Android Studio CoordinatorLayout& RecyclerView空白? [英] android studio CoordinatorLayout & RecyclerView blank?
问题描述
运行我的应用程序时，我得到一个空的活动，暂时我只有一个列表，应该通过从JSON读取这些图像地址以及从logcat中读取这些图像的地址来投影图像，我可以看到这些地址已传递给该应用程序，并记录下来，但不确定为什么布局没有结构化，而我却得到了空白的空白屏幕.
Runing my app i get a blank activity, for the time being i only have a list which should be projecting images, by reading these images addresses from JSON, and from the logcat i could see the the addresses being passed to the app, and logged, but not sure why the layout is not getting structured and i get a blank white screen.
使用Genymotion-android s6-android studio 2.1.1
Using Genymotion - android s6 - android studio 2.1.1
MyActivity;
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;
activity_main.xml;
<?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;
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;
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;
}
}
解决错误，我得到了跟进；
going over the error i got the followin;
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; 而且我已经在stackoverflow上搜索了未实现的eglSurfaceAttrib
DataAdapter.java; and i have searched stackoverflow for eglSurfaceAttrib not implemented
增加了仿真器磁盘的大小，实现了Gapp以及我在以下文章中发现的其他说明； Android Studio-仿真器-eglSurfaceAttrib未实现
increased the emulator disk size, implemented Gapp and other instructions i found on the following posts; Android Studio - Emulator - eglSurfaceAttrib not implemented
但仍然没有布局.
正如下面的用户所建议的，我将initView的初始化更改为ImageAddresses的末尾，以使其遵循检索地址的步骤，并记录了android_version.size();.会返回零，因此布局仍为空白，但不确定如何解决此问题，
As the user below suggested, i changed the initialization of initView, into the end of ImageAddresses, in order for it to follow the step of retrieving the addresses, and also logged the android_version.size(); which returns zero, thus the layout is still blank but not sure how to fix this problem,
更改后的Logcat；
Logcat after changes ;
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，此错误的原因是执行方法的时间冲突，因此，正如您所建议的那样，我正在尝试使用runOnUiThread，我不确定如何在我的代码中正确构建，到目前为止，我已经尝试过我的MainActivity中的以下内容；
Apparently the cause of this error is a conflict in timing in executing methods, thus as suggested by of you i am trying to user runOnUiThread, which i am not sure how to construct properly within my code, so far i've tried the following in my MainActivity;
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);
//私有最终字符串android_image_urls [] = 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，因为该应用程序仍会崩溃-并且出现以下错误；
} But i guess it is not the right way to do it, since the app still crash - and i get the following errors;
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)
推荐答案
在ImagesAddresses();中，您使用Firebase从Web服务中检索数据，然后通过委托方法获得结果.
onDataChange.由于此方法的执行是异步的，因此发生的情况是在调用onDataChange之前先调用initViews();并因此调用prepareData().如您所见，图像android_image_urls仍然为空.您需要做的就是从onDataChange调用initViews();，确保initViews();在UI Thread上运行.
In ImagesAddresses(); you are using Firebase to retrieve the data from your webservice, and you get the results through the delegate method
onDataChange. Since the execution of this method is asynchronous, what happens is that initViews(); and, therefore prepareData(), are called before onDataChange is called. As you can image android_image_urls is still empty. What you have to do to fix is to call initViews(); from onDataChange, making sure that it, initViews();, runs on the UI Thread.
这篇关于Android Studio CoordinatorLayout& RecyclerView空白?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
