JNR 2023-06-06 · jnr.ffi.byref.ByReference

A ByReference subclass is used when a primitive parameter must be passed by-reference.

For example, the following C code,



extern void get_a(int * ap);

int foo(void) {
    int a;
    // pass a reference to 'a' so get_a() can fill it out
    get_a(&a);

    return a;
}

Would be declared in java as



interface Lib {
    void get_a(@Out IntByReference ap);
}

and used like this



IntByReference ap = new IntByReference();
lib.get_a(ap);
System.out.printf("a from lib=%d\n", a.getValue());

Method Summary

Modifier and Type	Method and Description
public void	fromNative(Runtime The current runtime. runtime, Pointer the native memory buffer. memory, long The offset of the field. offset) Copies the java value from native memory
public T	getValue()
public int	Returns: the size in bytes of the native type nativeSize(Runtime The current runtime. runtime) Gets the size of the native buffer required to store the value
public void	toNative(Runtime The current runtime. runtime, Pointer The native memory buffer. memory, long The offset of the field. offset) Copies the java value to native memory

fromNative	back to summary
public void fromNative(Runtime runtime, Pointer memory, long offset) Copies the java value from native memory Parameters runtime:Runtime The current runtime. memory:Pointer the native memory buffer. offset:long The offset of the field.

fromNative

public void fromNative(Runtime runtime, Pointer memory, long offset)

Copies the java value from native memory

Parameters

getValue	back to summary
public T getValue()

nativeSize	back to summary
public int nativeSize(Runtime runtime) Gets the size of the native buffer required to store the value Parameters runtime:Runtime The current runtime. Returns:int the size in bytes of the native type

nativeSize

public int nativeSize(Runtime runtime)

Gets the size of the native buffer required to store the value

Parameters

Returns:int

the size in bytes of the native type

toNative	back to summary
public void toNative(Runtime runtime, Pointer memory, long offset) Copies the java value to native memory Parameters runtime:Runtime The current runtime. memory:Pointer The native memory buffer. offset:long The offset of the field.

toNative

public void toNative(Runtime runtime, Pointer memory, long offset)

Copies the java value to native memory

Parameters