运行我的应用程序我得到一个空白活动，暂时我只有一个列表应该是投影图像，通过从JSON读取这些图像地址，从logcat我可以看到传递给应用程序的地址，并记录，但不知道为什么布局没有结构化，我得到一个空白的白色屏幕。
使用Genymotion - android s6 - android studio 2.1.1
MyActivity;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
public class MainActivity extends AppCompatActivity {
ArrayList<String> image_urls = new ArrayList<String>();
String[] android_image_urls = new String[image_urls.size()];
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Firebase.setAndroidContext(this);
ImagesAddresses();
initViews();
}
public void ImagesAddresses(){
Firebase ref = new Firebase("https://xxxxx.firebaseio.com/xxxxxx/xxx");
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
Map<String, String> allADR = (HashMap<String, String>) snapshot.getValue();
if (allADR != null) {
Collection<String> BlkADR = allADR.values();
image_urls.addAll(BlkADR);
android_image_urls = image_urls.toArray(android_image_urls);
Log.i("myTag", image_urls.toString());
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
}
private void initViews(){
RecyclerView recyclerView = (RecyclerView)findViewById(R.id.card_recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(layoutManager);
ArrayList androidVersion = prepareData();
DataAdapter adapter = new DataAdapter(getApplicationContext(),androidVersion);
recyclerView.setAdapter(adapter);
}
private ArrayList prepareData(){
ArrayList android_version = new ArrayList<>();
for(int i=0;i<android_image_urls.length;i++){
AndroidVersion androidVersion = new AndroidVersion();
androidVersion.setAndroid_image_url(android_image_urls[i]);
android_version.add(androidVersion);
}
return android_version;
}
}
activity_main.xml中;
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.v7.widget.RecyclerView
android:id="@+id/card_recycler_view"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</android.support.design.widget.CoordinatorLayout>
DataAdapter.java;
package net.janusjanus.interactive_layout;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {
private ArrayList<AndroidVersion> android_version;
private Context context;
public DataAdapter(Context context,ArrayList<AndroidVersion> android_version) {
this.context = context;
this.android_version = android_version;
}
@Override
public DataAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.row_layout, viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, int i) {
Picasso.with(context).load(android_version.get(i).getAndroid_image_url()).resize(120, 60).into(viewHolder.img_android);
}
@Override
public int getItemCount() {
return android_version.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
ImageView img_android;
public ViewHolder(View view) {
super(view);
img_android = (ImageView)view.findViewById(R.id.img_android);
}
}
}
AndroidVersion.java;
package net.janusjanus.interactive_layout;
public class AndroidVersion {
private String android_image_url;
public String getAndroid_image_url() {
return android_image_url;
}
public void setAndroid_image_url(String android_image_url) {
this.android_image_url = android_image_url;
}
}
重复错误我得到了跟随;
05-15 04:19:57.942 7827-7875/net.janusjanus.interactive_layout I/OpenGLRenderer: Initialized EGL, version 1.4
05-15 04:19:58.055 7827-7875/net.janusjanus.interactive_layout W/EGL_emulation: eglSurfaceAttrib not implemented
05-15 04:19:58.056 7827-7875/net.janusjanus.interactive_layout W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xe7d65fe0, error=EGL_SUCCESS
05-15 04:20:01.188 7827-7827/net.janusjanus.interactive_layout I/myTag: [http://res.cloudinary.com/xxxxx/image/xxxxxx/xxxxxx/fw88v6xu6wybamg9zzt6.jpg, http://res.cloudinary.com/xxxx/image/upload/xxxxx/xxxxdgfddd.jpg, http://res.cloudinary.com/xxxxxxx/jjjjjj/upload/xxxxxxxx/vvvghgggggg.jpg]
DataAdapter.java; 我已经搜索了stackoverflow for eglSurfaceAttrib未实现
增加了模拟器磁盘大小，实现了Gapp和我在以下帖子中找到的其他说明; Android Studio - Emulator - eglSurfaceAttrib not implemented
但仍然没有布局。
正如下面的用户建议的那样，我将initView的初始化更改为ImageAddresses的末尾，以便它遵循检索地址的步骤，并且还记录了android_version.size（）;返回零，因此布局仍然是空白但不确定如何解决此问题，
更改后的Logcat;
05-15 05:59:25.025 3473-3537/net.janusjanus.interactive_layout I/OpenGLRenderer: Initialized EGL, version 1.4
05-15 05:59:25.174 3473-3537/net.janusjanus.interactive_layout W/EGL_emulation: eglSurfaceAttrib not implemented
