Question

我想将动态按钮添加到网格布局，如下所示。 每个按钮一次添加一个，布局必须自行更新以使按钮成行。 我的问题是，当添加新按钮时，它会显示在添加的最后一个按钮的顶部，并且不会以行格式显示。在下图中，我显示了我想要的内容以及当前正在发生的内容，标有数字的方块是我的按钮。在我所拥有的图像中，我在布局中添加了6个按钮，但它们都是相互叠加的。

我已经了解了如何执行此操作，并建议我使用RecyclerView和GridLayoutManager。我已将此添加到我的代码中，但就像我说问题是当我添加一个按钮，然后如果我添加另一个按钮，第二个添加在第一个按钮之上。我是什么如果我的按钮是预设的，则有效，但不适用于动态按钮。

这是我的代码：

Main Fragment启动RecyclerView。我有另一个活动启动createButton()方法并传递 drawable 和 String 。这些drawable和字符串将根据用户的操作一次一个地传递给此方法，并一次创建一个图像按钮。

public class MyFragment extends Fragment {

    private GridLayoutManager lLayout;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    // onCreateView
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.my_fragment, container, false);

        // Get screen size to have different layouts for phone and tablet
        int screenSize = getResources().getConfiguration().screenLayout &
                Configuration.SCREENLAYOUT_SIZE_MASK;

        String toastMsg;
        switch (screenSize) {
            case Configuration.SCREENLAYOUT_SIZE_LARGE:
                toastMsg = "Large screen";
                Log.d("tag_name", "Large screen");
                break;
            case Configuration.SCREENLAYOUT_SIZE_NORMAL:
                toastMsg = "Normal screen";
                Log.d("tag_name", "Normal screen");
                break;
            case Configuration.SCREENLAYOUT_SIZE_SMALL:
                toastMsg = "Small screen";
                Log.d("tag_name", "Small screen");
                break;
            default:
                toastMsg = "Screen size is neither large, normal or small";
                Log.d("tag_name", "Screen size is not large, normal, or small");
        }
        Toast.makeText(getActivity(), toastMsg, Toast.LENGTH_LONG).show();

        // Create an empty list to initialize the adapter (or else get nullPointerException error)
        List<ItemObject> myList = new ArrayList<ItemObject>();

        // 3 rows for tablet
        // 2 rows for phone

        if (screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE
                || screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE) {
            lLayout = new GridLayoutManager(getActivity(), 3, GridLayoutManager.HORIZONTAL, false);
        } else
            lLayout = new GridLayoutManager(getActivity(), 2, GridLayoutManager.HORIZONTAL, false);

        RecyclerView rView = (RecyclerView) view.findViewById(R.id.recycler_view);

        rView.setHasFixedSize(true);
        rView.setLayoutManager(lLayout);

        RecyclerViewAdapter rcAdapter = new RecyclerViewAdapter(getActivity(), myList);
        rView.setAdapter(rcAdapter);

        return view;
    }

    private List<ItemObject> getAllItemList(String applicationName, Drawable app_drawable) {

        List<ItemObject> allItems = new ArrayList<ItemObject>();
        allItems.add(new ItemObject(applicationName, app_drawable));

        return allItems;
    }

    public void createButton(Drawable d, String appName) {

        List<ItemObject> rowListItem = getAllItemList(appName, d);
        lLayout = new GridLayoutManager(getActivity(), 2, GridLayoutManager.HORIZONTAL, false);


        RecyclerView rView = (RecyclerView) getView().findViewById(R.id.recycler_view);
        rView.setHasFixedSize(true);
        rView.setLayoutManager(lLayout);

        RecyclerViewAdapter rcAdapter = new RecyclerViewAdapter(getActivity(), rowListItem);
        rView.setAdapter(rcAdapter);

