CODEWITHSUNDEEP
javaandroidandroid-view
Murdok
Murdok

Reputation: 126

Is List<View> worth it?

Problem

I Have a custom activity that load graphics from an XML file, where i have a lot of Buttons, Images and Text.

My Implementation Planning

For implementation i want to use android classes like ImageButton, TextView and ImageView.

I have thinking to use a List<View> for looping all View objects and inflating into a RelativeLayout.

My doubt

Is better a List<View> or List<ImageButton>, List<TextView> and List<ImageView>?

Method implementation in ImageButton or ImageView (Like onClick or some other event), is lost when i convert it to a View object?

Example of code i planned:

ImageButton imageButton = new ImageButton(getContext());

//Implementation of methods and events...
List<View> list = new ArrayList<View>;
list.add(imageButton);

Upvotes: 0

Views: 99

Answers (2)

Doc
Doc

Reputation: 11651

You biggest doubt here is

Method implementation in ImageButton or ImageView (Like onClick or some other event), is lost when I convert it to a View object?

NO, this does not happen.

Consider two classes

class Parent{
    void big(){}
}

and

class Child extends Parent{
    void small(){}
}

If you say

Child c = new Child();

then you can use

c.big(); as well as c.small();

but if you say

Parent c = new Child();

you are allowed to use

c.big();

But for calling small() inside Child class you need to cast it

Child ch = (Child)c;
ch.small();

Now if there a number of subclasses, each with different methods available to them which like Child1 with small1() and Child2 with small2() and so on then you can use instanceof for casting

like

if(ch1 instanceof Child1)
{   
    Child1 c1 = (Child1)ch1;
    c1.small1();
}
if(ch2 instanceof Child2)
{
    Child2 c2 = (Child2)ch2;
    c2.small2();
}

Upvotes: 1

ronginat
ronginat

Reputation: 2005

The list only holds references of your components. If you create an ImageButton for exmaple, set a click listener and add it to the List<View>, nothing will get lost. Only thing is you won't know each view's actual type.

To get the true class of a generic View you can use multiple if statements that check all of your component types, like:

if (view instanceof ImageButton) {
    ImageButton imageButton = (ImageButton)view;
}

instanceof checks if an object is of a specific class or extends it. So make sure you first check for ImageButton before ImageView for example, because its a descendant of the class.

Upvotes: 1

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