不顯示警告消息

Question

查看下面的代碼。

void viewStudent() throws ClassNotFoundException, SQLException { 
    try { 
     Class.forName("com.mysql.jdbc.Driver"); 
     connect2 = DriverManager 
       .getConnection("jdbc:mysql://localhost:3306/project?" 
         + "user=root&password=virus"); 

     statement2 = connect2.createStatement(); 

     preparedStatement2 = connect2 
       .prepareStatement("select regno from student where regno= " 
         + ""+Integer.parseInt(txt1.getText())+""); 
     resultSet2 = preparedStatement2.executeQuery(); 
     checkRegno(resultSet2); 

    } catch (ClassNotFoundException | SQLException e) { 
     throw e; 
    } finally { 
     close1(); 
    } 
} 

void checkRegno(ResultSet resultSet2) throws SQLException { 

    while (resultSet2.next()) { 

     int trno = Integer.parseInt(resultSet2.getString("regno")); 
     int regno = Integer.parseInt(txt1.getText()); 

     if (trno == regno) { 
      resultSet2 = statement2 
        .executeQuery("select * from student where regno= " + regno + ""); 
      writeResultSet(resultSet2); 
     } 
     else { 
      final Text warning = new Text("Register Number Not Found...!"); 
      warning.setFill(Color.RED); 
      warning.setStyle("-fx-font: 18 arial;"); 
      Stage dialogStage = new Stage(); 
      dialogStage.setTitle("Warning"); 
      dialogStage.initStyle(StageStyle.UTILITY); 
      dialogStage.setScene(new Scene(VBoxBuilder.create(). 
        children(warning).alignment(Pos.CENTER). 
        padding(new Insets(25, 25, 25, 25)).build())); 
      dialogStage.show(); 
     } 
    } 
} 

我在數據庫中有一個名爲'學生'的表。當「if（trno == regno）」爲真時，「writeResultSet（resultSet2）;」工作正常。當它爲假時，其他部分不起作用。我該如何解決這個問題？

Answer 1

很可能你沒有在FX線程上調用你的UI代碼。嘗試下一步：

Platform.runLater(new Runnable() { 

    @Override 
    public void run() { 
     final Text warning = new Text("Register Number Not Found...!"); 
     warning.setFill(Color.RED); 
     warning.setStyle("-fx-font: 18 arial;"); 
     Stage dialogStage = new Stage(); 
     dialogStage.setTitle("Warning"); 
     dialogStage.initStyle(StageStyle.UTILITY); 
     dialogStage.setScene(new Scene(VBoxBuilder.create(). 
       children(warning).alignment(Pos.CENTER). 
       padding(new Insets(25, 25, 25, 25)).build())); 
     dialogStage.show(); 
    } 
});