JNI Jobject examples

jobject_examples.h

using namespace std;

//----------------------Convert a Java data------------------------\\


jstring create_jstring(JNIEnv *env, const char *data) {
    return env->NewStringUTF(data);
}

jint create_jint(JNIEnv *env, int data){
    return data;
}

jfloat create_jfloat(JNIEnv *env, float data){
    return data;
}

jdouble create_jdouble(JNIEnv *env, double data){
    return data;
}

jboolean create_jboolean(JNIEnv *env, bool data){
    return data;
}

jchar create_jchar(JNIEnv *env, char data){
    return data;
}

jshort create_jshort(JNIEnv *env, short data){
    return data;
}

string create_string(JNIEnv *env, jstring data){
    return env->GetStringUTFChars(data,0);
}

int create_int(JNIEnv *env, jint data){
    return data;
}

float create_float(JNIEnv *env, jfloat data){
    return data;
}

double create_double(JNIEnv *env, jdouble data){
    return data;
}

bool create_boolean(JNIEnv *env, jboolean data){
    return data;
}

char create_char(JNIEnv *env, jchar data){
    return data;
}

short create_short(JNIEnv *env, jshort data){
    return data;
}


//------------------------------------------------------------------\\

//-----------------------------Call a Java method-----------------------------\\

//Log.v
void call_Log_v(JNIEnv *env,jstring title,jstring content){
    jclass log_class = env->FindClass("android/util/Log");
    jmethodID print = env->GetStaticMethodID(log_class,"v","(Ljava/lang/String;Ljava/lang/String;)I");
    env->CallStaticIntMethod(log_class,print,title,content);
}

//System.exit
void call_exit(JNIEnv *env,int exit_code){
    jclass system_class = env->FindClass("java/lang/System");
    jmethodID exit = env->GetStaticMethodID(system_class,"exit", "(I)V");
    env->CallStaticVoidMethod(system_class,exit,exit_code);
}

//getApplicationContext
jobject call_getApplicationContext(JNIEnv *env, jobject thiz){
    jclass application_context_class = env->FindClass("android/content/Context");
    jmethodID getApplicationContext = env->GetMethodID(application_context_class,"getApplicationContext","()Landroid/content/Context;");
    return env->CallObjectMethod(thiz,getApplicationContext);
}

//Toast
void call_toast_show(JNIEnv *env, jobject context,jstring content){
    jclass toast_class = env->FindClass("android/widget/Toast");
    jmethodID makeText = env->GetStaticMethodID(toast_class,"makeText","(Landroid/content/Context;Ljava/lang/CharSequence;I)Landroid/widget/Toast;");
    jobject toast_init = env->CallStaticObjectMethod(toast_class,makeText,context,content,1);
    jmethodID show = env->GetMethodID(toast_class,"show", "()V");
    env->CallVoidMethod(toast_init,show);
}

//findViewById
jobject call_findViewById(JNIEnv *env,jobject thiz,int view_id){
    jclass findviewbyid_class = env->FindClass("androidx/appcompat/app/AppCompatActivity");
    jmethodID findViewById = env->GetMethodID(findviewbyid_class,"findViewById", "(I)Landroid/view/View;");

    return env->CallObjectMethod(thiz,findViewById,view_id);
}

//setText
void call_setText(JNIEnv *env, jobject view, jstring text){
    jclass setText_class = env->FindClass("android/widget/TextView");
    jmethodID integer_setText_method = env->GetMethodID(setText_class,"setText","(Ljava/lang/CharSequence;)V");
    env->CallVoidMethod(view, integer_setText_method, text);
}

//getApplicationInfo
jobject call_getApplicationInfo(JNIEnv *env, jobject thiz){
    jclass class_ = env->FindClass("android/content/Context");
    jmethodID method = env->GetMethodID(class_,"getApplicationInfo","()Landroid/content/pm/ApplicationInfo;");
    return env->CallObjectMethod(thiz, method);
}

//getString
jstring call_getString(JNIEnv *env,jobject thiz ,int string_id){
    jclass class_ = env->FindClass("android/content/Context");
    jmethodID method = env->GetMethodID(class_,"getString","(I)Ljava/lang/String;");
    return (jstring)env->CallObjectMethod(thiz, method,string_id);
}

//String.valueOf(float)
jstring call_String_valueOf_long(JNIEnv *env, long data){
    jclass class_ = env->FindClass("java/lang/String");
    jmethodID method = env->GetStaticMethodID(class_,"valueOf", "(J)Ljava/lang/String;");
    return (jstring)env->CallStaticObjectMethod(class_,method,(jlong)data);
}

//String.valueOf(boolean)
jstring call_String_valueOf_boolean(JNIEnv *env, bool data){
    jclass class_ = env->FindClass("java/lang/String");
    jmethodID method = env->GetStaticMethodID(class_,"valueOf", "(Z)Ljava/lang/String;");
    return (jstring)env->CallStaticObjectMethod(class_,method,(jboolean)data);
}

//String.valueOf(char)
jstring call_String_valueOf_char(JNIEnv *env, char data){
    jclass class_ = env->FindClass("java/lang/String");
    jmethodID method = env->GetStaticMethodID(class_,"valueOf", "(C)Ljava/lang/String;");
    return (jstring)env->CallStaticObjectMethod(class_,method,(jchar)data);
}

//String.valueOf(double)
jstring call_String_valueOf_double(JNIEnv *env, double data){
    jclass class_ = env->FindClass("java/lang/String");
    jmethodID method = env->GetStaticMethodID(class_,"valueOf", "(D)Ljava/lang/String;");
    return (jstring)env->CallStaticObjectMethod(class_,method,(jdouble)data);
}

//String.valueOf(jobject)
jstring call_String_valueOf_jobject(JNIEnv *env, jobject data){
    jclass class_ = env->FindClass("java/lang/String");
    jmethodID method = env->GetStaticMethodID(class_,"valueOf", "(Ljava/lang/Object;)Ljava/lang/String;");
    return (jstring)env->CallStaticObjectMethod(class_,method,data);
}

//------------------------------------------------------------------\\

//------------------Get a Java Field------------------\\

string get_jstring_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID string_ = env->GetFieldID(class_,field_name, "Ljava/lang/String;");
    jstring data = (jstring)env->GetObjectField(get_from_class,string_);
    return env->GetStringUTFChars(data,0);
}

int get_jint_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID int_ = env->GetFieldID(class_,field_name, "I");
    return env->GetIntField(get_from_class,int_);
}

float get_jfloat_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID float_ = env->GetFieldID(class_,field_name, "F");
    return env->GetFloatField(get_from_class,float_);
}

double get_jdouble_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID double_ = env->GetFieldID(class_,field_name, "D");
    return env->GetDoubleField(get_from_class,double_);
}

bool get_jboolean_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID boolean_ = env->GetFieldID(class_,field_name, "Z");
    return env->GetBooleanField(get_from_class,boolean_);
}

char get_jchar_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID char_ = env->GetFieldID(class_,field_name, "C");
    return env->GetCharField(get_from_class,char_);
}

short get_jshort_field(JNIEnv *env, jobject get_from_class, const char *field_name){
    jclass class_ = env->GetObjectClass(get_from_class);
    jfieldID short_ = env->GetFieldID(class_,field_name, "S");
    return env->GetShortField(get_from_class,short_);
}

//------------------------------------------------------------------\\

how to pass jobject from one vm to anther, any solutions:

https://stackoverflow.com/questions/79280483/jni-issue-passing-java-runnable-object-to-jni-in-custom-gluon-attach-plugin