java - 如何创建可滚动的 JTable

Question

我真的不知道我做错了什么。我尝试过遵循其他人的代码，但我似乎无法理解如何向我的 JTable 添加滚动条

这是我到目前为止所拥有的:

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JButton;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableColumn;
import javax.swing.table.TableModel;
import javax.swing.JTextArea;
import javax.swing.JTable;
import javax.swing.JTextPane;
import javax.swing.border.BevelBorder;

public class TBB_SQLBuilder {

    private JFrame frame;
    private JTable table;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TBB_SQLBuilder window = new TBB_SQLBuilder();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public TBB_SQLBuilder() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 950, 900);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JTextArea textArea = new JTextArea();

        JButton button = new JButton("New button");

        table = new JTable();

        table.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        new JScrollPane(table, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

        GroupLayout groupLayout = new GroupLayout(frame.getContentPane());
        groupLayout.setHorizontalGroup(
            groupLayout.createParallelGroup(Alignment.TRAILING)
                .addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
                        .addComponent(table, GroupLayout.DEFAULT_SIZE, 938, Short.MAX_VALUE)
                        .addGroup(groupLayout.createSequentialGroup()
                            .addComponent(textArea, GroupLayout.PREFERRED_SIZE, 289, GroupLayout.PREFERRED_SIZE)
                            .addPreferredGap(ComponentPlacement.RELATED)
                            .addComponent(button)))
                    .addContainerGap())
        );
        groupLayout.setVerticalGroup(
            groupLayout.createParallelGroup(Alignment.LEADING)
                .addGroup(groupLayout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
                        .addComponent(textArea, GroupLayout.PREFERRED_SIZE, 77, GroupLayout.PREFERRED_SIZE)
                        .addComponent(button))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addComponent(table, GroupLayout.PREFERRED_SIZE, 176, GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(613, Short.MAX_VALUE))
        );
        frame.getContentPane().setLayout(groupLayout);
        frame.add(new JScrollPane(table));


        button.addActionListener(new ActionListener(){
               public void actionPerformed(ActionEvent ae){
                  String getValue = textArea.getText();
                  String connectDB = "jdbc:ucanaccess:///Users/sebastianzeki/Documents/PhysJava/My.mdb;";
                    Connection conn;
                    try {
                        conn = DriverManager.getConnection(connectDB);
                        Statement st =conn.createStatement();
                        ResultSet rsHNum = st.executeQuery(getValue);

                         table.setModel(buildTableModel(rsHNum));  
                            ((DefaultTableModel)table.getModel()).fireTableDataChanged(); // show changes 

                    } catch (SQLException e) {
                        e.printStackTrace();
                    }                 
               }
            }); 
    }
    public static DefaultTableModel buildTableModel(ResultSet rs1)
            throws SQLException {
        ResultSetMetaData metaData = rs1.getMetaData();

        // names of columns
        Vector<String> columnNames = new Vector<String>();
        int columnCount = metaData.getColumnCount();
        for (int column = 1; column <= columnCount; column++) {
            columnNames.add(metaData.getColumnName(column));
        }

        // data of the table
        Vector<Vector<Object>> data = new Vector<Vector<Object>>();

        while (rs1.next()) {
            Vector<Object> vector = new Vector<Object>();
            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                vector.add(rs1.getObject(columnIndex));

                System.out.println(rs1.getObject(columnIndex));
            }
            data.add(vector);
        }
        return new DefaultTableModel(data, columnNames);
    }

Answer 1

虽然您使用 JScrollPane 来放置表格，但您并没有真正将滚动 Pane 添加到 GroupLayout 中。相反，您将其添加到 JFrame 中 - 这是您的第一个错误。

所以你应该先创建scrollpane，然后在其中添加table；然后将滚动 Pane 添加到GroupLayout，如下所示

JScrollPane scrollPane = new JScrollPane(table);
// Force the scrollbars to always be displayed
scrollPane.setHorizontalScrollBarPolicy(
    JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scrollPane.setVerticalScrollBarPolicy(
    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); 


GroupLayout groupLayout = new GroupLayout(frame.getContentPane());
groupLayout.setHorizontalGroup(
    groupLayout.createParallelGroup(Alignment.TRAILING)
    .addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
      .addContainerGap()
      .addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
        .addComponent(scrollPane, GroupLayout.DEFAULT_SIZE, 938, Short.MAX_VALUE)

因此，无论您在哪里执行addComponent(table)，都应该改为addComponent(scrollPane)。现在，让我们看两行。就在创建滚动 Pane 之后。

scrollPane.setHorizontalScrollBarPolicy(
    JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
scrollPane.setVerticalScrollBarPolicy(
    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); 

这些将为您提供您正在寻找的精美外观。即使没有任何内容可滚动，滚动条(禁用)也是如此。