标签: android-recyclerview

我有一个RecyclerView垂直滚动的项目列表.每个列表项都包含精简模式下的Google Maps V2 MapView .我正在利用这个新功能返回位图,而不是一个完整的地图作为替代Google Static Maps API.

MapView的需要你打电话onCreate(),onResume(),onPause(),onDestroy()等从父活动/片段的相应的方法.在哪里RecyclerView.Adapter和/或RecyclerView.ViewHolder？

如何清理回收的MapView,以便内存不会泄漏,同时保持列表清空？

Google表示精简模式可用于列表:

...'精简模式'地图选项,非常适合您想要提供大量较小地图的情况,或者非常适合有意义的互动不切实际的地图,例如列表中的缩略图.

ListItem.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent">

    <com.google.android.gms.maps.MapView
        android:id="@+id/mapImageView"
        xmlns:map="http://schemas.android.com/apk/res-auto"
        android:layout_width="80dp"
        android:layout_height="100dp"
        map:liteMode="true"
        map:mapType="normal"
        map:cameraZoom="15"/>

<!-- ... -->

</RelativeLayout>

RecyclerView.Adapter和ViewHolder

public class NearbyStopsAdapter extends RecyclerView.Adapter<NearbyStopsAdapter.ViewHolder> {

    private final Context mContext;

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        MapView map;

        public ViewHolder(View view) {
            super(view);
            map = (MapView) view.findViewById(R.id.mapImageView);
            // Should …

当我将RecyclerView放在嵌套的scrollview中时,屏幕总是跳到RecyclerView的顶部而不是页面的顶部.这是一个简单的例子.

layout xml:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android">
<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="350dp"
            android:background="@android:color/holo_blue_dark"/>
        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycleView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>
</android.support.v4.widget.NestedScrollView>
</layout>

虚拟适配器的活动:

public class RecycleViewTestActivity extends AppCompatActivity {

public static class ExampleAdapter extends RecyclerView.Adapter<ExampleViewHolder> {

    private Context context;

    public ExampleAdapter(Context context) {
        this.context = context;
    }

    @Override
    public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        TextView view = new TextView(context);
        view.setText("Test");
        return new ExampleViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ExampleViewHolder holder, int position) {

    } …

我在我的应用程序中使用了RecyclerView支持,我看到了最奇怪的事情.在我触摸滚动之前,它不会显示任何项目.然后,突然之间,RecyclerView会自行填充.我已经确认填充了支持适配器的列表,并且在触摸事件之前永远不会调用onCreatViewHolder和onBindViewHolder.

以下是我设置recyclerview的方法:

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        Drawable divider = new ColorDrawable(ProfileInfo.getCurrentProfileColor());
        mInboxList.addItemDecoration(new DividerItemDecoration(getActivity(), divider, false));
        mInboxList.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
        mInboxList.setAdapter(new InboxAdapter(getActivity(), new ArrayList<Conversation>()));
        new AsyncTask<Void, Void, List<Conversation>{

              public List<Conversation> doInBackground(...){
                   //load the conversations
                   return conversations;
              }

              public void onPostExecute(List<Conversation> conversations){
                   ((InboxAdapter) mInboxList.getAdapter()).clear(false);
                   ((InboxAdapter) mInboxList.getAdapter()).addAll(conversations);

              }

        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     }

这是我的适配器的要点:

public class InboxAdapter extends RecyclerView.Adapter<InboxAdapter.ViewHolder> {
    List<Conversation> mConversations; //initialized in contructor

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = mInflater.inflate(R.layout.inbox_item, parent, false);
        ViewHolder holder …

我们如何知道用户是向下滚动还是向上滚动RecyclerView？

我尝试过RecyclerView#OnScrollListener,它给出了垂直滚动量和滚动状态.滚动状态空闲时,如何在开始拖动和滚动位置时获取最后一个滚动位置.

谢谢.

我试图从我RecyclerView的onRestart方法中删除所有元素,因此项目不会被加载两次:

@Override
protected void onRestart() {
    super.onRestart();

    // first clear the recycler view so items are not populated twice
    for (int i = 0; i < recyclerAdapter.getSize(); i++) {
        recyclerAdapter.delete(i);
    }

    // then reload the data
    PostCall doPostCall = new PostCall(); // my AsyncTask... 
    doPostCall.execute();
}

但由于某种原因,delete我在其中创建的方法adapter无法正常运行:

在RecyclerAdapter.java中:

public void delete(int position){
    myList.remove(position);
    notifyItemRemoved(position);
}

public int getSize(){
    return myList.size();
}

我认为列表中的每个其他项都会被删除而不是整个列表.

