Get field name and check array list is there?

Question

With below method I can pass any class and I can get values of the list.

public static void GetFieldName(ArrayList<Object> object)
            throws IllegalArgumentException, IllegalAccessException {

    for (Object obj : object)
        for (Field field : obj.getClass().getDeclaredFields()) {
            Log.i("Field", field.getName() + ":" + field.get(obj));

        }
    }

Suppose I have two classes Student and Employee. I don't know how many fields are there in both of them. Still I can get value of every field using the above method.

Now, I want to check if a particular class has any ArrayList within, i.e Suppose the Student class has an Arraylist<Address> of Address class. So can I get the array list values?

score 1 · Answer 1 · edited May 23 '17 at 12:28

1

You need to use the Class#isAssignableFrom(Class cls) method.

for (Field field : obj.getClass().getDeclaredFields()) {
    Log.i("Field", field.getName() + ":" + field.get(obj));
    if (field.getType().isAssignableFrom(ArrayList.class) {
        field.setAccessible(true); //needed for private fields 
        Object value = field.get(c); //getting the private field value
        ArrayList<Address> x = (ArrayList<Address>) value; // cast to ArrayList<Address>
    }
}

More info:

Difference between instanceof and isAssignableFrom()

edited May 23 '17 at 12:28

Community

1
1

answered Sep 21 '13 at 07:38

Konstantin Yovkov

62,134
8
100
147

How can I get value from arraylist if condition is true? – nil Sep 21 '13 at 08:11
Checkout the [Field](http://docs.oracle.com/javase/6/docs/api/java/lang/reflect/Field.html) javadoc. – Konstantin Yovkov Sep 21 '13 at 08:17
Try `Object value = field.get(obj)`. – Konstantin Yovkov Sep 21 '13 at 08:38
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/37775/discussion-between-nil-and-kocko) – nil Sep 21 '13 at 09:32
I have asked this question "So can I get that array list values?", You have given half answer. that's why I have unaccepted your answer. – nil Sep 21 '13 at 09:34

score 0 · Answer 2 · answered Sep 21 '13 at 07:40

0

You can call getDeclaringClass() on field object and compare it to desired class (e.g. ArrayList)

answered Sep 21 '13 at 07:40

tomieq

29
1
4

Get field name and check array list is there?

2 Answers2