Access Class Variable on general Object of that class

Question

I have a lots of classes for example this one:

public class DepartmentST {
    public Long id = null;
    public String name = null;
    public String comments = null;
    public Long[] profiles = null;
    public Boolean default_val = false;
}

In main class I create objects of those classes and sent it to general method for example:

DepartmentST mydepartment = new DepartmentST();
generalMethod(mydepartment);

In general Method I want to access to object fields (this my question how?)

public generalMethod(Object myObj) {
    Field[] fields = myObj.getClass().getFields();
    for(Field field : fields) {
        String fieldName = field.getName();
        // I want to access that field how can i tell myObj.fielName ?
    }
}

I'm new in Java I don't know it's stupid question or not.

thanks for any help in advance.

Answer 1

see http://docs.oracle.com/javase/7/docs/api/java/lang/reflect/Field.html#get(java.lang.Object)

public generalMethod(Object myObj) {
    Field[] fields = myObj.getClass().getFields();
    for(Field field : fields) {
        String fieldName = field.getName();
        // I want to access that field how can i tell myObj.fielName ?

        Class c = field.getType();
        if (c instanceOf Integer) {
            Integer value = field.getInt (myObj);
        }

        // or

        Object value = field.get (myObj); 

    }
}

Answer 2

You need to "cast" the object to a DepartmentST object:

if (myObj instanceof DepartmentST) {
    DepartmentST department = (DepartmentST) myObj;
    // continue with code

Then use that object instead of myObj.

Answer 3

Basically this code breaks the encapsulation. You need private fields, and you access them through getters and setters. Reflection is another way to go (depending on the context).