Re: how to convert c struct to java classes

On 23-12-2009 05:03, warrior wrote:


Multiple ways.

DataInputStream wrapped around a ByteArrayInputStream wrapped
around the byte array.

NIO ByteBuffer wrapped around the byte array.

More custom solution. Example:

import dk.vajhoej.record.Alignment;
import dk.vajhoej.record.Endian;
import dk.vajhoej.record.FieldType;
import dk.vajhoej.record.Struct;
import dk.vajhoej.record.StructField;

/*
  * struct data
  * {
  * long int liv;
  * int bv1 : 4;
  * int bv2 : 4;
  * short int siv;
  * };
  *
  * With a compiler and settings that uses little endian, natural
  * alignment, sizeof(long)=4, sizeof(short)=2 etc..
  */
@Struct(endianess=Endian.LITTLE, alignment=Alignment.NATURAL)
public class Data {
     @StructField(n=0,type=FieldType.INT4)
     private int liv;
     @StructField(n=1,type=FieldType.BIT,length=4)
     private int bv1;
     @StructField(n=2,type=FieldType.BIT,length=4)
     private int bv2;
     @StructField(n=3,type=FieldType.INT2)
     private int siv;
     public int getLiv() {
         return liv;
     }
     public int getBv1() {
         return bv1;
     }
     public int getBv2() {
         return bv2;
     }
     public int getSiv() {
         return siv;
     }
}

import dk.vajhoej.record.RecordException;
import dk.vajhoej.record.StructReader;

public class CStruct {
     public static void main(String[] args) throws RecordException {
         byte[] b = { 7, 0, 0, 0, 0x12, 0, 3, 0 };
         StructReader sr = new StructReader(b);
         Data o = sr.read(Data.class);
         System.out.println(o.getLiv() + " " + o.getBv1() + " " +
o.getBv2() + " " + o.getSiv());
     }
}


The Java way is to have sub classes that overrides a certain
method with the implementation you need.

Arne