使用 RecyclerView 添加到 GridLayout 的动态按钮相互叠加
Dynamic buttons added to a GridLayout using RecyclerView are added on top of each other
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，并且布局必须自行更新以使按钮成行。 我的问题是，当添加一个新按钮时，它会出现在最后添加的按钮之上，并且没有按行格式放置。在下面的这张图片中，我展示了我想要的和我想要的目前正在发生，标有数字的方块是我的按钮。在我的图像中，我在布局中添加了 6 个按钮，但它们都在彼此之上。
我四处寻找如何做到这一点，有人建议我使用 RecyclerView 和 GridLayoutManager。我已将此添加到我的代码中，但正如我所说 问题是当我添加一个按钮时，如果我添加另一个按钮，第二个按钮将添加到第一个按钮之上。 如果我的按钮是预设的，我所拥有的就可以使用，但对于动态按钮则不行。
这是我的代码：
主片段启动 RecyclerView。我有另一个 activity 启动 createButton() 方法并传递 drawable 和 String。这些可绘制对象和字符串根据用户的操作一次一个地传递给此方法，并一次一个地创建一个图像按钮。
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>
编辑
这是我更新的 MyFragment 代码
现在我在添加第二个 ImageButton 时收到 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();
}
}
我的应用程序在创建第二个按钮时崩溃时出现的错误：
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)
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))
}
}
并在适配器中添加此方法
public void addItem(int position) {
list.add(position);
notifyItemInserted(position);
notifyItemRangeChanged(position, list.size());
}
编辑
为防止出现警告，请尝试将您的适配器初始化移动到 onCreate
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
List<ItemObject> myList = new ArrayList<ItemObject>();
rcAdapter = new RecyclerViewAdapter(getActivity(), myList);
}
创建按钮时，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这些操作。您也不需要创建或设置任何新的适配器或布局管理器。
在您的情况下，您将向适配器 class 持有的列表中添加一个元素，然后可能会在适当的位置调用 notifyItemInserted()。您可以通过向适配器添加一个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>
注意 -large，它将通知系统此尺寸及以上尺寸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);
我提到这个是因为屏幕尺寸桶（-large）可能不是确定列数的最佳方式。您可能更适合使用屏幕宽度限定符（例如 -w600dp），它会在设备旋转时更新（而在这种情况下尺寸桶不会改变）。您可以阅读有关资源限定符的更多信息 here.
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，并且布局必须自行更新以使按钮成行。 我的问题是，当添加一个新按钮时，它会出现在最后添加的按钮之上，并且没有按行格式放置。在下面的这张图片中，我展示了我想要的和我想要的目前正在发生，标有数字的方块是我的按钮。在我的图像中，我在布局中添加了 6 个按钮，但它们都在彼此之上。
我四处寻找如何做到这一点，有人建议我使用 RecyclerView 和 GridLayoutManager。我已将此添加到我的代码中，但正如我所说 问题是当我添加一个按钮时，如果我添加另一个按钮，第二个按钮将添加到第一个按钮之上。 如果我的按钮是预设的，我所拥有的就可以使用，但对于动态按钮则不行。
这是我的代码：
主片段启动 RecyclerView。我有另一个 activity 启动 createButton() 方法并传递 drawable 和 String。这些可绘制对象和字符串根据用户的操作一次一个地传递给此方法，并一次一个地创建一个图像按钮。
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>
编辑
这是我更新的 MyFragment 代码 现在我在添加第二个 ImageButton 时收到 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();
}
}
我的应用程序在创建第二个按钮时崩溃时出现的错误：
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)
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))
}
}
并在适配器中添加此方法
public void addItem(int position) {
list.add(position);
notifyItemInserted(position);
notifyItemRangeChanged(position, list.size());
}
编辑
为防止出现警告，请尝试将您的适配器初始化移动到 onCreate
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
List<ItemObject> myList = new ArrayList<ItemObject>();
rcAdapter = new RecyclerViewAdapter(getActivity(), myList);
}
创建按钮时，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这些操作。您也不需要创建或设置任何新的适配器或布局管理器。
在您的情况下，您将向适配器 class 持有的列表中添加一个元素，然后可能会在适当的位置调用 notifyItemInserted()。您可以通过向适配器添加一个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>
注意 -large，它将通知系统此尺寸及以上尺寸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);
我提到这个是因为屏幕尺寸桶（-large）可能不是确定列数的最佳方式。您可能更适合使用屏幕宽度限定符（例如 -w600dp），它会在设备旋转时更新（而在这种情况下尺寸桶不会改变）。您可以阅读有关资源限定符的更多信息 here.