Fixed view in ViewPager's content layout, under CoordinatorLayout

Question

My app has an Activity with TabLayout, and 3 Fragments. In Activity's layout, I have CoordinatorLayout with ViewPager. I need to animate toolbar as well. Now In Fragments layout, I need to put a fixed TextView at the bottom. Given below is the XML of activity and fragment.

I am facing the problem that this fixed TextView in Fragment's layout is going under the bottom navigation bar and is scrolling also, that I don't want.

How can achieve this ?

activity.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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/clMain"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/app_name"
                android:textColor="#FFFFFF"
                android:textSize="22sp"
                android:textStyle="bold" />
        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</android.support.design.widget.CoordinatorLayout>

fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorWhite"
    android:orientation="vertical">

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/rlParent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="fill_vertical"
        android:layout_weight="1"
        android:fitsSystemWindows="true"
        android:orientation="vertical">


    </android.support.v4.widget.NestedScrollView>

    <TextView
        android:id="@+id/tvConfirmOrder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorDarkGreen"
        android:gravity="center"
        android:padding="10dp"
        android:text="@string/confirm_order"
        android:textColor="@color/colorWhite"
        android:textSize="18sp"
        android:textStyle="bold"></TextView>
</LinearLayout> 

Answer 1

As you want this bottom fixed TextView for each fragment, it can be solved by transferring your TextView to activity.xml and adding a custom behavior to it.

So, firstly, create a class that represents custom behavior:

public class FixedBottomViewBehavior extends CoordinatorLayout.Behavior<View> {

    public FixedBottomViewBehavior() {
    }

    public FixedBottomViewBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, View child, View dependency) {
        //making our bottom view depends on ViewPager (or whatever that have appbar_scrolling_view_behavior behavior)
        return dependency instanceof ViewPager;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
        if (ViewCompat.isLaidOut(parent)) {
            //attach our bottom view to the bottom of CoordinatorLayout
            child.setY(parent.getBottom() - child.getHeight());

            //set bottom padding to the dependency view to prevent bottom view from covering it
            dependency.setPadding(dependency.getPaddingLeft(), dependency.getPaddingTop(),
                    dependency.getPaddingRight(), child.getHeight());
        }
        return false;
    }
} 

There is no magic here, we're just making our bottom view dependent on some view with appbar_scrolling_view_behavior (in our case it's ViewPager) and then attaching it to the bottom of CoordinatorLayout and setting some padding to dependency.

Secondly, change your activity.xml, by adding your TextView there:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/clMain"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/app_name"
                android:textColor="#FFFFFF"
                android:textSize="22sp"
                android:textStyle="bold" />
        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <TextView
        android:id="@+id/tvConfirmOrder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/colorDarkGreen"
        android:gravity="center"
        android:padding="10dp"
        android:text="@string/confirm_order"
        android:textColor="@color/colorWhite"
        android:textSize="18sp"
        android:textStyle="bold"
        app:layout_behavior="your.package.name.FixedBottomViewBehavior" />

</android.support.design.widget.CoordinatorLayout>

Make sure you've removed your TextView from fragment.xml. Don't forget also to change your.package.name.FixedBottomViewBehavior to your package name exactly.

Voila! That should work like a charm with proper toolbar animation and fixed view at the bottom.

In addition: if you don't know how to pass your OnClick event to your fragments you can follow this way in your Activity:

    public interface OnConfirmOrderClickListener {
        void onConfirmOrderClick(View v);
    }

    public Fragment getActiveFragment() {
        String name = makeFragmentName(pager.getId(), pager.getCurrentItem());
        return getSupportFragmentManager().findFragmentByTag(name);
    }

    public String makeFragmentName(int viewId, int index) {
        return "android:switcher:" + viewId + ":" + index;
    } 

    tvConfirmOrder.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Fragment current = getActiveFragment();
            if (current instanceof OnConfirmOrderClickListener)
                ((OnConfirmOrderClickListener) current).onConfirmOrderClick(v);
        }
    });

Don't forget to make your fragments implements OnConfirmOrderClickListener. Hope that helps!