java - 如何将 ResultSet 响应传递给 JOptionPane showMessageDialog

Question

Oracle“如何创建对话”tutorial没有帮助我，也没有我见过的任何其他帖子，因为它们没有解决将值传递给 showMessageDialog 的问题..

我有一个如下所示的 Java Swing 应用程序:

用户在三个字段中输入信息，当用户按下“获取推文”按钮时，这些字段将合并到 MySQL 查询中。

按下按钮后，我想将行数返回到 showMessageDialog，为用户提供是否继续的选项。

问题:我无法弄清楚如何将 ResultSet 值传递给 showMessageDialog。我需要在 JOptionPane 上设置操作监听器吗？如果是这样，您如何管理时间？

我的 showMessageDialog 如下所示。如您所见，“0”值不正确。

我的 JButton 和关联操作监听器的代码片段:

JButton btnFetch = new JButton("Fetch Tweets!");
    btnFetch.setBackground(new Color(255, 153, 51));
    btnFetch.setForeground(new Color(0, 0, 128));
    btnFetch.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e) {

            app.Query_Variable = queryText.getText();
            app.Start_Date = startText.getText();
            app.End_Date = endText.getText();

            try {
                app.getTweetCount();
            } catch (InstantiationException | IllegalAccessException | ClassNotFoundException | SQLException e2) {
                // TODO Auto-generated catch block
                e2.printStackTrace();
            }

            response = new ResponseOption(app.Tweet_Count);

            /*
            try {
                app.runApplication();

            } catch (InstantiationException | IllegalAccessException
                    | ClassNotFoundException | ParseException
                    | SQLException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }*/

            JOptionPane.showMessageDialog(frame, "Find your file at " + app.Printed_Filename);                  
        }
    });

我为 showMessageDialog 创建了一个名为“ResponseOption”的类，认为这是初始化对话框所必需的。但是，显示的对话框不包含 ResultSet 值...

public class ResponseOption {       
    int RowCount;       
    Object[] options = {"Yes, Please.", 
                        "No, Thanks."};     
    String question = "There are " + RowCount + " Tweets. Do you want to print them?";      
    int n = JOptionPane.showOptionDialog(frame,
            "There are " + X + " Tweets. Do you want to print them?",
            "Question",
            JOptionPane.YES_NO_OPTION,
            JOptionPane.QUESTION_MESSAGE,       
            null,                               // do not use custom icon
            options,                            // titles of buttons
            options[0]);                        // default button title


    public ResponseOption(int Rowcount) {           
        this.RowCount = RowCount;
    }       
}

getTweetCount() 代码: --- 这段代码很好。

public int getTweetCount() throws InstantiationException, IllegalAccessException, ClassNotFoundException, SQLException {

    // create a mysql database connection
    String myDriver = "com.mysql.jdbc.Driver";
    String myUrl = "jdbc:mysql://localhost:3306/?";
    Class.forName(myDriver).newInstance();
    Connection conn = DriverManager.getConnection(myUrl, User, Password);
    PreparedStatement setNames = conn.prepareStatement("SET NAMES 'utf8mb4'");
    setNames.execute();

    // fetch tweet count
    String CountSQL = "SELECT count(*) "
                    + "FROM test.tweet "
                    + "WHERE text LIKE '%" + Query_Variable + "%' "
                    + "AND created_at BETWEEN '" + Start_Date + "' AND '" + End_Date + "';";

    PreparedStatement CountPS = conn.prepareStatement(CountSQL);
    ResultSet CountRS = CountPS.executeQuery();

    if (CountRS.next()) {           
        Tweet_Count = CountRS.getInt(1);
    }

    System.out.println("Tweet count = " + Tweet_Count);     
    return Tweet_Count;     
}

Answer 1

一个可能的改进是更改 ResponseOption，以便在创建对象时不调用 JOptionPane，而是在可用推文计数的构造函数中调用 JOptionPane:

public ResponseOption(int rowCount, JFrame frame) {

    this.rowCount = rowCount;
    String question = "There are " + rowCount + " Tweets. Do you want to print them?";
    n = JOptionPane.showOptionDialog(frame,
            question,
            "Question",
            JOptionPane.YES_NO_OPTION,
            JOptionPane.QUESTION_MESSAGE,       
            null,                               
            options,                            
            options[0]); 
    // do something with n here?
}

请注意，之前您在变量声明部分调用了 JOptionPane。当第一次创建对象时以及调用构造函数之前时，会调用此函数，这会让您感到困惑。我自己，我想知道所有这些是否可以包含在一个静态方法中。