如何在NestedScrollView中使用RecyclerView创建ViewPager

Question

I am using NestedScrollView with ViewPager. NestedScrollView has a LinearLayout inside with some TextViews, TabLayout and ViewPager at the end. TextViews occupy most of the space and for ViewPager left a little space. ViewPager using two fragments, in one of them there is a few TextViews and ImageViews and in another fragment there is a RecyclerView.

When I set ViewPager's height to WRAP_CONTENT it takes only space that left and I can't scroll to see the rest of the first fragment, and the second fragment scoll inside little ViewPager.

When I set ViewPager's height to 1000dp for example, I am able to scroll down on first fragment, but the second fragment still scrolling inside little ViewPager. And after I scroll in fragment with RecyclerView scoll in the first Fragment not working anymore.

How can I fix scrolling problem and make ViewPager work with WRAP_CONTENT ?

Here is my code:

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

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary" />

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

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_scrollFlags="scroll"
        android:fillViewport="true">

        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/mainBackground"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="SOME TEXT" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="SOME TEXT" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="SOME TEXT" />

            <android.support.design.widget.TabLayout
                android:id="@+id/tabLayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

            <android.support.v4.view.ViewPager
                android:id="@+id/viewPager"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </LinearLayout>

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

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

Answer 1

I think you should override ViewPager like this:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    int height = 0;
    for (int i = 0; i < getChildCount(); i++) {
        View child = getChildAt(i);
        child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
        int h = child.getMeasuredHeight();
        if (h > height) height = h;
    }
    heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

Answer 2

maybe you can try :

 NestedScrollView scrollView = (NestedScrollView) findViewById (R.id.nest_scrollview);
    scrollView.setFillViewport (true);

such as: https://stackoverflow.com/a/33385207/4035627

Answer 3

@StevenZhang's solution almost worked for me but there was a problem when two tabs have different heights, the smaller tab takes the height of the bigger tab.

Based on this answer about how to make a dynamic height ViewPager I made a solution in Kotlin

Custom View Pager

class CustomViewPager: ViewPager {
    constructor(context: Context) : super(context)
    constructor(context : Context, attrs : AttributeSet) : super(context, attrs)

    private var currentView : View? = null

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {

        currentView?.let {
            it.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED))
            val h = it.measuredHeight
            val height = if (h > 0) h else 0
            val newHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY)
            super.onMeasure(widthMeasureSpec, newHeightMeasureSpec)
            return
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    }

    fun measureCurrentView(currentView: View?) {
        this.currentView = currentView
        requestLayout()
    }
}

In your custom PagerAdapter override setPrimaryItem

private var currentPosition = -1

override fun setPrimaryItem(container: ViewGroup, position: Int, `object`: Any) {
    super.setPrimaryItem(container, position, `object`)
    if (position != currentPosition) {
      val fragment = `object` as Fragment
      val pager = container as CustomViewPager
      if (fragment.view != null) {
         currentPosition = position
         pager.measureCurrentView(fragment.view)
      }
   }
}

You may also need to set isNestedScrollingEnabled of your RecyclerView to false

recyclerView.isNestedScrollingEnabled = false