Mapping Native Types to JNIWrapper Classes
Please find below the mappings table for most commonly used data types along with some comments.
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JNIWrapper Type
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Comments
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Boolean Types
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bool
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Character Types
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char
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wchar_t
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uchar *
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Integer Types
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short
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The unsigned types are represented by prepending U to the type name, e.g. unsigned
int (or unsigned) type is UInt.
There are also types for predefined-width integers: Int8, Int16, Int32 and Int64, they also have the
unsigned variants.
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int
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long
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Floating-point Types
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float
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double
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long double
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Long double is the same as double (8-byte floating-point value) on win32 platform.
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Pointer Types (not arrays)
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void *
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const
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Use Pointer.Const if the referenced object is not to be modified by the calling function.
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type *
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To create a pointer to the value (variable) of a known type, use the Pointer class.
For
example: int *i; is Pointer i = new Pointer(new Int());
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type *
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Use Pointer.OutOnly if the referenced value is not read by the calling function.
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char *
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wchar_t *
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Arrays
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<c primitive type>[n]
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For example:
int i[10];
is
PrimitiveArray i =
new PrimitiveArray(Int.class, 10);
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Structures and Unions
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struct
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union
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Function Pointers
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To create an object callable from the native code use the
Callback class.
To call a function returned from the native code use the method
asFunction
of the Pointer.Void class.
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Windows
API includes many data types that are not listed here (for example, DWORD,
HANDLE). If you need to use one of such types, read Windows-specific
documentation such as MSDN to find out the actual C type that
corresponds to it (for example, LPSTR corresponds to char*) and use the
relevant JNIWrapper type for the argument. You can also check the
Windows Data Types table that we have created for your
reference.
