[hardwired]

Code:

C:\jexp>javac isalpha.java
isalpha.java:14: incompatible types
found   : boolean
required: char
        char n =  charinp.isAlphabetic(a);
                                      ^
1 error

The expression on the right side of the equals sign returns a boolean value. The declaration on the left is for a char. This is a type mismatch.
Try:

Code:

boolean n =  charinp.isAlphabetic(a);