有一个listview它很容易,我只是打电话adapter.clear().

有人可以帮我修改一下代码吗？

我想我应该用,notifyItemRangeRemoved(...,...);但我不确定如何.TIA

如何创建选项菜单,如下面的屏幕截图所示:

单击RecyclerView项目的"更多"-Icon后,应打开选项菜单!

我的尝试是这样的:

@Override
public void onBindViewHolder(Holder holder, int position) {
    holder.txvSongTitle.setText(sSongs[position].getTitle());
    holder.txvSongInfo.setText(sSongs[position].getAlbum() + " - " + sSongs[position].getArtist());

holder.btnMore.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(mContext, "More...", Toast.LENGTH_SHORT).show();
        }
    });
}

但这会导致问题,因为如果我触摸RecyclerView项目更多按钮,则单击完整项目...

这是我的RecyclerViewOnTouchListener:

public class RecyclerViewOnTouchListener implements RecyclerView.OnItemTouchListener {
    private GestureDetector mGestureDetector;
    private OnTouchCallback mOnTouchCallback;

    public RecyclerViewOnTouchListener(Context context, final RecyclerView recyclerView, final OnTouchCallback onTouchCallback) {
        mOnTouchCallback = onTouchCallback;

        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onSingleTapUp(MotionEvent e) {
                return true;
            }

            @Override
            public void …

我正在试用RecyclerViewAndroid Lollipop中的新功能而且我被卡住了.

我正在尝试接收一个列表,其中包含图标和图标TextView右侧的列表Fragment.

我找到了关于如何设置的精彩教程RecyclerView.我遵循了每一点,只是改变了item_layout.xml我的需要.

该项目构建没有任何错误,但当它在我的设备上启动时,我收到此错误:

java.lang.RuntimeException:无法启动活动ComponentInfo {com.fredrikaldgard.materialcolors/com.fredrikaldgard.materialcolors.MainActivity}:java.lang.NullPointerException:尝试调用虚拟方法'void android.support.v7.widget.RecyclerView. setLayoutManager(android.support.v7.widget.RecyclerView $ LayoutManager)'对空对象引用

我试图谷歌问题,但我是Android开发的业余爱好者.

这是我的MainActivity:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // 1. get a reference to recyclerView
    RecyclerView recyclerView = (RecyclerView) findViewById(R.id.list);

    // 2. set layoutManger
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    // this is data fro recycler view
    ItemData itemsData[] = { new ItemData("Indigo",R.drawable.circle),
            new ItemData("Red",R.drawable.color_ic_launcher),
            new ItemData("Blue",R.drawable.indigo),
            new ItemData("Green",R.drawable.circle),
            new ItemData("Amber",R.drawable.color_ic_launcher),
            new ItemData("Deep Orange",R.drawable.indigo)};


    // 3. create …

我想隐藏/显示FloatingActionButton滚动RecyclerView.

我的XML布局:

<android.support.design.widget.CoordinatorLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent" >

            <android.support.v7.widget.RecyclerView
                android:id="@+id/recyclerview_eventlist"
                android:layout_width="match_parent"
                android:layout_height="match_parent" />

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab_createevent"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/fab_margin"
                app:layout_anchor="@id/recyclerview_eventlist"
                app:layout_anchorGravity="bottom|right|end"
                app:layout_behavior="com.eventizon.behavior.ScrollAwareFABBehavior"
                android:src="@drawable/ic_edit"
                app:backgroundTint="@color/custom_color_1"
                app:borderWidth="0dp" />
        </android.support.design.widget.CoordinatorLayout>

DrawerLayout是此布局的父布局.

    public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {


    private static final String TAG = "ScrollAwareFABBehavior";

    public ScrollAwareFABBehavior(Context context, AttributeSet attrs) {
        super();
        Log.e(TAG,"ScrollAwareFABBehavior");
    }

    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout,
            FloatingActionButton child, View target, int dxConsumed,
            int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
        // TODO Auto-generated method stub
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, …

我需要在recyclerview中检测滚动的开始/结束和方向.滚动侦听器有两种方法:onScrolled()和onScrollStateChanged().滚动开始后调用第一个方法(实际上是调用onScrolled()而不是onScrolling()).第二种方法提供有关状态的信息,但我没有方向信息.我怎样才能实现目标？

我发现了如何使用预览列表项

tools:listitem="@layout/my_item_layout"

但android studio正在将recyclerview预览为垂直列表.有没有办法告诉Android Studio我会附加一个水平,LinearLayoutManager以便它可以预览水平列表？