how to create a JTable with POJOs with a single table model

Question

I’m trying to create a GUI to display the content of a database. I’m using a JTable for that. I want a constructor that takes a list of POJOs and eventually column titles. I want also my JTable to be able to return the selected POJO (for example when I doubleclick on a row). Do I really need to create a table model for each POJO or is there a better way?

I’ve made some searchs on similar topics, but I didn’t find any answer that uses a single table model for all POJOs and none of them has a method that returns a POJO.

Here is the description of my database tables and POJOs:

Database tables:

• students (id, firstname, lastname, birthdate, grade_id, phonenumber)
• grades (id, grade)
• authors (id, firstname, lastname, nationality_id)
• nationalities (id, nationality)
• books (id, title, author_id, student_id)

POJOs:

• Grade (int id, String grade)
• Student (int id, String firstname, String lastname, Grade grade)
• Author (int id, String firstname, String lastname, Nationality nationality)
• Nationality (int id, String nationality)
• Book (int id, String title, Author author, Student student)

Answer 1

Here is as example of solution using reflection and annotations.

public class Worker {

    @Updatable(false)
    @Order(1)
    @ColumnName("ID")
    private int id; 

    @Updatable(true)
    @Order(2)
    @ColumnName("FIRST NAME")
    private String firstName; 

    @Updatable(true)
    @Order(3)
    @ColumnName("LAST NAME")
    private String lastName; 

    public Worker() {
    }

    public Worker(int id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Order(1)
    public int getId() {
        return id;
    }

    @Order(1)
    public void setId(int id) {
        this.id = id;
    }

    @Order(2)
    public String getFirstName() {
        return firstName;
    }

    @Order(2)
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @Order(3)
    public String getLastName() {
        return lastName;
    }

    @Order(3)
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

-

@Retention(RetentionPolicy.RUNTIME)
public @interface Order {
    int value(); 
}

-

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface ColumnName {
    String value(); 
}

-

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Updatable {
    boolean value(); 
}

-

public class ComparatorReflection<T extends AccessibleObject & Member> implements Comparator<T>{

    @Override
    public int compare(T o1, T o2) {
        Order or1 = o1.getAnnotation(Order.class); 
        Order or2 = o2.getAnnotation(Order.class); 
        if (or1 != null && or2 != null && or1.value() - or2.value() != 0) {
            return or1.value() - or2.value(); 
        }
        return o1.getName().compareTo(o2.getName()); 
    }

}

-

public class ModelDAO extends AbstractTableModel {

    private List<?> data; 

    public ModelDAO(List data) {
        this.data = data;
    }

    @Override
    public int getRowCount() {
        return this.data.size(); 
    }

    @Override
    public int getColumnCount() {
        return data.get(0).getClass().getDeclaredFields().length; 
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        try {
            Method[] methods = data.get(rowIndex).getClass().getDeclaredMethods(); 
            Arrays.sort(methods, new ComparatorReflection<Method>()); 
            return methods[2*columnIndex].invoke(data.get(rowIndex), null);
        } catch (Exception ex) {
            ex.printStackTrace(); 
        }
        throw new UnsupportedOperationException("Not supported yet."); 
    }

    @Override
    public Class<?> getColumnClass(int columnIndex) {
        Field[] fields = data.get(0).getClass().getDeclaredFields(); 
        Arrays.sort(fields, new ComparatorReflection<Field>()); 
        return fields[columnIndex].getType(); 
    }

    @Override
    public String getColumnName(int column) {
        Field[] fields = data.get(0).getClass().getDeclaredFields(); 
        Arrays.sort(fields, new ComparatorReflection<Field>()); 
        return fields[column].getAnnotation(ColumnName.class).value(); 
    }

    @Override
    public boolean isCellEditable(int rowIndex, int columnIndex) {
        Field[] fields = data.get(rowIndex).getClass().getDeclaredFields(); 
        Arrays.sort(fields, new ComparatorReflection<Field>()); 
        return fields[columnIndex].getAnnotation(Updatable.class).value(); 
    }
}