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

Question

我的应用程序的主要活动有一个自定义列表，每个列表项都应该在向左滑动时显示一个与之关联的操作按钮，并在同一个列表项再次向右滑动时隐藏该按钮。现在我试图通过创建 Swipe 检测器类然后将其设置为 ItemHolder 类中列表项的触摸侦听器来检测每个列表项的滑动事件。

但是，由于 RecyclerView 是可滚动的，因此无法检测到对单个列表项的滑动。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);
}

滑动检测适用于除 RecyclerView 的列表项（或任何其他可滚动视图的子项）之外的任何其他视图。如何检测列表项上的滑动？

标签： androidandroid-recyclerviewswipe

Answer 1

问题已解决，但我不知道这是否是正确的方法，但它确实有效。事情是这样的——

使用两个方法创建一个接口SwipeActions，用于左右滑动的回调。

滑动动作

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

然后提到SwipeAction作为 SwipeDetector 的属性之一，然后在构造函数中初始化它。

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，该参数将在MainActivity中用于检索执行滑动的子视图的对象。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);
}

另外，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);
}