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javaandroidandroid-viewpagerandroid-tablayout

How to make toolbar visible again which is previous hidden using layout_scrollFlags, when swipe to different viewpager page

Currently, I have the following page with ViewPager

enter image description here

When the page in INFO tab is scrolled, toolbar will be hidden. This behavior is implemented via CoordinatorLayout, AppBarLayout and app:layout_scrollFlags

<?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:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:elevation="0dp"
        android:elevation="0dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" >

        <android.support.v7.widget.Toolbar
            app:layout_scrollFlags="scroll|enterAlways|snap"

            android:id="@+id/toolbar"
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            android:minHeight="?attr/actionBarSize"
            android:background="@android:color/transparent"
            app:elevation="0dp"
            android:elevation="0dp"
            app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabIndicatorColor="?attr/detailedStockTabIndicatorColor" />
    </android.support.design.widget.AppBarLayout>

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

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

So, this is how it looks like after scrolling.

After Scroll, Toolbar is hidden

enter image description here

Since this is a ViewPager, if I swipe to FINANCIAL tab, it will look like the following.

Followed by Swipe

enter image description here

Since, the page in FINANCIAL tab is not scroll-able, we hope not to hide the Toolbar.

I was wondering, how to make toolbar visible again which is previous hidden using layout_scrollFlags, when swipe to different ViewPager page?

Solution

  • you can do it like this :

    final AppBarLayout appBarLayout = view.findViewById(R.id.app_bar_layout);
    viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            if (position == 1)
                appBarLayout.setExpanded(true, true);
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

    so when viewPager is in unscrollable page it expands and toolbar appears