Why does concatenated characters print a number?

In the second case it adds the unicode codes of the two characters (G - 71 and o - 111) and prints the sum. This is because char is considered as a numeric type, so the + operator is the usual summation in this case.

+ operator with character constant 'G' + 'o' prints addition of charCode and string concatenation operator with "G" + "o" will prints Go.

The plus in Java adds two numbers, unless one of the summands is a String, in which case it does string concatenation.

In your second case, you don't have Strings (you have char, and their Unicode code points will be added).