How can I make my layout scroll both horizontally and vertically?

Since other solutions are old and either poorly-working or not working at all, I've modified NestedScrollView, which is stable, modern and it has all you expect from a scroll view. Except for horizontal scrolling.

Here's the repo: https://github.com/ultimate-deej/TwoWayNestedScrollView

I've made no changes, no "improvements" to the original NestedScrollView except for what was absolutely necessary. The code is based on androidx.core:core:1.3.0, which is the latest stable version at the time of writing.

All of the following works:

• Lift on scroll (since it's basically a NestedScrollView)
• Edge effects in both dimensions
• Fill viewport in both dimensions

The problem with most of the answers here is that they only achieve vertical or horizontal scroll, BUT not diagonal (horizontal AND vertical at the same time).

The easiest way I've found to get it working is:

• Create two new classes extending HorizontalScrollView and ScrollView (use whatever name, like "ScrollViewX" and "ScrollViewY").
• Make a new XML and use the class extending HorizontalScrollView inside the one extending ScrollView.
• Inside the two classes, override their onTouch methods to always return false (override and use performClick() too, for accessibility reasons).
• Use a GestureDetector and update the scrolling of both classes with it.

Creating the classes isn't really required, since you could just set an onTouch listener for both. But I believe it's better in terms of organization and it may be useful if you require more customizations later.

The only problem I've found is that, since one ScrollView is inside the other, now one of the scrollbars is only going to be visible when you scroll while being on the edge of the view.

A workaround could be: either don't use scrollbars, or make a custom view to replace said scrollbar (you set its size according to the ScrollView size and move it as the scroll is updated).

Note: I tried to describe it as much as I could. If someone needs more details, let me know

You can do this by using below code

<HorizontalScrollView
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">
                    <ScrollView
                        android:layout_width="wrap_content"
                        android:layout_height="match_parent">
                        <LinearLayout
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content">
                            
                        </LinearLayout>
                    </ScrollView>
    </HorizontalScrollView>

This implementation can always display both horizontal and vertical scrollbars

activity_main.xml

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

    <!-- vertical scroll view -->
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        android:fadeScrollbars="false"
        android:scrollbarSize="@dimen/scroll_bar_size">

        <!-- horizontal scroll view hidden scroll bar -->
        <HorizontalScrollView
            android:id="@+id/real_horizontal_scroll_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fillViewport="true"
            android:scrollbars="none">

            <!-- content view -->
            <EditText
                android:id="@+id/real_inside_view"
                android:layout_width="wrap_content"
                android:layout_height="match_parent" />
        </HorizontalScrollView>
    </ScrollView>

    <!-- fake horizontal scroll bar -->
    <HorizontalScrollView
        android:id="@+id/fake_horizontal_scroll_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:fadeScrollbars="false"
        android:scrollbarSize="@dimen/scroll_bar_size">

        <!-- fake content view that has width equals the real content view -->
        <View
            android:id="@+id/fake_inside_view"
            android:layout_width="wrap_content"
            android:layout_height="@dimen/scroll_bar_size" />
    </HorizontalScrollView>
</RelativeLayout>

MainActivity.java

    final EditText realInsideView = findViewById(R.id.real_inside_view);
    final HorizontalScrollView realHorizontalSv = findViewById(R.id.real_horizontal_scroll_view);

    final View fakeInsideView = findViewById(R.id.fake_inside_view);
    final HorizontalScrollView fakeHorizontalSv = findViewById(R.id.fake_horizontal_scroll_view);

    realHorizontalSv.setOnScrollChangeListener(new View.OnScrollChangeListener() {
        @Override
        public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
            fakeInsideView.setMinimumWidth(realInsideView.getWidth());
            fakeHorizontalSv.setScrollX(scrollX);
        }
    });