java.lang.RuntimeException:无法实例化活动ComponentInfo {...}:java.lang.ClassNotFoundException:未找到类

Question

我正在使用Fused Location Provider开发应用程序.当我尝试运行程序时,我收到错误"不幸的是,appname已停止".Eclipse没有显示任何错误,但logcat中存在错误.我不知道如何解决它们.我在这里下载了源代码.请帮我理解我做错了什么？

logcat的

11-05 08:31:41.641: E/AndroidRuntime(795): FATAL EXCEPTION: main
11-05 08:31:41.641: E/AndroidRuntime(795): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.kpbird.fusedlocation/com.kpbird.fusedlocation.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.kpbird.fusedlocation.MainActivity" on path: DexPathList[[zip file "/data/app/com.kpbird.fusedlocation-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.kpbird.fusedlocation-1, /system/lib]]
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.os.Handler.dispatchMessage(Handler.java:99)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.os.Looper.loop(Looper.java:137)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread.main(ActivityThread.java:5103)
11-05 08:31:41.641: E/AndroidRuntime(795):  at java.lang.reflect.Method.invokeNative(Native Method)
11-05 08:31:41.641: E/AndroidRuntime(795):  at java.lang.reflect.Method.invoke(Method.java:525)
11-05 08:31:41.641: E/AndroidRuntime(795):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-05 08:31:41.641: E/AndroidRuntime(795):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-05 08:31:41.641: E/AndroidRuntime(795):  at dalvik.system.NativeStart.main(Native Method)
11-05 08:31:41.641: E/AndroidRuntime(795): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.kpbird.fusedlocation.MainActivity" on path: DexPathList[[zip file "/data/app/com.kpbird.fusedlocation-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.kpbird.fusedlocation-1, /system/lib]]
11-05 08:31:41.641: E/AndroidRuntime(795):  at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)
11-05 08:31:41.641: E/AndroidRuntime(795):  at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
11-05 08:31:41.641: E/AndroidRuntime(795):  at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
11-05 08:31:41.641: E/AndroidRuntime(795):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
11-05 08:31:41.641: E/AndroidRuntime(795):  ... 11 more

Answer 1

因为你的例外是：

ClassNotFoundException: Didn't find class "com.kpbird.fusedlocation.MainActivity"

AndroidManifest.xml添加到您的活动所在的完整包中：

<activity
                android:name="com.kpbird.fusedlocation.MainActivity"

或者确保必须正确定义包名称：

package="com.kpbird.fusedlocation"

我认为您在代码的某个地方输入了错误的应用程序包！

Answer 2

就我而言，问题出在 gradle 上

我将代码从 java 重构为 kotlin，但忘记将其添加到 Gradle 中

apply plugin: 'kotlin-android'