notes

  //Custom variables declaration
    private ArrayList students = new ArrayList();
    private String[] courses ={"Maths", "English", "Physics", "PE", "Sociology"};
    private String[] columnNames={"Име", "Фамилия","Среден Успех","Редовен/задочен"};


//custom methods
    private void addStudent(){
        String name = f1.getText();
        String fam = f2.getText();
        if(name==null||name==""||fam==""||fam==null||
                (!radio1.isSelected() && !radio2.isSelected())){
            JOptionPane.showMessageDialog(rootPane, "Моля попълнете цялата информация",
                    "Грешка", JOptionPane.ERROR_MESSAGE);
            return;
        }
        String disc1 = (String)combo1.getSelectedItem();
        String disc2 = (String)combo2.getSelectedItem();
        String disc3 = (String)combo3.getSelectedItem();
        int mark1 = Integer.parseInt(spin1.getValue().toString());
        System.out.println("mark1: "+mark1);
        int mark2 = Integer.parseInt(spin2.getValue().toString());
        System.out.println("mark1: "+mark2);
        int mark3 = Integer.parseInt(spin3.getValue().toString());
        System.out.println("mark1: "+mark3);
        String type = radio1.isSelected() ? "Редовно" : "Задочно";
        double av = (mark1 + mark2 + mark3) / 3;
        ArrayList student = new ArrayList();
        student.add(name);
        student.add(fam);
        student.add(av);
        student.add(type);
        students.add(student);
        f1.setText("");
        f2.setText("");
        combo1.setSelectedIndex(0);
        combo2.setSelectedIndex(0);
        combo3.setSelectedIndex(0);
        spin1.setValue(2);
        spin2.setValue(2);
        spin3.setValue(2);
        myModel.addRow(new Object[]{"","","",""});
        myModel.setValueAt(name, myModel.getRowCount()-1, 0);
        myModel.setValueAt(fam, myModel.getRowCount()-1, 1);
        myModel.setValueAt(av, myModel.getRowCount()-1, 2);
        myModel.setValueAt(type, myModel.getRowCount()-1, 3);
    }

    private void calculate(){
        double srUspeh=0;
        int redCount=0;
        int zadCount=0;
        if(myModel.getRowCount()==0) return;
        for(int i=0;i<myModel.getRowCount()-1;i++){
            srUspeh += (Double)myModel.getValueAt(i, 2);
            if(myModel.getValueAt(i, 3).equals("Редовно")){
                redCount++;
            }
            else zadCount++;
        }
        srUspeh /= myModel.getRowCount();
        usField.setText(String.valueOf(srUspeh));
        redField.setText(String.valueOf(redCount));
        zadField.setText(String.valueOf(zadCount));
    }

    private DefaultTableModel myModel = new DefaultTableModel(columnNames, 0){

        @Override
        public boolean isCellEditable(int row, int column) {
            return false; //To change body of generated methods, choose Tools | Templates.
        }
    };