jclass

jclass is a JNI type used in native code (C or C++) to represent a reference to a Java class. In JNI, a class reference refers to an instance of the Java class object (the runtime java.lang.Class object) and is used when native code needs to interact with Java classes, such as accessing static methods or fields or obtaining method identifiers.

A jclass value is typically obtained by calling FindClass from native code, or it can be received as a parameter to a native method that exposes a Java class to native code. Once obtained, the reference may be used to query and invoke static members via functions such as GetStaticMethodID, GetStaticFieldID, and to call static methods with CallStatic... variants. It can also be passed to methods that require a class reference, including calls that need a class argument through the jvalue union.

Lifecycle and reference management are important aspects of working with jclass. References returned by JNI functions are usually local to the native method and are automatically freed when the native method returns. If a class reference must be kept longer than the duration of a native method, it should be converted to a global reference using NewGlobalRef and later released with DeleteGlobalRef. Local references can be freed earlier with DeleteLocalRef if desired.

Notes and considerations include that a jclass indeed represents a reference to a Java class object, typically java.lang.Class, but it is used in native code as a distinct JNI type. In multi-threaded contexts, class references may depend on the appropriate class loader, and in some cases FindClass must be performed in the correct loader context to succeed. The jvalue union used for method calls also includes a jclass component, enabling its use as an argument in certain JNI invocation variants.