05-15 05:59:25.174 3473-3537/net.janusjanus.interactive_layout W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xe08c47a0, error=EGL_SUCCESS
05-15 05:59:25.253 3473-3473/net.janusjanus.interactive_layout I/myTag: 0
05-15 05:59:25.253 3473-3473/net.janusjanus.interactive_layout I/myTag: 0
05-15 05:59:25.655 3473-3473/net.janusjanus.interactive_layout I/myTag: 0
05-15 05:59:25.656 3473-3473/net.janusjanus.interactive_layout I/myTag: 0
05-15 05:59:25.656 3473-3473/net.janusjanus.interactive_layout I/myTag: 0
显然，这个错误的原因是执行方法的时间冲突，因此正如你所建议我尝试使用runOnUiThread，我不知道如何在我的代码中正确构建，到目前为止，我是＆＃39;我在我的MainActivity中尝试了以下内容;
public class MainActivity extends AppCompatActivity {
ArrayList<String> image_urls = new ArrayList<String>();
String[] android_image_urls = new String[image_urls.size()];
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Firebase.setAndroidContext(this);
ImagesAddresses();
}
public void ImagesAddresses(){
Firebase ref = new Firebase("https://xxxxx.firebaseio.com/xxxxx/xxxxx");
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
Map<String, String> allADR = (HashMap<String, String>) snapshot.getValue();
if (allADR != null) {
Collection<String> BlkADR = allADR.values();
image_urls.addAll(BlkADR);
android_image_urls = image_urls.toArray(android_image_urls);
// private final String android_image_urls [] = android_image_urls
Log.i("myTag", image_urls.toString());
initViews();
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
}
private void initViews(){
runOnUiThread(new Runnable() {
public void run() {
//Do something on UiThread
RecyclerView recyclerView = (RecyclerView)findViewById(R.id.card_recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(layoutManager);
ArrayList androidVersion = prepareData();
DataAdapter adapter = new DataAdapter(getApplicationContext(),androidVersion);
recyclerView.setAdapter(adapter);
}
});
}
private ArrayList prepareData(){
ArrayList android_version = new ArrayList<>();
for(int i=0;i<android_image_urls.length;i++){
AndroidVersion androidVersion = new AndroidVersion();
androidVersion.setAndroid_image_url(android_image_urls[i]);
android_version.add(androidVersion);
}
return android_version;
}
} 但我想这不是正确的方法，因为应用程序仍然崩溃 - 我得到以下错误;
05-15 07:11:34.935 11327-11327/net.janusjanus.interactive_layout E/AndroidRuntime: FATAL EXCEPTION: main
Process: net.janusjanus.interactive_layout, PID: 11327
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()' on a null object reference
at android.support.v7.widget.RecyclerView.computeVerticalScrollRange(RecyclerView.java:1654)
at android.view.View.onDrawScrollBars(View.java:13924)
at android.view.View.onDrawForeground(View.java:17657)
at android.view.View.draw(View.java:16189)
at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3097)
at android.view.View.updateDisplayListIfDirty(View.java:15174)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.support.design.widget.CoordinatorLayout.drawChild(CoordinatorLayout.java:1077)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.draw(View.java:16181)
at android.view.View.updateDisplayListIfDirty(View.java:15174)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15169)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15169)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15169)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.updateDisplayListIfDirty(View.java:15169)
at android.view.View.draw(View.java:15948)
at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
at android.view.View.draw(View.java:16181)
at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2690)
at android.view.View.updateDisplayListIfDirty(View.java:15174)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:281)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:287)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:322)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2615)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2434)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2067)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
答案 0 :(得分：1)
在ImagesAddresses();中，您正在使用Firebase从您的网络服务中检索数据，并通过委托方法获得结果
onDataChange。由于此方法的执行是异步的，因此在调用initViews();之前调用prepareData()，因此调用onDataChange。因为你可以成像android_image_urls仍然是空的。您要解决的问题是从initViews();致电onDataChange，确保initViews();在UI Thread上运行。