问题：
我收到以下错误：
java.lang.IllegalArgumentException：找不到可用的相机。
调用实例方法 ProcessCameraProvider.bindToLifecycle() 时。通过搜索“----- Code Crashes Here --------------”在下面的代码上下文中看到这一点。
问题：
如何防止此错误以及随后的应用程序崩溃？更具体地说，如何确保 CameraSelector 可以返回 Nexus 6 的相机实例？
假设
此调用中使用的 CameraSelector 似乎有问题。如果我在 bindToLifecycle 行上设置断点，并调试到该点并为 `cameraProvider.hasCamera(cameraSelector) 添加一个监视，它将返回 false。在调用 bindToLifecycle 方法之前，这可能不打算返回 true。如果是这样，我如何验证 cameraSelector 对象是否已成功创建（成功意味着它指向实际的相机对象）？
在创建 cameraSelector 对象时，我在构建器中使用了requireLensFacing方法，所以看起来 Nexus 6 硬件没有用这些 LENS_FACING_BACK 或 LENS_FACING_FRONT 标记任何东西，因此不返回任何相机实例？我理解正确吗？
我应该注意到，当在 Nexus 5 上运行完全相同的代码时，不会发生此错误，这就是为什么我倾向于认为这是一个硬件问题。
我也尝试了 LENS_FACING_FRONT int，但有同样的错误。如果我完全删除 requireLensFacing 构建组件，我会得到一个不同的错误：
java.util.NoSuchElementException
代码
package jp.oist.cameraxapp;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.camera.core.Camera;
import androidx.camera.core.CameraSelector;
import androidx.camera.core.ImageAnalysis;
import androidx.camera.core.ImageCapture;
import androidx.camera.core.ImageProxy;
import androidx.camera.core.Preview;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.camera.view.PreviewView;
import androidx.core.content.ContextCompat;
import androidx.lifecycle.LifecycleOwner;
import android.os.Bundle;
import android.util.Log;
import android.util.Size;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class MainActivity extends AppCompatActivity {
private ListenableFuture<ProcessCameraProvider> cameraProviderFuture;
private ExecutorService executor;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
executor = Executors.newSingleThreadExecutor();
PreviewView previewView = findViewById(R.id.previewView);
cameraProviderFuture = ProcessCameraProvider.getInstance(this);
cameraProviderFuture.addListener(() -> {
try {
// Camera provider is now guaranteed to be available
ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
// Set up the view finder use case to display camera preview
Preview preview = new Preview.Builder().build();
// Choose the camera by requiring a lens facing
CameraSelector cameraSelector = new CameraSelector.Builder()
.requireLensFacing(CameraSelector.LENS_FACING_BACK)
.build();
// Connect the preview use case to the previewView
preview.setSurfaceProvider(
previewView.createSurfaceProvider());
// Set up the capture use case to allow users to take photos
ImageCapture imageCapture = new ImageCapture.Builder()
.setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
.build();
ImageAnalysis imageAnalysis =
new ImageAnalysis.Builder()
.build();
imageAnalysis.setAnalyzer(executor, new ImageAnalysis.Analyzer() {
@Override
public void analyze(@NonNull ImageProxy image) {
int rotationDegrees = image.getImageInfo().getRotationDegrees();
Log.i("CameraXApp3", "Image Analyzed");
image.close();
}
});
// Attach use cases to the camera with the same lifecycle owner
// ------ Code Crashes Here --------------
Camera camera = cameraProvider.bindToLifecycle(
((LifecycleOwner) this),
cameraSelector,
preview,
imageCapture);
} catch (InterruptedException | ExecutionException e) {
// Currently no exceptions thrown. cameraProviderFuture.get() should
// not block since the listener is being called, so no need to
// handle InterruptedException.
}
}, ContextCompat.getMainExecutor(this));
}
}
围绕 IllegalArgumentException 的完整 logcat
2020-07-29 13:31:57.954 7345-7345/? E/Finsky: [2] VerifyPerSourceInstallationConsentInstallTask.b(2): Package name null is not an installed package
2020-07-29 13:31:59.660 462-877/? E/cutils: Failed to open(/data/misc/profiles/cur/0/jp.oist.cameraxapp/primary.prof): No such file or directory
2020-07-29 13:31:59.660 462-877/? E/installed: Failed to prepare /data/misc/profiles/cur/0/jp.oist.cameraxapp/primary.prof: No such file or directory
2020-07-29 13:31:59.661 729-756/? E/ArtManagerService: Failed to prepare profile for jp.oist.cameraxapp:/data/app/jp.oist.cameraxapp-HSYslGAf7kOyD4tEcVKEkw==/base.apk
2020-07-29 13:32:00.305 462-877/? E/installd: Failed to delete /data/app/vmdl841803495.tmp: No such file or directory
2020-07-29 13:32:00.846 729-729/? E/LoadedApk: Unable to instantiate appComponentFactory
java.lang.ClassNotFoundException: Didn't find class "androidx.core.app.CoreComponentFactory" on path: DexPathList[[],nativeLibraryDirectories=[/data/app/sk.baka.aedict3-FT98hpKmmu7AEcH7jl4_Lw==/lib/arm, /data/app/sk.baka.aedict3-FT98hpKmmu7AEcH7jl4_Lw==/base.apk!/lib/armeabi-v7a, /system/lib, /system/vendor/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:134)
at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.app.LoadedApk.createAppFactory(LoadedApk.java:226)
at android.app.LoadedApk.updateApplicationInfo(LoadedApk.java:338)
at android.app.ActivityThread.handleDispatchPackageBroadcast(ActivityThread.java:5441)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1740)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at com.android.server.SystemServer.run(SystemServer.java:500)
at com.android.server.SystemServer.main(SystemServer.java:322)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:839)
2020-07-29 13:32:00.847 729-729/? E/LoadedApk: Unable to instantiate appComponentFactory
java.lang.ClassNotFoundException: Didn't find class "androidx.core.app.CoreComponentFactory" on path: DexPathList[[],nativeLibraryDirectories=[/data/app/sk.baka.aedict3-FT98hpKmmu7AEcH7jl4_Lw==/lib/arm, /data/app/sk.baka.aedict3-FT98hpKmmu7AEcH7jl4_Lw==/base.apk!/lib/armeabi-v7a, /system/lib, /system/vendor/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:134)
at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.app.LoadedApk.createAppFactory(LoadedApk.java:226)
at android.app.LoadedApk.updateApplicationInfo(LoadedApk.java:338)
at android.app.ActivityThread.handleDispatchPackageBroadcast(ActivityThread.java:5441)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1740)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at com.android.server.SystemServer.run(SystemServer.java:500)
at com.android.server.SystemServer.main(SystemServer.java:322)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:839)
2020-07-29 13:32:02.251 11105-11105/jp.oist.cameraxapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: jp.oist.cameraxapp, PID: 11105
java.lang.IllegalArgumentException: No available camera can be found.
at androidx.camera.core.CameraSelector.filter(CameraSelector.java:100)
at androidx.camera.lifecycle.ProcessCameraProvider.bindToLifecycle(ProcessCameraProvider.java:389)
at androidx.camera.lifecycle.ProcessCameraProvider.bindToLifecycle(ProcessCameraProvider.java:275)
at jp.oist.cameraxapp.MainActivity.lambda$onCreate$0$MainActivity(MainActivity.java:80)
at jp.oist.cameraxapp.-$$Lambda$MainActivity$N0aObN0KVyRMowRsss_pmN8BZ44.run(Unknown Source:4)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6698)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:859)
2020-07-29 13:32:02.367 2459-9800/ch.deletescape.lawnchair.ci E/pe.lawnchair.c: Failed to open APK '/data/app/jp.oist.cameraxapp-bhz9WJnVll-cJYJKM51yGg==/base.apk' I/O error
2020-07-29 13:32:02.368 2459-9800/ch.deletescape.lawnchair.ci E/ResourcesManager: failed to add asset path /data/app/jp.oist.cameraxapp-bhz9WJnVll-cJYJKM51yGg==/base.apk
围绕 NoSuchElementException 的完整 logcat
2020-07-29 13:31:22.712 10962-10962/jp.oist.cameraxapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: jp.oist.cameraxapp, PID: 10962
java.util.NoSuchElementException
at java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:759)
at java.util.LinkedHashMap$LinkedKeyIterator.next(LinkedHashMap.java:780)
at androidx.camera.lifecycle.ProcessCameraProvider.bindToLifecycle(ProcessCameraProvider.java:415)
at androidx.camera.lifecycle.ProcessCameraProvider.bindToLifecycle(ProcessCameraProvider.java:275)
at jp.oist.cameraxapp.MainActivity.lambda$onCreate$0$MainActivity(MainActivity.java:79)
at jp.oist.cameraxapp.-$$Lambda$MainActivity$N0aObN0KVyRMowRsss_pmN8BZ44.run(Unknown Source:4)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6698)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:859)
2020-07-29 13:31:22.758 382-382/? E/lowmemorykiller: Error writing /proc/10962/oom_score_adj; errno=22
编辑1：
在 Nexus 6 上测试标准相机应用程序，发现它也崩溃了。这指出了评论者提出的 HAL 问题。重新启动 Nexus 6 以修复 HAL。现在 logcat 提出了一组全新的错误，但如果我不能自己解决它们，我会将其保存为一个单独的问题。