You haven't specified a scale for the result. Please try this

2019 Edit: Updated answer for JDK 13. Cause hopefully you've migrated off of JDK 1.5 by now.

import java.math.BigDecimal;
import java.math.RoundingMode;

public class Main {

    public static void main(String[] args) {
        BigDecimal a = new BigDecimal("1");
        BigDecimal b = new BigDecimal("3");
        BigDecimal c = a.divide(b, 2, RoundingMode.HALF_UP);
        System.out.println(a + "/" + b + " = " + c);
    }

}

Please read JDK 13 documentation.

Old answer for JDK 1.5 :

import java.math.*; 

    public class x
    {
      public static void main(String[] args)
      {
        BigDecimal a = new BigDecimal("1");
        BigDecimal b = new BigDecimal("3");
        BigDecimal c = a.divide(b,2, BigDecimal.ROUND_HALF_UP);
        System.out.println(a+"/"+b+" = "+c);
      }
    }

this will give the result as 0.33. Please read the API