[Android] ScrollView detection by scrolling to the bottom and top

1. Source

Many paging components are inherited from ScrollView. to scroll to the bottom of a page, you need to check whether the page is scrolled to the top.

2. Code

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity" >    <ScrollView        android:id="@+id/scroll_view"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:scrollbars="vertical" >        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:background="@android:color/darker_gray"            android:orientation="vertical" >            <TextView                android:layout_width="wrap_content"                android:layout_height="2000dip"                android:text="text" />        </LinearLayout>    </ScrollView></RelativeLayout>

public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    final ScrollView view = (ScrollView) findViewById(R.id.scroll_view);    view.setOnTouchListener(new OnTouchListener() {        @Override        public boolean onTouch(View v, MotionEvent event) {            switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                break;            case MotionEvent.ACTION_MOVE:                if (v.getScrollY() <= 0) {                    Log.d("scroll view", "top");                } else if (view.getChildAt(0).getMeasuredHeight() <= v.getHeight() + v.getScrollY()) {                    Log.d("scroll view", "bottom");                    Log.d("scroll view", "view.getMeasuredHeight() = " + view.getMeasuredHeight()                        + ", v.getHeight() = " + v.getHeight()                        + ", v.getScrollY() = " + v.getScrollY()                        + ", view.getChildAt(0).getMeasuredHeight() = " + view.getChildAt(0).getMeasuredHeight());                }                break;            default:                break;            }            return false;} });    }}

3. Description

There are a lot of times to check for scrolling. Here we use MotionEvent. ACTION_MOVE of onTouch to detect rolling outside ScrollView. If it inherits ScrollView, it can be detected during other callbacks.

V. getScrollY () indicates the length of the scrollview. V. getHeight () indicates the height of the scrollview. View. getChildAt (0). getMeasuredHeight () is the height of the content. View. getMeasureHeight () cannot be used here ().

View. getMeasuredHeight () = 1038

V. getHeight () = 1038

V. getScrollY () = 2962

View. getChildAt (0). getMeasuredHeight () = 4000