background color is not setting properly. it display different color than set color

Question

I am trying to set theme run time. and facing one problem that i have one layout which i use further to change its color depend on theme. But it display the random color rather than color which i set.

Here is code which i had tried.

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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activity.DashboardActivity">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@android:color/transparent"
            android:orientation="vertical">

            <LinearLayout
                android:id="@+id/gradient_layout"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="0.4"
                android:orientation="vertical">

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="10dp"
                    android:layout_marginTop="20dp"
                    android:layout_marginEnd="10dp"
                    android:gravity="center"
                    android:text="@string/app_name"
                    android:textColor="@android:color/background_light"
                    android:textSize="20sp"
                    android:textStyle="bold" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="@string/company_name"
                    android:textColor="@android:color/background_light"
                    android:textSize="24sp" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1.6"
                android:background="@color/white_gray" />
        </LinearLayout>
    </FrameLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Java Code in onCreate() is as :

preferences = getSharedPreferences("ThemePreference", MODE_PRIVATE);
        themeColor = preferences.getInt("primaryColor", R.color.colorPrimary);
        themeColorDark = preferences.getInt("darkColor", R.color.colorPrimary);

        if (themeColor == R.color.orange_colorPrimary) {
            setTheme(R.style.AppTheme_orange);
        } else if (themeColor == R.color.red_colorPrimary) {
            setTheme(R.style.AppTheme_red);
        } else if (themeColor == R.color.green_colorPrimary) {
            setTheme(R.style.AppTheme_green);
        } else if (themeColor == R.color.colorPrimary) {
            setTheme(R.style.AppTheme);
        }

gradientLayout = findViewById(R.id.gradient_layout);
gradientLayout.setBackgroundColor(themeColor);

I want to set color in gradientLayout which color i will get in my preference primaryColor.

if anyone is having solution than please reply.

Thank You in advance !!