我需要釋放我修改並返回的JNI數組嗎？

Question

我是一個JNI的新手，在我測試的手機之一，我得到關於ReferenceTable overflow的錯誤。我知道這與在本機代碼中不釋放JNI/Java項目有關。

我以爲我不需要釋放任何東西，因爲我使用給定的jfloatarray，替換它的值，然後再次返回原始的JNI對象。我認爲這會讓JNI釋放這個對象本身，因爲它只是取回它。

JNI代碼：

extern "C" 
JNIEXPORT jfloatArray JNICALL Java_methodname(
     JNIEnv *env, jobject thiz, jfloatArray data) 
{ 
float* nativeValues = (float *)env->GetFloatArrayElements(data, 0); 
doSomething(nativeValues);//overwrite the values with new values 
return data; 
} 

JNI錯誤（安卓2.3）：

11-28 15:00:58.069: W/dalvikvm(833): ReferenceTable overflow (max=1024) 
11-28 15:00:58.069: W/dalvikvm(833): Last 10 entries in JNI pinned array reference table: 
11-28 15:00:58.069: W/dalvikvm(833): 1014: 0x405f3750 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1015: 0x405f37b0 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1016: 0x405f3810 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1017: 0x405f3870 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1018: 0x405f38d0 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1019: 0x405f3930 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1020: 0x405f3990 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1021: 0x405f39f0 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1022: 0x405f3a50 cls=[F (20 bytes) 
11-28 15:00:58.069: W/dalvikvm(833): 1023: 0x405f3ab0 cls=[F (20 bytes) 
11-28 15:00:58.074: W/dalvikvm(833): JNI pinned array reference table summary (1024 entries): 
11-28 15:00:58.074: W/dalvikvm(833): 1020 of [F 20B (1020 unique) 
11-28 15:00:58.074: W/dalvikvm(833):  4 of [F 28B (4 unique) 
11-28 15:00:58.074: W/dalvikvm(833): Memory held directly by tracked refs is 20512 bytes 
11-28 15:00:58.074: E/dalvikvm(833): Failed adding to JNI pinned array ref table (1024 entries) 

我該怎麼辦？將數據值複製到新的float*並創建一個新的jfloatarray？

Answer 1

當您通過GetFloatArrayElements(..)函數獲取元素時，您需要釋放數組元素，因爲JVM會將其標記爲「在本機代碼中使用」。 請致電ReleaseFloatArrayElements()。 查看細節： http://docs.oracle.com/javase/6/docs/technotes/guides/jni/spec/functions.html#wp17440