    }

}

我的布局（my_fragment）：

<LinearLayout android:id="@+id/my_fragment"
          xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:layout_marginTop="15dp"
          android:gravity="center_horizontal">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:scrollbars="horizontal"/>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageButton
            android:id="@+id/new_app_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <TextView
            android:id="@+id/new_app_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/new_app_button"
            android:gravity="center"/>

    </RelativeLayout>
</LinearLayout>

修改

这是MyFragment的更新代码 现在，当第二个ImageButton被添加时，我得到一个nullPointerException

public class MyFragment extends Fragment {

private GridLayoutManager lLayout;

private ButtonCreator bc;
RecyclerViewAdapter rcAdapter;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    List<ItemObject> myList = new ArrayList<ItemObject>();
    rcAdapter = new RecyclerViewAdapter(getActivity(),myList);

}

// onCreateView
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.home_fragment, container, false);


    // Get screen size so we can have different layouts for phone and tablet
    int screenSize = getResources().getConfiguration().screenLayout &
            Configuration.SCREENLAYOUT_SIZE_MASK;

    String toastMsg;
    switch(screenSize) {
        case Configuration.SCREENLAYOUT_SIZE_LARGE:
            toastMsg = "Large screen";
            Log.d("tag_name", "Large screen");
            break;
        case Configuration.SCREENLAYOUT_SIZE_NORMAL:
            toastMsg = "Normal screen";
            Log.d("tag_name", "Normal screen");
            break;
        case Configuration.SCREENLAYOUT_SIZE_SMALL:
            toastMsg = "Small screen";
            Log.d("tag_name", "Small screen");
            break;
        default:
            toastMsg = "Screen size is neither large, normal or small";
            Log.d("tag_name", "Screen size is not large, normal, or small");
    }
    Toast.makeText(getActivity(), toastMsg, Toast.LENGTH_LONG).show();


    // Create an empty list to initialize the adapter (or else get nullPointerException error)

    if (screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE
    || screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE) {
        lLayout = new GridLayoutManager(getActivity(), 3, GridLayoutManager.HORIZONTAL, false);
    }

    else lLayout = new GridLayoutManager(getActivity(), 2, GridLayoutManager.HORIZONTAL, false);


    RecyclerView rView = (RecyclerView)view.findViewById(R.id.recycler_view);

    rView.setHasFixedSize(true);
    rView.setLayoutManager(lLayout);


    rView.setAdapter(rcAdapter);


    return view;
}

private List<ItemObject> getAllItemList(String applicationName, Drawable app_drawable){

    List<ItemObject> allItems = new ArrayList<ItemObject>();
    allItems.add(new ItemObject(applicationName, app_drawable));


    return allItems;
}


public void createButton (Drawable d, String appName){

    rcAdapter.addItem(new ItemObject(appName , d));

}



// In order to get the view of HomeFragment correctly

public interface ButtonCreator{
    void buttonCreator(Drawable d, String string);
}



@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    bc = (ButtonCreator) activity;
}

}

我如何在MyFragment中调用createButton方法（在runOnUiThread方法中调用）

public class MainActivity extends FragmentActivity implements MyFragment.ButtonCreator {


private Thread repeatTaskThread;
private byte[] byteArray;

@Override
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

   FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
   ft.replace(R.id.container, new MyFragment()).commit();
}


public void buttonCreator(Drawable d,String a) {
    MyFragment homeFragment = (MyFragment)getSupportFragmentManager().getFragments().get(1);
    homeFragment.createButton(d, a);
}

public void RepeatTask(){

     repeatTaskThread = new Thread() {
        public void run() {
           while (true) {


              try {


                 System.out.println("TRY_1");

                 Socket socket = new Socket("192.168.0.26", 5050);

                 // Get data sent through socket
                 DataInputStream DIS = new DataInputStream(socket.getInputStream());

                 System.out.println("DataInputStream Started");

                 // read data that got sent
                 final String applicationName = DIS.readUTF();


                 // read array data for bitmap

                 int len = DIS.readInt();
                 byte[] data = new byte[len];

                 DIS.readFully(data, 0, data.length);


