ChoiceFormat class can be used to get smallest possible Double value.

Java Code:
	    	 double d = 1.2;
	    	 double d1 = ChoiceFormat.previousDouble(d);
	    	 double d2 = ChoiceFormat.nextDouble(d);
	    	 System.out.println(d1);
	    	 System.out.println(d2);
Output:
Java Code:
1.1999999999999997
1.2000000000000002