Question

我想在我的GUI中插入文本字段中次要类的变量anzahl。计数在小班上工作，但我不知道我现在如何在GUI中获得计数值？在GUI中，我只想查看次要类的值。有人可以帮我解决代码示例吗？

小班：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JLabel;
import java.sql.DriverManager;

public class Count {

    static Connection conn;
    static Statement eintrag;
    static Statement eintrag2;
    static JLabel textPB1;
    static String ausgabe;
    public static String anzahl;
    Statement abfrage;
    int i;
    ResultSet res;
    private int num;

    Count() {

        try {

              Class.forName("org.mariadb.jdbc.Driver");

                    Connection con = java.sql.DriverManager.getConnection("jdbc:mariadb://fm-s012mp.fhws.de","Java","xyc");

                    Statement s = con.createStatement();

                    ResultSet res;

                    res = s.executeQuery("SELECT COUNT (*) AS anzahl FROM `lagersystem_test`.`00_hauptdatenbank` WHERE Boxinhalt > '0'" );

                    while (res.next() ) {

                          System.out.print(res.getString("anzahl") );


                          GUI_Lager.setTextExternally(res.getString("anzahl")); 
                                 }

                    res.close();
                    s.close();
                    con.close();

              }

              catch (Exception e) { System.out.println(""+e.getMessage());}
           }

        }

GUI :(简短形式）

public class GUI_Lager extends JFrame {

    private static final long serialVersionUID = 1L;

  JLabel textPB; // "Text Prozessbar
    static JLabel textPB1;
    (....)

  public GUI_Lager() {

  textPB1 = new JLabel(""); // Variable from the Class
        textPB1.setBounds(200, 10, 400, 25);
        textPB1.setVisible(true);
        add(textPB1);

  (....)

   }

    public static void setTextExternally(String text) {
            textPB1.setText(text);

            // TODO Auto-generated method stub

        }

}

}

Answer 1

要更新JLabel，您可以使用：

yourLabel.setText("your text");

因此，在您的问题中提供的代码的上下文中（假设它没有问题），您可以这样做：

while (res.next() == true) {

    //System.out.print(res.getString("anzahl") );
    //This "anzahl" i want to have in my GUI  

    textPB1.setText(res.getString("anzahl"));   //Now you should have the label set

}

如果由于某种原因JLabel不喜欢在循环中以这种方式改变，你也可以像这样实例化一个新的对象引用：

textPB1 = new JLabel(res.getString("anzahl"));

更新1：

如果你需要设置不同类的值，只需在类中使用textPB1创建一个方法，你将从你正在抓取数据库值的类中调用它，如下所示：

public static void setTextExternally(String text){
    textPB1.setText(text);
    //or
    textPB1 = new JLabel(text);
}

然后在你之前的循环中，执行以下操作：

while (res.next() == true) {

   //label should be set in other class using setter method below
    MainGUI.setTextExternally(res.getString("anzahl")); 

}

更新2：

此更新显示了Swing应用程序的一个特定示例，该应用程序与我已经提供的方法一起使用，现在我看到了基本的GUI代码。如果你需要一个直接的例子，我建议你从这些文件中建立起来：

您的GUI_Lager类：

import javax.swing.JFrame;
import javax.swing.JLabel;

public class GUI_Lager extends JFrame {

    private static final long serialVersionUID = 1L;
    JLabel textPB1;


    public GUI_Lager() {
        //no need for constructor, so it can be null
    }

    public void showGUI() {
        //let's make the GUI here
        this.setSize(300, 300);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setVisible(true);

        //-----------------your code
        //let's give it dummy text at first to ensure we can change it
        textPB1 = new JLabel("Dummy Text");
        textPB1.setBounds(200, 10, 400, 25);
        textPB1.setVisible(true);
        add(textPB1);
        //-----------------your code
    }

    public void setTextExternally(String text) {
        //alters the text of class variable/label textPB1
        textPB1.setText(text);
    }


}

然后是Count类：

import java.util.Scanner;
public class Count {

    public static void main(String[] args) {

        GUI_Lager gui = new GUI_Lager();
        gui.showGUI();      //you must show the GUI first

        //now we change the value, it will be done using your SQL selection from before
        gui.setTextExternally("Awesome, it works!");    

        //launch Count.java and the Swing application will have a
        // single label that says "Awesome, it works!"
        //...change your data as needed based on your specific implementation

        //but let's also show how to change it using console input
        Scanner scan = new Scanner(System.in);
        System.out.println("What do you want to change the text label to?");
        String text = scan.nextLine().trim();
        gui.setTextExternally(text);

    }
}

如何将SQL变量引入GUI？

1 个答案: