Return first digit of an integer

by

The easiest way would be to use String.valueOf(Math.abs((long)x)).charAt(0) – that will give it you as a char1. To get that as an integer value, you could just subtract ‘0’ (as in Unicode, ‘0’ to ‘9’ are contiguous).

It’s somewhat wasteful, of course. An alternative would just be to take the absolute value, then loop round dividing by 10 until the number is in the range 0-9. If this is homework, that’s the answer I’d give. However, I’m not going to provide the code for it because I think it might be homework. However, if you provide comments and edit your answer to explain how you’re doing and what problems you’re running into, we may be able to help.

1One sticky point to note is that the absolute value of Integer.MIN_VALUE can’t be represented as an int – so you may should first convert to a long, then use Math.abs, then do arithmetic. That’s why there’s a cast there.

More Related Contents:

  1. Determine if a String is an Integer in Java [duplicate]
  2. Why is 08 not a valid integer literal in Java?
  3. How can I prevent java.lang.NumberFormatException: For input string: “N/A”?
  4. Java: parse int value from a char
  5. Java – Convert integer to string [duplicate]
  6. What is the difference between Integer and int in Java?
  7. Java Array Sort descending?
  8. Why do these two multiplication operations give different results?
  9. Java – char, int conversions
  10. The literal xyz of type int is out of range
  11. How to convert float to int with Java
  12. “int cannot be dereferenced” in Java
  13. Convert boolean to int in Java
  14. How are integers cast to bytes in Java?
  15. Converting an int to a binary string representation in Java?
  16. Rounding a double to turn it into an int (java)
  17. Java int to String – Integer.toString(i) vs new Integer(i).toString()
  18. What does an integer that has zero in front of it mean and how can I print it?
  19. Integer vs int: with regard to memory
  20. Is it valid to compare a double with an int in java?
  21. Splitting String and put it on int array
  22. How does subtracting the character ‘0’ from a char change it into an int?
  23. Java – Change int to ascii
  24. How can I convert a char to int in Java? [duplicate]
  25. Adding char and int
  26. Why is Java able to store 0xff000000 as an int?
  27. Can assign integer value to char but can’t assign integer variable to char
  28. int[] and Integer[] arrays – What is the difference?
  29. Integer division in Java [duplicate]
  30. How do I convert from int to Long in Java?

Leave a Comment