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com.dautelle.util
Class Union

java.lang.Object
  com.dautelle.util.Struct
      com.dautelle.util.Union

public abstract class Union

extends Struct

This class represents a C/C++ union; it works in the same way as Struct (sub-class) except that all members are mapped to the same location in memory.

Here is an example of C union:

     union Number {
         int   asInt;
         float asFloat;
         char  asString[12];
     };

And its Java equivalent:

     public class Number extends Union {
         Signed32   asInt    = new Signed32();
         Float32    asFloat  = new Float32();
         UTF8String asString = new UTF8String(12);
     }

As for any Struct, fields are directly accessible:

     Number num = new Number();
     num.asInt.set(23);
     num.asString.set("23"); // Null terminated (C compatible)
     float f = num.asFloat.get();

This class is public domain (not copyrighted).

Version:

5.2, September 28, 2003

Author:

Jean-Marie Dautelle

Nested Class Summary

Nested classes inherited from class com.dautelle.util.Struct

Struct.ArrayMember, Struct.Bool, Struct.Enum16, Struct.Enum32, Struct.Enum64, Struct.Enum8, Struct.Float32, Struct.Float64, Struct.Member, Struct.Reference32, Struct.Reference64, Struct.Signed16, Struct.Signed32, Struct.Signed64, Struct.Signed8, Struct.StructMember, Struct.Unsigned16, Struct.Unsigned32, Struct.Unsigned8, Struct.UTF8String

Constructor Summary

Union()
Default constructor.

Union(java.nio.ByteBuffer buffer)
Creates a Union backed by the specified ByteBuffer.

Methods inherited from class com.dautelle.util.Struct

address, byteBuffer, byteOrder, copy, equals, hashCode, isPacked, size, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Union

public Union()

Default constructor. Top-level Union created using this constructor are backed by a direct buffer.

Union

public Union(java.nio.ByteBuffer buffer)

Creates a Union backed by the specified ByteBuffer.

Parameters:

buffer - the byte buffer for this Union.