                 Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
                 final Drawable d = new BitmapDrawable(getResources(), bitmap);


                  runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                       // TODO Auto-generated method stub


                       Log.d("tag_name", "Try_2");

                        buttonCreator(d,applicationName);


                    }
                 });


                 socket.close();




              } catch (Exception e) {


                 System.out.println("Exception is " + e.toString());

              }


              try {
                 // Sleep for 5 seconds
                 Thread.sleep(5000);
              } catch (Exception e) {
                 e.printStackTrace();
              }
           }
        }

        ;
     };
     repeatTaskThread.start();


}

}

我的应用在创建第二个按钮时崩溃时发生错误：

05-11 17:05:25.275 14257-14257/it.anddev.bradipao.janus E/RecyclerView: No adapter attached; skipping layout
05-11 17:05:25.275 14257-14257/it.anddev.bradipao.janus D/AndroidRuntime: Shutting down VM
05-11 17:05:25.275 14257-14257/it.anddev.bradipao.janus W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x437c0160)
05-11 17:05:25.305 14257-14257/it.anddev.bradipao.janus E/AndroidRuntime: FATAL EXCEPTION: main
                                                                      Process: it.anddev.bradipao.janus, PID: 14257
                                                                      java.lang.NullPointerException
                                                                          at android.support.v7.widget.RecyclerView.computeHorizontalScrollRange(RecyclerView.java:1518)
                                                                          at android.view.View.onDrawScrollBars(View.java:12248)
                                                                          at android.view.View.draw(View.java:14794)
                                                                          at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3171)
                                                                          at android.view.View.getDisplayList(View.java:13655)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.View.draw(View.java:14505)
                                                                          at android.view.ViewGroup.drawChild(ViewGroup.java:3134)
                                                                          at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2971)
                                                                          at android.view.View.getDisplayList(View.java:13650)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.View.draw(View.java:14505)
                                                                          at android.view.ViewGroup.drawChild(ViewGroup.java:3134)
                                                                          at android.support.v7.widget.RecyclerView.drawChild(RecyclerView.java:3693)
                                                                          at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2971)
                                                                          at android.view.View.draw(View.java:14791)
                                                                          at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3171)
                                                                          at android.view.View.getDisplayList(View.java:13655)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3108)
                                                                          at android.view.View.getDisplayList(View.java:13593)
                                                                          at android.view.View.getDisplayList(View.java:13697)
                                                                          at android.view.HardwareRenderer$GlRenderer.buildDisplayList(HardwareRenderer.java:1570)
                                                                          at android.view.HardwareRenderer$GlRenderer.draw(HardwareRenderer.java:1449)
                                                                          at android.view.ViewRootImpl.draw(ViewRootImpl.java:2476)
                                                                          at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2300)
                                                                          at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1929)
                                                                          at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1043)
                                                                          at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
                                                                          at android.view.Choreographer$CallbackRecord.run(Choreographer.java:771)
                                                                          at android.view.Choreographer.doCallbacks(Choreographer.java:574)
                                                                          at android.view.Choreographer.doFrame(Choreographer.java:544)
                                                                          at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:757)
                                                                          at android.os.Handler.handleCallback(Handler.java:733)
                                                                          at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                          at android.os.Looper.loop(Looper.java:149)
                                                                          at android.app.ActivityThread.main(ActivityThread.java:5257)
                                                                          at java.lang.reflect.Method.invokeNative(Native Method)
                                                                          at java.lang.reflect.Method.invoke(Method.java:515)
                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:788)
                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604)
                                                                          at dalvik.system.NativeStart.main(Native Method)

Answer 1

做这样的事情

public class MyFragment extends Fragment {

    private GridLayoutManager lLayout;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    // onCreateView
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.my_fragment, container, false);

        // Get screen size to have different layouts for phone and tablet
        int screenSize = getResources().getConfiguration().screenLayout &
                Configuration.SCREENLAYOUT_SIZE_MASK;

