java setText is not working in JLabel

Question

Trying to display sql results in a JLabel. I'm using netbeans so it does auto code generation for the swing components.

Welcome_screen.java, main method

package my.welcomescreen;
import java.io.InputStream;
import java.sql.*;
import javax.swing.*;

public class Welcome_screen extends javax.swing.JFrame {

  public Welcome_screen() {
    initComponents();

  }

  private void initComponents() {

    jLabel9 = new javax.swing.JLabel();

  }

  public static void main(String args[]) {
    Welcome_screen courses = new Welcome_screen();
    courses.getCourses();


    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Welcome_screen().setVisible(true);

         }
      });
   }

  public void getCourses(){

    db obj = new db();
    obj.dbconnect();
    String Query = "select * from courses";
    try{
        Connection con = obj.dbconnect();
        Statement st = con.createStatement();
        ResultSet rs = st.executeQuery(Query);

        if(rs.next()){
            //System.out.println(rs.getString("name"));
            jLabel9.setText(rs.getString("name"));
        }



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


}

private javax.swing.JLabel jLabel9;

}

db.java, database connect file.

package my.welcomescreen;
import java.sql.*;

public class db {

    public static Connection dbconnect(){
        Connection con=null;
         try {

          Class.forName("com.mysql.jdbc.Driver");
          con = DriverManager.getConnection("jdbc:mysql://localhost/st2", "root", "");


    }
      catch (ClassNotFoundException | SQLException e){
      System.out.println(e);
  }
     return con; 
 }

}

when i print sql results to the command line it works. expected result is displaying. But in the JLabel nothing happens. Not even an error is occurring. I can't find what's wrong. A little help would be appreciated !

Answer 1

Please try this like -

jlabel.setText("Your Text");
jLabel.setVisisble(true);

Answer 2

At first: YOU HAVE TO PLACE THE JLABEL on the Frame:

getContentpane().add(label9);

And after on i recommend to take a look at the following Methods:

rame.setSize(width, height);
Frame.getContentPane();
Container/JComponent.add(Component c);
Component.setLayout(LayountManager manager);

I recommend to watch more vids or read Blogs about Swing bevore continuing. But here is the code u should use:

private void initComponents() {

    label9 = new JLabel();
    label9.setText("SOME TEXT");
    JPanel p = new JPanel();
    p.setSize(100, 50);
    p.setLayout(new FlowLayout());
    p.add(jLabel9);
    p.setVisible(true);

    setSize(200, 200);
    getContentPane().add(p);

}

Try to call

jlabel9.setText("Your readen text!");
jlabel9.repaint();

It will repaint the label and update the content.

Answer 3

You need to locate jLabel9 on the jPanel and it on Frame. One of the way is to use a constructor. As your class is exended from JFrame, you don't need to use this.add() or JFrame jf = new JFrame();

private void initComponents() {

    jLabel9 = new javax.swing.JLabel();
    jLabel9.setBackground(Color.red);
    jLabel9.setVisible(true);
    jLabel9.setText("Hello");
    JPanel jp = new JPanel();
    jp.setSize(100, 50);
    jp.add(jLabel9);
    jp.setVisible(true);

    setSize(200, 200);
    add(jp);
    setVisible(true);

}

or directly on JFrame

private void initComponents() {

    jLabel9 = new javax.swing.JLabel();
    jLabel9.setBackground(Color.red);
    jLabel9.setVisible(true);
    jLabel9.setText("Hello");
        setSize(200, 200);
        add(jLabel9);
// one of other way to use contentpane
// getContantPane().add(jLabel9);
        setVisible(true);
    }