In Java, is the result of the addition of two chars an int or a char?

by

The result of adding Java chars, shorts, or bytes is an int:

Java Language Specification on Binary Numeric Promotion:

  • If any of the operands is of a reference type, unboxing conversion
    (ยง5.1.8) is performed. Then:
  • If either operand is of type double, the
    other is converted to double.
  • Otherwise, if either operand is of type
    float, the other is converted to float.
  • Otherwise, if either operand
    is of type long, the other is converted to long.
  • Otherwise, both
    operands are converted to type int.

But note what it says about compound assignment operators (like +=):

The result of the binary operation is converted to the type of the left-hand variable … and the result of the conversion is stored into the variable.

For example:

char x = 1, y = 2;
x = x + y; // compile error: "possible loss of precision (found int, required char)"
x = (char)(x + y); // explicit cast back to char; OK
x += y; // compound operation-assignment; also OK

One way you can find out the type of the result, in general, is to cast it to an Object and ask it what class it is:

System.out.println(((Object)('a' + 'b')).getClass());
// outputs: class java.lang.Integer

If you’re interested in performance, note that the Java bytecode doesn’t even have dedicated instructions for arithmetic with the smaller data types. For example, for adding, there are instructions iadd (for ints), ladd (for longs), fadd (for floats), dadd (for doubles), and that’s it. To simulate x += y with the smaller types, the compiler will use iadd and then zero the upper bytes of the int using an instruction like i2c (“int to char”). If the native CPU has dedicated instructions for 1-byte or 2-byte data, it’s up to the Java virtual machine to optimize for that at run time.

If you want to concatenate characters as a String rather than interpreting them as a numeric type, there are lots of ways to do that. The easiest is adding an empty String to the expression, because adding a char and a String results in a String. All of these expressions result in the String "ab":

  • 'a' + "" + 'b'
  • "" + 'a' + 'b' (this works because "" + 'a' is evaluated first; if the "" were at the end instead you would get "195")
  • new String(new char[] { 'a', 'b' })
  • new StringBuilder().append('a').append('b').toString()
  • String.format("%c%c", 'a', 'b')

More Related Contents:

  1. Java: parse int value from a char
  2. Convert int to char in java
  3. Java – char, int conversions
  4. How does subtracting the character ‘0’ from a char change it into an int?
  5. negative char Value JAVA
  6. How can I convert a char to int in Java? [duplicate]
  7. Adding char and int
  8. Can assign integer value to char but can’t assign integer variable to char
  9. Using int vs Integer
  10. How can I prevent java.lang.NumberFormatException: For input string: “N/A”?
  11. What is the difference between Integer and int in Java?
  12. Java Array Sort descending?
  13. Check string for palindrome
  14. How to convert a char to a String?
  15. Is an array a primitive type or an object (or something else entirely)?
  16. Putting char into a java string for each N characters
  17. Convert boolean to int in Java
  18. Converting characters to integers in Java
  19. Java int to String – Integer.toString(i) vs new Integer(i).toString()
  20. What’s the default value of char?
  21. The concatenation of chars to form a string gives different results
  22. What does an integer that has zero in front of it mean and how can I print it?
  23. How to serialize Java primitives using Jersey REST
  24. Increment variable names? [duplicate]
  25. What is the best way to tell if a character is a letter or number in Java without using regexes?
  26. Are Java primitives immutable?
  27. Java: how much time does an empty loop use?
  28. How do I apply the for-each loop to every character in a String?
  29. Why is Java able to store 0xff000000 as an int?
  30. Converting an int array to a String array

Leave a Comment