为什么有时当我通过java中的isDigit方法检查字符是否为数字时，出现错误？

Question

If I have

Character.isDigit('53')

I get error

but if I have:

Character.isDigit('5')

I get a boolean value of TRUE.

Why is that so?

Answer 1

'5' is a character. '53' is not a character.

Or, to look at it in terms of strings, "5" is a string with one character in it ( '5' ), and "53" is a string with two characters in it ( '5' , '3' ).

Answer 2

A character is a single symbol. This means that '5' is a character, but since '53' has two symbols, it is not a character.

Answer 3

“ 5”和“ 53”都表示为字符串，其中第一个包含一个字符，第二个包含两个字符。