How to set margin to main ConstraintView in android?

Question

I want to set margin to my main layout with programmatically. I use layout params as following code.

val parMain = mainLayout?.layoutParams as ConstraintLayout.LayoutParams

But i have some error like

android.view.ViewGroup$LayoutParams cannot be cast to androidx.constraintlayout.widget.ConstraintLayout$LayoutParams

if I change the code as Android wants like this:

val parMain = mainLayout?.layoutParams as ViewGroup.LayoutParams

There is no set margin function in my layoutParams.

Thats my xml code.

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/detail_feed_scrool_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/transparent"
    tools:context=".DetailActivity">

    <View
        android:id="@+id/shadow_view"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:background="#99000000"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/detail_feed_view_pager_activity"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">
    </androidx.viewpager.widget.ViewPager>

    <FrameLayout
        android:id="@+id/detail_fragment_frame_layout"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/white"
        android:visibility="gone"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">
    </FrameLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

How can i set margin in my case?

Yes it is. var mainLayout = findViewById(R.id.detail_feed_scrool_view) — Murat Çakır, Feb 10 '20 at 10:30
i think you are interested in why is that, don't you? so i'm providing the detailed answer — Ashwini Saini, Feb 10 '20 at 10:45
I tried to use FrameLayout.LayoutParams. Just error messages change like this: android.view.ViewGroup$LayoutParams cannot be cast to android.widget.FrameLayout$LayoutParams — Murat Çakır, Feb 10 '20 at 10:51
First of all, thanks for interested my question. I actually used Frame.LayoutParams on different constraintLayout in this project. But i do not know why i can not use in this view. — Murat Çakır, Feb 10 '20 at 11:20
i explained the `LayoutParams` concept in answer, please check the answer now, you will be able to solve your problem afterword — Ashwini Saini, Feb 10 '20 at 11:22

Ashwini Saini · Accepted Answer · 2020-02-10T11:29:37.940

A Layout/View's LayoutParams depends on it's parent layout

For example:-

If you will try to get layout param from your <View> who have id android:id="@+id/shadow_view" then the layoutParams will be ConstraintLayout.LayoutParams type.

Why? because ConstraintLayout is the parent layout of <View> . now same goes for the <ViewPager>, it's direct parent is also ConstraintLayout, so same ConstraintLayout.LayoutParams

and also when you want to set layoutParams on any View/Layout, Always look for the direct parent layout and set same as that parent layout type layoutParams

Now Answer to Your Problem

In your case, you don't have any parent layout that's why you are getting the ViewGroup.LayoutParams.

ViewGroup is parent class of layouts, more like a generic class and this class don't have margins.

easiest solution for you will be just wrap your whole layout in another layout that you want, so there will be a parent for your ConstraintLayout and your LayoutParams will be the type of layout that you used to wrap

something like this

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.constraintlayout.widget.ConstraintLayout xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/detail_feed_scrool_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorPrimary">

        <View
            android:id="@+id/shadow_view"
            android:layout_width="wrap_content"
            android:layout_height="0dp"
            android:background="#99000000"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/detail_feed_view_pager_activity"
            android:layout_width="0dp"
            android:layout_height="0dp"
            app:layout_behavior="@string/appbar_scrolling_view_behavior"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

        </androidx.viewpager.widget.ViewPager>

        <FrameLayout
            android:id="@+id/detail_fragment_frame_layout"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:background="@android:color/white"
            android:visibility="gone"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

        </FrameLayout>

    </androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>

Now when you will try to get the LayoutParams you will get them as LinearLayout type

Okay i will try this answer. Thank you. I will feedback to here when i will try to your advice. Your answer look like so make sense for me. — Murat Çakır, Feb 10 '20 at 11:44

How to set margin to main ConstraintView in android?

1 Answers1