vector<String> columnNames = new Vector<String>();
        int columnCount = 2;
        for (int column = 1; column <= columnCount; column++) {
            columnNames.add(metaData.getColumnName(column));
            System.out.println("ColumnNames "+columnNames );
        }

     // data from the table

      //  Vector<Vector<Object>> data = new Vector<Vector<Object>>();
        Vector<Vector<String>> data = new Vector<Vector<String>>();
        while (resultSet.next()) {
            Vector<String> vector = new Vector<String>();
            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                vector.add(resultSet.getString(columnIndex)); 
            }

            data.add(vector);
            System.out.println("Vector Value = "+ data);
            System.out.println("Vector Size =" + data.size()); //Returning 1 - Should see 4 entries

            DefaultTableModel datamodel = new DefaultTableModel(data,columnNames);
            resultsTable.setModel(datamodel); 


        }

Answer 1

"This is telling me there is only one entry in the list. I should be seeing at 4 entries The entry I am seeing is the last one of what I expect would be 4."

您每次迭代都会创建一个新的 DefaultTableModel。不要这样做。

DefaultTableModel datamodel = new DefaultTableModel(data,columnNames);
resultsTable.setModel(datamodel);

把上面的内容去掉。相反，首先设置模型。然后只需在循环中 .addRow(row)

for (int column = 1; column <= columnCount; column++) {
     columnNames.add(metaData.getColumnName(column));
     System.out.println("ColumnNames "+columnNames );
}
DefaultTableModel datamodel = new DefaultTableModel(columnNames, 0);
table.setModel(datamodel);

while (resultSet.next()) {
    Vector<String> vector = new Vector<String>();
    for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
        vector.add(resultSet.getString(columnIndex)); 
    }
    datamodel.addRow(vector);
}

DefaultTableModel(columnNames, 0) 的构造函数，其中 0 是初始行数。因此，您需要做的就是在 while(rs.next()) 中动态地逐行添加行。对于 Vector 中获得的每一行数据，只需 datamodal.addRow(vector)

<小时/>

更新

就像我说的，我不知道你做错了什么，但我的代码没有任何问题。这是一个测试程序

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.Vector;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class TestTableModel {

    private ResultSet resultSet = null;

    public TestTableModel() throws SQLException {
        initDB();

        JTable table = new JTable(getModel(resultSet));
        JScrollPane scroll = new JScrollPane(table);

        JFrame frame = new JFrame("Test Table Model");
        frame.add(scroll);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    TestTableModel testTableModel = new TestTableModel();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        });
    }

    private DefaultTableModel getModel(ResultSet resultSet) throws SQLException {
        ResultSetMetaData metaData = resultSet.getMetaData();
        int columnCount = metaData.getColumnCount();
        Vector<String> columnNames = new Vector<>();

        for (int column = 1; column <= columnCount; column++) {
            columnNames.add(metaData.getColumnName(column));
            System.out.println("ColumnNames " + columnNames);
        }
        DefaultTableModel dataModel = new DefaultTableModel(columnNames, 0);

        while (resultSet.next()) {
            Vector<String> vector = new Vector<>();
            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                vector.add(resultSet.getString(columnIndex));
            }
            dataModel.addRow(vector);
        }


        return dataModel;
    }

    private void initDB() throws SQLException {
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost/...", "...", "...");
            ps = conn.prepareStatement("SELECT * FROM city");
            resultSet = ps.executeQuery();

        } catch (ClassNotFoundException | SQLException ex) {
            ex.printStackTrace();
        } 

    }
}