android - 滑动以显示在 Android 中使用 RecyclerView 创建的列表上的操作按钮

Question

我的应用程序的主 Activity 有一个自定义列表，每个列表项应在向左滑动时显示与其关联的操作按钮，并在再次向右滑动同一列表项时隐藏该按钮。现在，我尝试通过创建滑动检测器类来检测每个列表项的滑动事件，然后将其设置为 ItemHolder 类中列表项的触摸监听器。

但是，由于 RecyclerView 是可滚动的，因此无法检测到单个列表项上的滑动。如何检测对单个列表项的滑动？

MainActivity - onCreate()

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_recycler);

    ArrayList<Subject> subjects = new ArrayList<>();

    subjects.add(new Subject(1, "Physics"));
    subjects.add(new Subject(2, "Chemistry"));
    subjects.add(new Subject(3, "Biology"));

    RecyclerView recyclerView = (RecyclerView) findViewById(R.id.subject_recycler_list_view);
    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
    SubjectRecyclerListAdapter adapter = new SubjectRecyclerListAdapter(getApplicationContext(), R.layout.row_layout , subjects);

    recyclerView.setAdapter(adapter);
    recyclerView.setLayoutManager(layoutManager);
}

滑动检测器

public class SwipeDetector implements View.OnTouchListener {
    static final int MIN_DISTANCE = 50;
    private float downX, downY, upX, upY;

    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                downX = event.getX();
                downY = event.getY();
                //   return true;
            }
            case MotionEvent.ACTION_UP: {
                upX = event.getX();
                upY = event.getY();

                float deltaX = downX - upX;
                float deltaY = downY - upY;

                // swipe horizontal?
                if ( Math.abs(deltaX) > MIN_DISTANCE){
                    // left or right
                    if ( deltaX < 0){
                        Log.i("Swipe Detector","LeftToRightSwipe!");
                        return true;
                    }
                    if ( deltaX > 0){
                        Log.i("Swipe Detector","RightToLeftSwipe!");
                        return true;
                    }
                } else{
                    Log.i("Swipe Detector","Swipe was only " + Math.abs(deltaX) + " long, need at least " + MIN_DISTANCE);
                }
            }
        }

        return false;
    }
}

itemHolder - 构造函数

public SubjectHolder(Context context, View itemView) {
    super(itemView);

    this.subjectTextView = (TextView) itemView.findViewById(R.id.name);

    SwipeDetector swipeDetector = new SwipeDetector();
    itemView.setOnTouchListener(swipeDetector);
}

滑动检测适用于任何其他 View ，除了 RecyclerView 的列表项(或任何其他可 ScrollView 的 subview )。如何检测列表项上的滑动？

Answer 1

问题解决了，但我不知道这样做是否正确，但它确实有效。事情是这样的——

创建一个接口(interface) SwipeActions，其中包含两个方法，用于左右滑动的回调。

滑动操作

public interface SwipeActions {
    public void onLeftSwipe(MotionEvent e);
    public void onRightSwipe(MotionEvent e);
}

然后将 SwipeAction 作为 SwipeDetector 的属性之一提及，然后在构造函数中将其初始化。

public class SwipeDetector implements View.OnTouchListener {
    static final int MIN_DISTANCE = 50;
    private float downX, downY, upX, upY;
    public SwipeActions swipeActions;

    public SwipeDetector(SwipeActions swipeActions) {
        this.swipeActions = swipeActions;
    }

    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                downX = event.getX();
                downY = event.getY();
            }
            case MotionEvent.ACTION_UP: {
                upX = event.getX();
                upY = event.getY();

                float deltaX = downX - upX;
                float deltaY = downY - upY;

                if ( Math.abs(deltaX) > MIN_DISTANCE){
                    if ( deltaX < 0){
                        swipeActions.onRightSwipe(event);
                        return true;
                    }
                    if ( deltaX > 0){
                        swipeActions.onLeftSwipe(event);
                        return true;
                    }
                } else{
                    Log.i("Swipe Detector","Swipe was only " + Math.abs(deltaX) + " long, need at least " + MIN_DISTANCE);
                }
            }
        }

        return false;
    }
}

Swipe Actions 将 MotionEvent 对象作为参数，该对象将在 MainActivity 中用于检索 subview 的对象滑动被执行。所以将 MainActivity 修改为这个 -

MainActivity - onCreate

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_recycler);

    ArrayList<Subject> subjects = new ArrayList<>();

    subjects.add(new Subject(1, "Physics"));
    subjects.add(new Subject(2, "Chemistry"));
    subjects.add(new Subject(3, "Biology"));

    RecyclerView recyclerView = (RecyclerView) findViewById(R.id.subject_recycler_list_view);

    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
    SubjectRecyclerListAdapter adapter = new SubjectRecyclerListAdapter(getApplicationContext(), R.layout.row_layout , subjects);
    SwipeDetector swipeDetector = new SwipeDetector(new SwipeActions() {
        @Override
        public void onLeftSwipe(MotionEvent evnt) {
            View childView = recyclerView.findChildViewUnder(evnt.getX(), evnt.getY());
            if(childView != null) {
                // Perform your action on childView (Swiped List Item)
            }
            else {
                Log.i("Main Recycler Activity", "Child View is Null");
            }
        }

        @Override
        public void onRightSwipe(MotionEvent evnt) {
            View childView = recyclerView.findChildViewUnder(evnt.getX(), evnt.getY());
            if(childView != null) {
                if(swipedViews.contains(childView)) {
                    // Perform your action on childView (Swiped List Item)
                }
            }
            else {
                Log.i("Main Recycler Activity", "Child View is Null");
            }
        }
    });

    recyclerView.setOnTouchListener(swipeDetector);
    recyclerView.setAdapter(adapter);
    recyclerView.setLayoutManager(layoutManager);
}

此外，我从 itemHolder 中删除了 TouchListener

itemHolder - 构造函数

public SubjectHolder(Context context, View itemView) {
    super(itemView);

    this.subjectTextView = (TextView) itemView.findViewById(R.id.name);
}