Question

我正在Kotlin进行一个Android Studio项目，我想通过MediaPlayer和SoundPool包含一些音乐和声音FX。但是，我遇到了SoundPool不能解决的问题。我将不胜感激。

当我尝试将声音加载到SoundPool时出现问题。我遵循了Android文档和一些示例。

这是我的代码：

var mediaPlayer : MediaPlayer? = null
@Suppress("DEPRECATION")
val soundPool : SoundPool = SoundPool(5,AudioManager.STREAM_MUSIC,0)
val soundIdAlarm = soundPool.load(ctx, com.example.project.R.raw.alarm, 0)

该错误是由.load（...）行引起的。我什至可以使用MediaPlayer播放声音，如以下行所示：

mediaPlayer = MediaPlayer.create(ctx,com.example.project.R.raw.alarm)
mediaPlayer?.start()

控制台输出为：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.project, PID: 12595
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.project/com.example.project.view.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2843)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at android.content.ContextWrapper.getResources(ContextWrapper.java:91)
        at android.view.ContextThemeWrapper.getResourcesInternal(ContextThemeWrapper.java:127)
        at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:121)
        at android.support.v7.app.AppCompatActivity.getResources(AppCompatActivity.java:543)
        at android.media.SoundPool.load(SoundPool.java:224)
        at com.example.project.sound.SoundManager.<init>(SoundManager.kt:16)
        at com.example.project.presenter.MainActivityPresenter.<init>(MainActivityPresenter.kt:10)
        at com.example.project.view.MainActivity.<init>(MainActivity.kt:13)
        at java.lang.Class.newInstance(Native Method)
        at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:69)
        at android.support.v4.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:43)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1215)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2831)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

这些行：

    at android.media.SoundPool.load(SoundPool.java:224)
    at com.example.project.sound.SoundManager.<init>(SoundManager.kt:16)
    at com.example.project.presenter.MainActivityPresenter.<init>(MainActivityPresenter.kt:10)
    at com.example.project.view.MainActivity.<init>(MainActivity.kt:13)
    at java.lang.Class.newInstance(Native Method)
    at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:69)
    at android.support.v4.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:43)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1215)

建议您正在初始化Activity的构造函数中的代码。最早应在Activity的{{1}}方法中进行。请参阅Understand the Activity Lifecycle上的developers.google.com文章，以更好地理解主题。

如何使用SoundPool修复“无法实例化活动ComponentInfo”错误

1 个答案: