Comment empiler des champs de texte verticalement sur un Panel?

Question

Je travaille sur le petit programme de calcul GPA GUI. J'ai mis en place mon bouton pour que, une fois cliqué, des champs de texte et des comboboxes soient ajoutés à un panneau, mais chaque fois que l'on clique dessus, tous les add-ons sont simplement horizontaux sur une ligne. Y a-t-il un moyen de manipuler la mise en page afin que les nouveaux ajouts commencent une nouvelle ligne en dessous des existants? THX!

Voici mon code:

public class gpaCalculator extends JFrame { 
    ArrayList<Class> allClasses = new ArrayList<Class>(); 
    ArrayList<Class> classesTaken = new ArrayList<Class>(); 
    ArrayList<Class> classesTaking = new ArrayList<Class>(); 
    ArrayList<Class> classesWillTake = new ArrayList<Class>(); 

    private JFrame frame; 
    private JPanel panel1; 
    private JPanel panel2; 
    private JPanel panel3; 

    private JButton addNewCourse; 
    private JButton finishedCalculate; 
    private JButton showClassesEntered; 
    private JButton removeAllClass; 

    /** 
    * Courses 
    **/ 
    public gpaCalculator() { 
     frame = new JFrame("GPA Calculator"); 
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     int height = (int) Toolkit.getDefaultToolkit().getScreenSize().getHeight(); 
     int width = (int) Toolkit.getDefaultToolkit().getScreenSize().getWidth(); 
     this.setSize(width, height); 
     this.setLayout(new FlowLayout(8)); 
     panel1 = new JPanel(new FlowLayout(FlowLayout.LEFT)); 
     panel2 = new JPanel(new FlowLayout(FlowLayout.CENTER)); 
     panel3 = new JPanel(new FlowLayout(FlowLayout.RIGHT)); 

     addNewCourse = new JButton("Add a new course!"); 
     addNewCourse.addActionListener(new ButtonListener()); 

     finishedCalculate = new JButton("Calculate my GPA & Enter target GPA"); 
     finishedCalculate.addActionListener(new ButtonListener2()); 

     showClassesEntered = new JButton("Display classes entered"); 
     showClassesEntered.addActionListener(new ButtonListener3()); 

     removeAllClass = new JButton("Remove all entered classes"); 
     removeAllClass.addActionListener(new ButtonListener4()); 

     this.add(addNewCourse); 
     this.add(finishedCalculate); 
     this.add(showClassesEntered); 
     this.add(removeAllClass); 

     this.add(panel1); 
     this.add(panel2); 
     this.add(panel3); 

     this.setLocationRelativeTo(null); 
     this.setVisible(true); 
    } 

    private class ButtonListener implements ActionListener { 

     @Override 
     public void actionPerformed(ActionEvent args) { 

      String[] courseCreditHourCombo = {"1", "2", "3", "4"}; 
      String[] courseGradeCombo = {"A+", "A", "A-", "B+", "B", "B-", "C+", "C", "C-", "D", "E", "F", "U"}; 
      String[] courseTypeCombo = {"Have taken", "Currently taking", "Will be taking"}; 
      JLabel creditHourLabel = new JLabel("Course credit houe"); 
      JLabel nameLabel = new JLabel("Course name: "); 
      JLabel calculatedGPALabel = new JLabel("Calculated GPA"); 
      JLabel courseTypeLabel = new JLabel("Course status"); 
      JLabel gradeLabel = new JLabel("Course grade "); 
      JComboBox courseCreditHour = new JComboBox(courseCreditHourCombo); 
      JTextField courseName = new JTextField(10); 
      courseName.setEditable(true); 
      JComboBox courseGrade = new JComboBox(courseGradeCombo); 
      JComboBox courseType = new JComboBox(courseTypeCombo); 
      JTextField calculatedGPA = new JTextField(10); 

      panel1.add(nameLabel); 
      panel1.add(courseName); 
      panel1.add(creditHourLabel); 
      panel1.add(courseCreditHour); 
      panel1.add(courseTypeLabel); 
      panel1.add(courseType); 
      panel1.add(gradeLabel); 
      panel1.add(courseGrade); 

      int classCredit = (Integer) courseCreditHour.getEditor().getItem(); 
      String className = courseName.getText(); 
      String classGrade = (String) courseGrade.getEditor().getItem(); 
      String classType = (String) courseType.getEditor().getItem(); 

      Class theClass = new Class(className, classGrade, classType, classCredit); 
      allClasses.add(theClass); 

      if (classType.equals("Have taken")) { 
       Class newClass = new Class(className, classGrade, classType, classCredit); 
       classesTaken.add(newClass); 
      } else if (classType.equals("Currently taking")) { 
       Class newClass = new Class(className, classType, classCredit); 
       classesTaking.add(newClass); 
      } else { 
       Class newClass = new Class(className, classType, classCredit); 
       classesWillTake.add(newClass); 
      } 
     } 
    } 

    private class ButtonListener2 implements ActionListener { 

     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      // TODO Auto-generated method stub 
      panel2.removeAll(); 
      JLabel currentGPALabel = new JLabel("Current GPA: "); 
      JLabel currentGPA = new JLabel(); 
      JLabel targetGPALabel = new JLabel("Target GPA: "); 
      JTextField targetGPA = new JTextField(10); 
      targetGPA.setEditable(true); 

      panel2.setSize(200, 200); 
      panel2.add(currentGPALabel); 
      panel2.add(currentGPA); 
      panel2.add(targetGPALabel); 
      panel2.add(targetGPA); 

      double counter = 0; 
      for (Class c : classesTaken) { 
       counter = counter + c.getWeightedClassGPA(); 
      } 
      double currentGPADouble = counter/(classesTaken.size() + 1); 
      currentGPA.setText(String.valueOf(currentGPADouble)); 
      //System.out.println(currentGPADouble); 
     } 
    } 

    private class ButtonListener3 implements ActionListener { 
     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      // TODO Auto-generated method stub 
      panel3.removeAll(); 
      JLabel classesEntered = new JLabel("Courses entered: "); 

      panel3.setSize(200, 200); 
      panel3.add(classesEntered); 

      classesEntered.setText("Classes entered: " + allClasses); 
     } 
    } 

    private class ButtonListener4 implements ActionListener { 
     @Override 
     public void actionPerformed(ActionEvent e) { 
      // TODO Auto-generated method stub 
      allClasses.clear(); 
     } 
    } 
} 

Answer 1

Placez-les dans un GridBagLayout.

http://docs.oracle.com/javase/6/docs/api/java/awt/GridBagLayout.html