来自JNI的警报Dialog Builder调用中的空指针异常

时间：2016-08-16 17:26:29

标签： java android c++ java-native-interface

我知道有很多问题已经被问过，我已经看过这篇文章已经处理过这类错误，但我正在参加JNI电话的特别竞赛。 Android JNI - Call AttachCurrentThread without DetachCurrentThread

所以这就是我的所作所为： 我有一个单独的c ++线程运行一些代码，并在某些时候（在计时器结束后）我需要在java中调用一个回调函数。此回调函数用于显示一些警报，然后运行一些代码。

所以基本上这是我的代码c ++方面：

JNIEXPORT void JNICALL package_endTrialJava(){

    LOGD("EndTrialJava");
    JNIEnv* env;

    int getEnvStat = g_jvm->GetEnv((void **)&env, JNI_VERSION_1_6);
    if (getEnvStat == JNI_EDETACHED) {
        LOGD("GetEnv: not attached");
        //if (g_jvm->AttachCurrentThread((void **) &env, NULL) != 0) {
        if (g_jvm->AttachCurrentThread(&env, NULL) != 0) {
            LOGD("Failed to attach");
        }
        else{
            jobject javaObjectRef = env->NewObject(javaClassRef, javaMethodRef);
            env->CallVoidMethod(javaObjectRef, javaMethodRef);
        }
    } else if (getEnvStat == JNI_OK) {
        //
    } else if (getEnvStat == JNI_EVERSION) {
        LOGD("GetEnv: version not supported");
    }

    //See https://stackoverflow.com/questions/26534304/android-jni-call-attachcurrentthread-without-detachcurrentthread
    g_jvm->DetachCurrentThread();
}

然后在Java端调用的函数执行以下操作：         AlertDialog.Builder alert = new AlertDialog.Builder（MainActivity.this）;         alert.setTitle（“下一步技术”）;         alert.setMessage（“你现在将尝试其他技术”）; 

    alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
        alertBeforeTrial();
        return ;

      }
    });
    AlertDialog alertdialog = alert.create();
    alertdialog.show();

但是我收到以下错误：

W/art     (24708): Thread[20,tid=24780,Native,Thread*=0x4e1ab1c8,peer=0x649247a0,"Thread-1128"] attached without supplying a name
D/TEST    (24708): End Trial
F/art     (24708): art/runtime/check_jni.cc:64] JNI DETECTED ERROR IN APPLICATION: JNI CallVoidMethodV called with pending exception 'java.lang.NullPointerException' thrown in unknown throw location
F/art     (24708): art/runtime/check_jni.cc:64]     in call to CallVoidMethodV
F/art     (24708): art/runtime/check_jni.cc:64] "Thread-1128" prio=5 tid=20 Runnable
F/art     (24708): art/runtime/check_jni.cc:64]   | group="main" sCount=0 dsCount=0 obj=0x649247a0 self=0x4e1ab1c8
F/art     (24708): art/runtime/check_jni.cc:64]   | sysTid=24780 nice=0 cgrp=apps sched=0/0 handle=0x493da480
F/art     (24708): art/runtime/check_jni.cc:64]   | state=R schedstat=( 282584 1729083 7 ) utm=0 stm=0 core=3 HZ=100
F/art     (24708): art/runtime/check_jni.cc:64]   | stack=0x4e9cf000-0x4e9d3000 stackSize=1016KB
F/art     (24708): art/runtime/check_jni.cc:64]   (no managed stack frames)
F/art     (24708): art/runtime/check_jni.cc:64] 
F/art     (24708): art/runtime/runtime.cc:203] Runtime aborting...
F/art     (24708): art/runtime/runtime.cc:203] Aborting thread:
F/art     (24708): art/runtime/runtime.cc:203] "Thread-1128" prio=5 tid=20 Runnable
F/art     (24708): art/runtime/runtime.cc:203]   | group="main" sCount=0 dsCount=0 obj=0x649247a0 self=0x4e1ab1c8
F/art     (24708): art/runtime/runtime.cc:203]   | sysTid=24780 nice=0 cgrp=apps sched=0/0 handle=0x493da480
F/art     (24708): art/runtime/runtime.cc:203]   | state=R schedstat=( 1254668 1729083 7 ) utm=0 stm=0 core=3 HZ=100
F/art     (24708): art/runtime/runtime.cc:203]   | stack=0x4e9cf000-0x4e9d3000 stackSize=1016KB
F/art     (24708): art/runtime/runtime.cc:203]   native: art::Thread::DumpStack(std::ostream&) const+87 [0x41709b78] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: ??? [0x41701c62] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: art::Runtime::Abort()+79 [0x41702204] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: art::LogMessage::~LogMessage()+507 [0x415ad89c] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: ??? [0x415b5ad4] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: art::JniAbortF(char const*, char const*, ...)+51 [0x415b6254] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: ??? [0x415b817c] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: ??? [0x415b83e6] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: ??? [0x415befe6] (libart.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: _JNIEnv::CallVoidMethod(_jobject*, _jmethodID*, ...)+40 [0x48c8ac68] (libnative.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: package_endTrialJava+268 [0x48c8f8f0] (libnative.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: FluidMechanics::Impl::endTrial()+772 [0x48c8fc20] (libnative.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: std::thread::_Impl<std::_Bind_simple<std::_Mem_fn<void (FluidMechanics::Impl::*)()> (FluidMechanics::Impl*)> >::_M_run()+36 [0x48c8a128] (libnative.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: execute_native_thread_routine+11 [0x47f2c53c] (libgnustl_shared.so)
F/art     (24708): art/runtime/runtime.cc:203]   (no managed stack frames)
F/art     (24708): art/runtime/runtime.cc:203] Pending exception java.lang.NullPointerException thrown by 'unknown throw location'
F/art     (24708): art/runtime/runtime.cc:203] java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
F/art     (24708): art/runtime/runtime.cc:203]   at android.content.pm.ApplicationInfo android.content.ContextWrapper.getApplicationInfo() (ContextWrapper.java:152)
F/art     (24708): art/runtime/runtime.cc:203]   at android.content.res.Resources$Theme android.view.ContextThemeWrapper.getTheme() (ContextThemeWrapper.java:103)
F/art     (24708): art/runtime/runtime.cc:203]   at int android.app.AlertDialog.resolveDialogTheme(android.content.Context, int) (AlertDialog.java:143)
F/art     (24708): art/runtime/runtime.cc:203]   at void android.app.AlertDialog$Builder.<init>(android.content.Context) (AlertDialog.java:360)
F/art     (24708): art/runtime/runtime.cc:203]   at void fr.limsi.ARViewer.MainActivity.alertBeforeNewTechnique() (MainActivity.java:329)
F/art     (24708): art/runtime/runtime.cc:203]   at void fr.limsi.ARViewer.MainActivity.showAlerts() (MainActivity.java:320)
F/art     (24708): art/runtime/runtime.cc:203]   at void fr.limsi.ARViewer.MainActivity.endTrial() (MainActivity.java:369)
F/art     (24708): art/runtime/runtime.cc:203] Dumping all threads without appropriate locks held: thread list lock mutator lock
F/art     (24708): art/runtime/runtime.cc:203] All threads:
F/art     (24708): art/runtime/runtime.cc:203] DALVIK THREADS (20):
F/art     (24708): art/runtime/runtime.cc:203] "main" prio=5 tid=1 Native
F/art     (24708): art/runtime/runtime.cc:203]   | group="main" sCount=0 dsCount=0 obj=0x646c7b70 self=0x41da3c80
F/art     (24708): art/runtime/runtime.cc:203]   | sysTid=24708 nice=0 cgrp=apps sched=0/0 handle=0x4010b154
F/art     (24708): art/runtime/runtime.cc:203]   | state=S schedstat=( 2797045067 1500623419 9968 ) utm=213 stm=66 core=0 HZ=100
F/art     (24708): art/runtime/runtime.cc:203]   | stack=0xbe552000-0xbe556000 stackSize=8MB
F/art     (24708): art/runtime/runtime.cc:203]   native: android::Looper::pollOnce(int, int*, int*, void**)+92 [0x401ab94d] (libutils.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: android::NativeMessageQueue::pollOnce(_JNIEnv*, int)+22 [0x40254331] (libandroid_runtime.so)
F/art     (24708): art/runtime/runtime.cc:203]   native: oatexec+18045636 [0x634efac4] (system@framework@boot.oat)
F/art     (24708): art/runtime/runtime.cc:203]   at android.os.MessageQueue.nativePollOnce(Native method)
F/art     (24708): art/runtime/runtime.cc:203]   at android.os.MessageQueue.next(MessageQueue.java:138)
F/art     (24708): art/runtime/runtime.cc:203]   at android.os.Looper.loop(Looper.java:123)
F/art     (24708): art/runtime/runtime.cc:203]   at android.app.ActivityThread.main(ActivityThread.java:5030)
F/art     (24708): art/runtime/runtime.cc:203]   at java.lang.reflect.Method.invoke(Native method)
F/art     (24708): art/runtime/runtime.cc:203]   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
F/art     (24708): art/runtime/runtime.cc:203]   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)

我的一个有根据的猜测是，这与UIThread有关。我想从我在c ++中的线程到java函数的调用不在UIThread上，这就是我得到错误的原因。但我不确定它实际上是问题，我不知道如何解决这个问题。你们中的任何人都知道我能做些什么。

编辑：所以我尝试删除所有处理AlertDialog的代码，但问题没有发生。所以它似乎是UIThread的一个问题或者是AlertDialog的一个问题......但是我猜它更像是一个UIThread问题，因为在这个函数之外创建一个简单的AlertDialog就可以了。

1 个答案:

答案 0 :(得分：2)

您的NewObject电话存在问题。

传递给NewObject的第二个参数应该是对构造函数的引用，但在您的情况下，它与您使用CallVoidMethod调用的方法相同。

  

构造一个新的Java对象。方法ID指示要调用的构造方法。必须通过使用＆lt; init＆gt;调用GetMethodID（）来获取此ID。作为方法名称和void（V）作为返回类型。

您尚未显示初始化javaMethodRef的代码，因此不清楚它是构造函数还是其他方法。如果它是构造函数，您只需要调用一次，CallVoidMethod调用是多余的。如果它不是构造函数，则应该调用构造函数。您可以使用与此类似的代码获取引用：

jmethodID constructor = env->GetMethodID(javaClassRef, "<init>", "()V");
jobject javaObjectRef = env->NewObject(javaClassRef, constructor);

如果您的构造函数接受参数，请将其类型添加到签名中，并在NewObject之后将其传递给constructor。

相关问题
最新问题