(标签-android|关键词-Class)

Question

问题：android studio 创建mqtt客户端项目，虚拟机运行报错，闪退，单击app显示keeps stopping
logcat无报错，
android版本，4.2.1，sdk 30
运行里有错误，但是不知道如何进行修改，请各位帮忙

01/03 10:17:42: Launching 'app' on Red mi Note10.
Install successfully finished in 292 ms.
$ adb shell am start -n "com.example.mqttest/com.example.mqttest.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 7345 on device 'Red_mi_Note10 [emulator-5554]'.
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
I/studio.deploy: Finished instrumenting
D/NetworkSecurityConfig: No Network Security Config specified, using platform default
D/NetworkSecurityConfig: No Network Security Config specified, using platform default
D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
W/System: A resource failed to call close. 
W/example.mqttes: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
W/example.mqttes: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
   _ Process: com.example.mqttest, PID: 7345
    java.lang.NoClassDefFoundError: Failed resolution of: Landroid/support/v4/content/LocalBroadcastManager;
        at org.eclipse.paho.android.service.MqttAndroidClient.registerReceiver(MqttAndroidClient.java:450)
        at org.eclipse.paho.android.service.MqttAndroidClient.connect(MqttAndroidClient.java:428)
        at com.example.mqttest.MainActivity.onCreate(MainActivity.java:61)
        at android.app.Activity.performCreate(Activity.java:7994)
        at android.app.Activity.performCreate(Activity.java:7978)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.v4.content.LocalBroadcastManager" on path: DexPathList[[zip file "/data/app/~~45WqZ2v-kXjjtIc1TEEbHw==/com.example.mqttest-SIO2DBjmk_uvBqu6c1pNeQ==/base.apk"],nativeLibraryDirectories=[/data/app/~~45WqZ2v-kXjjtIc1TEEbHw==/com.example.mqttest-SIO2DBjmk_uvBqu6c1pNeQ==/lib/x86, /system/lib, /system_ext/lib]]
        at _dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:207)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)_
        at org.eclipse.paho.android.service.MqttAndroidClient.registerReceiver(MqttAndroidClient.java:450) 
        at org.eclipse.paho.android.service.MqttAndroidClient.connect(MqttAndroidClient.java:428) 
        at com.example.mqttest.MainActivity.onCreate(MainActivity.java:61) 
        at android.app.Activity.performCreate(Activity.java:7994) 
        at android.app.Activity.performCreate(Activity.java:7978) 
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) ___
I/Process: Sending signal. PID: 7345 SIG: 9



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Answer 1

根据你提供的 logcat 信息，我发现你的程序出现了 java.lang.NoClassDefFoundError 和 java.lang.ClassNotFoundException 的异常，这意味着你的程序在运行时找不到某个类的定义。具体来说，你的程序找不到 android.support.v4.content.LocalBroadcastManager 这个类，这个类是用于在应用内部发送和接收广播的一个工具类。