CallStaticVoidMethodがJNIで無効なjobjectの使用をスローされた理由

Question

NativeメソッドでMainActivityのネイティブメソッドを呼び出そうとすると、初心者のためにJNIにいます。ネイティブmethod.ThenによってCallStaticVoidMethodコールMainActivityのstaticメソッドプログラムがクラッシュ：

これはネイティブメソッドのコードです：

void Java_com_lijing_ndkjnidemeo_activity_MainActivity_staticMethod(JNIEnv *env, jobject obj, jobject aty) { 
     LOGI("native_staticMethod"); 
     jclass cls; 
     jmethodID mid; 
     //1.Get the class method id 
     cls = (*env)->GetObjectClass(env, aty); 
     mid = (*env)->GetStaticMethodID(env, cls, "changeStr", "()V"); 
     if (mid == NULL) { 
      LOGE("GetStaticMethodID error"); 
      return; /* method not found */ 
     } 
     LOGE("GetStaticMethodID sucess"); 
     //2.Call the CallStatic<ReturnValueType>Method function to call the corresponding function. 
     (*env)->CallStaticVoidMethod(env, cls, mid); 
    } 

ネイティブ方法はMainActivityに呼び出します。

private void jniTextMethod8() { 
     staticMethod(this); 
     tvStaticMethod.setText(sStr); 
    } 

public static native String staticMethod(MainActivity aty); 

public static void changeStr() { 
     sStr = "Change String"; 
    } 

ログイン：

11-07 09:57:35.477 4310-4310/com.lijing.ndkjnidemeo I/JNI_UTIL: native_staticMethod 
11-07 09:57:35.477 4310-4310/com.lijing.ndkjnidemeo E/JNI_UTIL: GetStaticMethodID sucess 
11-07 09:57:35.493 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] JNI DETECTED ERROR IN APPLICATION: use of invalid jobject 0xffde5e68 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410]  from java.lang.String com.lijing.ndkjnidemeo.activity.MainActivity.staticMethod(com.lijing.ndkjnidemeo.activity.MainActivity) 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] "main" prio=5 tid=1 Runnable 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] | group="main" sCount=0 dsCount=0 obj=0x73712258 self=0xf3df4a00 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] | sysTid=4310 nice=0 cgrp=default sched=0/0 handle=0xf777cc00 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] | state=R schedstat=(304952424 35818763 258) utm=12 stm=17 core=1 HZ=100 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] | stack=0xff5e8000-0xff5ea000 stackSize=8MB 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] | held mutexes= "mutator lock"(shared held) 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] native: #00 pc 0058b0e2 /system/lib/libart.so (art::DumpNativeStack(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, int, char const*, art::ArtMethod*, void*)+226) 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] native: #01 pc 00550d2e /system/lib/libart.so (art::Thread::Dump(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) const+286) 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] native: #02 pc 003a489f /system/lib/libart.so (art::JavaVMExt::JniAbort(char const*, char const*)+1247) 
11-07 09:57:35.494 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] native: #03 pc 003a5fc2 /system/lib/libart.so (art::JavaVMExt::JniAbortF(char const*, char const*, ...)+116) 
11-07 09:57:35.495 4310-4310/com.lijing.ndkjnidemeo A/art: art/runtime/java_vm_ext.cc:410] native: #04 pc 00548fc7 /system/lib/libart.so (art::Thread::DecodeJObject(_jobject*) const+1975) 

Answer 1

ネイティブ関数から何も返されません。

void 
Java_com_lijing_ndkjnidemeo_activity_MainActivity_staticMethod(
    JNIEnv *env, 
    jobject obj, 
    jobject aty) 

として

public static native String staticMethod(MainActivity aty); 

しかし、Cであなたはどちらか

public static native void staticMethod(MainActivity aty); 

たり、CににしてJavaを変更する必要があります。

ネイティブ関数は次のようにJavaで定義されています次のようなもの：

jobject 
Java_com_lijing_ndkjnidemeo_activity_MainActivity_staticMethod(
    JNIEnv *env, 
    jobject obj, 
    jobject aty) { 
    .. 
    return something; 
}