Question

我有一个基本的布局设置：DrawerLayout，包含活动的主要布局和导航视图的布局。主要布局有一个CoordinatorLayout和所有必要的实现折叠工具栏功能，以及一个ViewPager，我稍后在代码中填充片段。片段的布局主要包括RecyclerView和其他次要视图。

问题如下：每当我向下滚动两个选项卡中的任意一个并滑动到新选项卡并返回到原始选项卡时，RecyclerView会收到onScrolled回调（它不应该因为我没有' t滚动RV本身，但ViewPager）具有负deltaY参数（这意味着方向向上），这导致顶部的下一个项目因此而进入可见性。

几点说明：

deltaY参数似乎总是等于下一个项目从顶部开始的高度（这给人的印象是RV会在整个过程发生时向上滚动一个项目）
我没有将OnPageChangeListener设置为ViewPager以获得通知每当页面滚动，选择或状态改变时。
我向片段的RecyclerView提供RecyclerViewScrollListener，以便在滚动RV以执行某些逻辑时获得通知（例如将此事件传播到活动以显示或隐藏浮动操作按钮）
调用onScrolled时，我已经制作了调用堆栈的屏幕截图。也许有人可能会发现它很有用。 Take a look。
我还制作了一段代表此行为的简短视频。 Take a look。
我在互联网上查了很多资源，但没有一个能帮助我解决这个问题。随意问任何问题。任何帮助将不胜感激。

dashboard_activity_layout.xml：

<?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:id="@+id/coordinatorLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appBarLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:elevation="@dimen/toolbar_shadow_height">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/toolbar_height"
            android:paddingTop="@dimen/toolbar_padding_top"
            app:layout_scrollFlags="scroll|enterAlwaysCollapsed"
            app:titleTextAppearance="@style/TitleTextView"
            tools:background="@color/colorPrimary"/>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent" 
            android:layout_height="@dimen/dashboard_activity_content_tab_layout_height"
            app:tabMode="fixed"
            app:tabGravity="fill"
            tools:background="@color/colorPrimary"/>

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

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:overScrollMode="never"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        tools:background="@color/colorPrimaryDark"/>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/actionButtonFab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/dashboard_activity_content_fab_margin"
        android:layout_gravity="bottom|end"
        android:src="@mipmap/ic_search_white_24dp"
        app:fabSize="normal"
        app:useCompatPadding="true"
        tools:backgroundTint="@color/colorAccent"/>

DashboardActivity.java（相关部分）：

private void initViewPager() {
    mViewPager = findViewById(R.id.viewPager);

    mAdapter = new DashboardViewPagerAdapter(getSupportFragmentManager());
    mAdapter.setViewPagerId(mViewPager.getId());
    mAdapter.setRecyclerViewStateListener(mRecyclerViewStateListener);

    populateAdapter();

    mViewPager.setAdapter(mAdapter);
    mViewPager.setOffscreenPageLimit(mAdapter.getCount());
}


private void populateAdapter() {
    BaseFragment baseFragment = mAdapter.getFragmentForPosition(TAB_TAB_1);

    if(baseFragment == null) {
        baseFragment = SomeFragment.newInstance(Common.SOME_TYPE_1);
    }

    mAdapter.addFragment(baseFragment);

    baseFragment = mAdapter.getFragmentForPosition(TAB_TAB_2);

    if(baseFragment == null) {
        baseFragment = SomeFragment.newInstance(Common.SOME_TYPE_2);
    }

    mAdapter.addFragment(baseFragment);

    baseFragment = mAdapter.getFragmentForPosition(TAB_TAB_3);

    if(baseFragment == null) {
        baseFragment = SomeOtherFragment.init();
    }

    mAdapter.addFragment(baseFragment);
}


private RecyclerViewStateListener mRecyclerViewStateListener = new RecyclerViewStateListener() {


    @Override
    public void onScrolledDownwards(RecyclerView recyclerView, int deltaY) {
        // Hiding the FAB by animating it
        DashboardCommon.hideActionButton(mActionButtonFab, mViewAnimator, true);
    }


    @Override
    public void onScrolledUpwards(RecyclerView recyclerView, int deltaY) {
        // Showing the FAB by animating it
        DashboardCommon.showActionButton(mActionButtonFab, mViewAnimator, true);
    }


};

SomeFragment.java（相关部分）：

private void initRecyclerView() {
    mRecyclerView = findViewById(R.id.recyclerView);
    mRecyclerView.addOnScrollListener(new RecyclerViewScrollListener(this));

    mLayoutManager = new LinearLayoutManager(
        getContext(),
        LinearLayoutManager.VERTICAL,
        false
    );
    mRecyclerView.setLayoutManager(mLayoutManager);

    mAdapter = new SomeRecyclerViewAdapter(getContext(), mItems);

    mRecyclerView.setAdapter(mAdapter);
}


// mRecyclerViewStateListener is the listener passed from the
// DashboardActivity


@CallSuper
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onScrollStateChanged(recyclerView, newState);
    }
}




@Override
public void onScrolled(RecyclerView recyclerView, int deltaX, int deltaY) {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onScrolled(recyclerView, deltaX, deltaY);
    }
}




@Override
public void onScrolledDownwards(RecyclerView recyclerView, int deltaY) {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onScrolledDownwards(recyclerView, deltaY);
    }
}




@Override
public void onScrolledUpwards(RecyclerView recyclerView, int deltaY) {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onScrolledUpwards(recyclerView, deltaY);
    }
}




@Override
public void onBottomReached() {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onBottomReached();
    }
}




@Override
public void onMidpointReached(int direction) {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onMidpointReached(direction);
    }
}




@Override
public void onTopReached() {
    if(mRecyclerViewStateListener != null) {
        mRecyclerViewStateListener.onTopReached();
    }
}

RecyclerViewScrollListener.java（相关部分）：

public class RecyclerViewScrollListener extends RecyclerView.OnScrollListener {


    public static final int DIRECTION_UNSPECIFIED = -1;
    public static final int DIRECTION_UPWARDS = 0;
    public static final int DIRECTION_DOWNWARDS = 1;

    // Omitted...

    private StateListener mStateListener;




    public RecyclerViewScrollListener(StateListener stateListener) {
        // Omitted..

        mStateListener = stateListener;
    }




    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        if(mStateListener != null) {
            mStateListener.onScrollStateChanged(recyclerView, newState);
        }
    }




    @Override
    public void onScrolled(RecyclerView recyclerView, int deltaX, int deltaY) {
        if(mStateListener != null) {
            mStateListener.onScrolled(recyclerView, deltaX, deltaY);
        }

        f(deltaY > 0) {
            // Recycler view's contents are moving downwards

            // Notifying about the downwards scroll
            if(mStateListener != null) {
                mStateListener.onScrolledDownwards(recyclerView, deltaY);
            }

            // Omitted...

            if(someConditionIsTrue) {
                // Omitted...

                // Notifying the listener
                mStateListener.onBottomReached();
            } else if((someOtherConditionIsTrue) {
                mStateListener.onMidpointReached(DIRECTION_DOWNWARDS);
            }
        } else if(deltaY < 0) {
            // Recycler view's contents are moving upwards

            // Notifying about upwards scroll
            if(mStateListener != null) {
                mStateListener.onScrolledUpwards(recyclerView, deltaY);
            }

            // Omitted...

            if(someConditionIsTrue) {
                // Omitted..

                // Notifying the listener
                mStateListener.onTopReached();
            } else if(someOtherConditionIsTrue) {
                mStateListener.onMidpointReached(DIRECTION_UPWARDS);
            }
        }
    }




    public interface StateListener {

        void onScrollStateChanged(RecyclerView recyclerView, int newState);

        void onScrolled(RecyclerView recyclerView, int deltaX, int deltaY);

        void onScrolledDownwards(RecyclerView recyclerView, int deltaY);

        void onScrolledUpwards(RecyclerView recyclerView, int deltaY);

        void onBottomReached();

        void onMidpointReached(int direction);

        void onTopReached();

    }




}

Answer 1

自动使用此卷轴一次

RecyclerView my_recycler_view= (RecyclerView) findViewById(R.id.my_recycler_view);
SnapHelper snapHelper = new PagerSnapHelper();
snapHelper.attachToRecyclerView(my_recycler_view);

快乐的编码干杯

Answer 2

希望会有所帮助

RecyclerView my_recycler_view= (RecyclerView) findViewById(R.id.my_recycler_view);

SnapHelper snapHelper = new PagerSnapHelper();

snapHelper.attachToRecyclerView(my_recycler_view);

Answer 3

即使我在2年前发布了这个问题，我还是决定提供答案。迟到总比没有好，对吧？

据我所知，问题在于RecyclerView项的布局具有TextView，其中包含android:textIsSelectable="true"属性。事实证明，通过删除该属性，问题消失了。您可能会问，我如何实现文本选择呢？老实说，我记得很久了。

无论如何，如果您遇到这样的问题，请尝试删除android:textIsSelectable="true"属性，它很可能会为您解决问题。

使用ViewPager

3 个答案: