JNI WARNING: CallObjectMethod expected return type 'L'

初学C调用java代码，出错如下：
07-14 10:36:15.028 27654-27654/study.jnidemo W/dalvikvm:            JNI WARNING: CallObjectMethod expected return type 'L'
07-14 10:36:15.028 27654-27654/study.jnidemo W/dalvikvm:              calling Lstudy/jnidemo/JniDemoActivity;.importCert ()V
07-14 10:36:15.028 27654-27654/study.jnidemo W/dalvikvm:              in Lstudy/jnidemo/JniDemoActivity;.jniImportCert:()V (CallObjectMethod)

仔细检查C代码发现问题：
void
Java_study_jnidemo_JniDemoActivity_jniImport (JNIEnv
*
env,
jobject
thiz
){
          
jclass
cls
=(*env)->
GetObjectClass(env
,thiz);
          
if(cls
!=NULL){
                   
jstring
str
;
                   
jmethodID
method3=(*env
)->GetMethodID(
env,cls
,"import",
"()V");
                   
if(method3
!=NULL){
                             (*
env)->CallObjectMethod
(env,
thiz,method3
);
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[align=left]把[/align]
                             (*
env)->CallObjectMethod
(env,
thiz,method3
);
改成
 
                             (*
env)->CallVoidMethod
(env,
thiz,method3
);