        String toastMsg;
        switch (screenSize) {
            case Configuration.SCREENLAYOUT_SIZE_LARGE:
                toastMsg = "Large screen";
                Log.d("tag_name", "Large screen");
                break;
            case Configuration.SCREENLAYOUT_SIZE_NORMAL:
                toastMsg = "Normal screen";
                Log.d("tag_name", "Normal screen");
                break;
            case Configuration.SCREENLAYOUT_SIZE_SMALL:
                toastMsg = "Small screen";
                Log.d("tag_name", "Small screen");
                break;
            default:
                toastMsg = "Screen size is neither large, normal or small";
                Log.d("tag_name", "Screen size is not large, normal, or small");
        }
        Toast.makeText(getActivity(), toastMsg, Toast.LENGTH_LONG).show();

        // Create an empty list to initialize the adapter (or else get nullPointerException error)

        // 3 rows for tablet
        // 2 rows for phone

        if (screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE
                || screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE) {
            lLayout = new GridLayoutManager(getActivity(), 3, GridLayoutManager.HORIZONTAL, false);
        } else
            lLayout = new GridLayoutManager(getActivity(), 2, GridLayoutManager.HORIZONTAL, false);

        RecyclerView rView = (RecyclerView) view.findViewById(R.id.recycler_view);

        rView.setHasFixedSize(true);
        rView.setLayoutManager(lLayout);

        rView.setAdapter(rcAdapter);

        return view;
    }

    RecyclerViewAdapter rcAdapter;

    private List<ItemObject> getAllItemList(String applicationName, Drawable app_drawable) {

        List<ItemObject> allItems = new ArrayList<ItemObject>();
        allItems.add(new ItemObject(applicationName, app_drawable));

        return allItems;
    }

    public void createButton(Drawable d, String appName) {

        rcAdapter.addItem(new ItemObject(appName , d))

    }

}

在适配器中添加此方法

public void addItem(int position) {
        list.add(position);
        notifyItemInserted(position);
        notifyItemRangeChanged(position, list.size());
    }

修改

要防止出现警告，请尝试将适配器初始化移至onCreate

@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); List<ItemObject> myList = new ArrayList<ItemObject>(); rcAdapter = new RecyclerViewAdapter(getActivity(), myList); }

Answer 2

创建按钮时，您只需要做两件事：

更新支持RecyclerView的数据结构适配器
使用适配器的notify...()方法之一通知适配器数据已更改（有several of them，使用最适用的方法）

您当前的代码似乎没有执行上述任何一项操作。您也不需要创建或设置任何新适配器或布局管理器。

在您的情况下，您将向适配器类所持的列表添加元素，然后可能使用适当的位置调用notifyItemInserted()。您可以通过向适配器添加方法来同时执行这两项操作：

public void addItem(ItemObject item) {
    mList.add(item);
    notifyItemInserted(mList.size() - 1);
}

不相关：在Android上，您可以使用资源解析系统来确定要显示的列数。

制作src/main/res/values/integers.xml并添加：

<resources>
    <integer name="grid_column_count">2</integer>
</resources>

制作src/main/res/values-large/integers.xml并添加：

<resources>
    <integer name="grid_column_count">3</integer>
</resources>

请注意 -large ，它将通知系统此大小及以上的屏幕应使用此备用资源值。现在在你的片段中你可以简单地写：

int columnCount = getResources().getInteger(R.integer.grid_column_count);
GridLayoutManager layout = new GridLayoutManager(getActivity(), columnCount, 
        GridLayoutManager.HORIZONTAL, false);

我之所以提到这一点，是因为屏幕大小存储桶（-large）可能不是确定列数的最佳方法。您可能更适合使用屏幕宽度限定符（例如-w600dp），如果设备旋转将更新（而大小桶在该方案中不会更改）。您可以阅读有关资源限定符here的更多信息。

使用RecyclerView添加到GridLayout的动态按钮会相互添加

2 个答案: