jnr.ffi.byref

Interface ByReference<T>

All Known Implementing Classes:

AbstractNumberReference, AbstractReference, AddressByReference, ByteByReference, DoubleByReference, FloatByReference, IntByReference, LongLongByReference, NativeLongByReference, NumberByReference, PointerByReference, ShortByReference

public interface ByReference<T>

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
void	fromNative(Runtime runtime, Pointer memory, long offset) Copies the java value from native memory
T	getValue()
int	nativeSize(Runtime runtime) Gets the size of the native buffer required to store the value
void	toNative(Runtime runtime, Pointer memory, long offset) Copies the java value to native memory

Method Detail

nativeSize

int nativeSize(Runtime runtime)

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

Parameters:

runtime - The current runtime.

Returns:

the size in bytes of the native type

toNative

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

Copies the java value to native memory

Parameters:

runtime - The current runtime.

memory - The native memory buffer.

offset - The offset of the field.

fromNative

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

Copies the java value from native memory

Parameters:

runtime - The current runtime.

memory - the native memory buffer.

offset - The offset of the field.

getValue

T getValue()