Java version of the example

The same binary files can be written and read with the Java version of the Bindrv library. The code producing the binary file burgdatabin looks as follows with Java—some of the calls to methods bdrv.put* have been combined for improved readability of our Java code (this does not impact the generated output).

/**** Input data ****/
 static final double[] vdata={15,100,90,60,40,15,10, 1};   // VALUE
 static final double[] wdata={ 2, 20,20,30,40,30,60,10};   // WEIGHT
 static final String[] ind={"camera", "necklace", "vase", "picture", "tv",
                   "video", "chest", "brick" };            // Index names
 static final int datasize=8;

/**** Create a BinDrv data file ****/
 static void writeBurgBin() throws IOException
 {
  BinDrvWriter bdrv;
  FileOutputStream f;

  f=new FileOutputStream("burgdatabin");
  bdrv=new BinDrvWriter(f);

  bdrv.putControl(bdrv.CTRL_LABEL).put("BurgData");      // label:
  bdrv.putControl(bdrv.CTRL_OPENLST);                    // [
  for(int i=0;i<datasize;i++)
  {                                                      //  (index)
   bdrv.putControl(bdrv.CTRL_OPENNDX).put(ind[i]).putControl(bdrv.CTRL_CLOSENDX);
   bdrv.putControl(bdrv.CTRL_OPENLST).put(vdata[i]).put(wdata[i]);
   bdrv.putControl(bdrv.CTRL_CLOSELST);                  //   [val1 val2]
  }
  bdrv.putControl(bdrv.CTRL_CLOSELST);                   // ]
  f.close();
 }

The Java code for reading the binary results file resdatabin has the same structure as the C version that we have seen in the previous section. Again, we have implemented only a limited number of tests whether the data read corresponds to the expected format.

 static void readBurgBin() throws IOException
 {
  BinDrvReader bdrv;
  FileInputStream f;
  int c;

  f=new FileInputStream("resdatabin");
  bdrv=new BinDrvReader(f);

  if(bdrv.getControl()==BinDrvReader.CTRL_LABEL)
  {
   while(bdrv.nextToken()>=0)
   {
    String s=bdrv.getString();                            // label:
    if(s.equals("SolTake"))
    {
     System.out.println("Solution values:");
     bdrv.getControl();
     while(bdrv.nextToken()>=0)
     {
      c=bdrv.getControl();                                // [
      if(c==BinDrvReader.CTRL_LABEL) break;
      switch(c)
      {
       case BinDrvReader.CTRL_OPENNDX:                    //  (
          System.out.print(" take("+bdrv.getString()+")="); // index
          bdrv.getControl();                              //  )
          System.out.println(bdrv.getReal());             //   value
          break;
       case BinDrvReader.CTRL_CLOSELST:                   // ]
          System.out.println(""); break;
       default:
          System.out.println("Unexpected Control");
          System.exit(0);
      }
     }
    }
    else if(s.equals("Objective"))
      System.out.println("Objective value = "+bdrv.getReal());
    else
    {
     System.out.println("Unexpected label "+s);
     System.exit(0);
    }
   }
  }
  else
  {
   System.out.println("Unexpected token");
   System.exit(1);
  }

  f.close();
 }