check if char is int code example

Example 1: check if char is number java

Character.isDigit(str.charAt(i));

Example 2: c check if char is number

char c = 'a'; // or whatever

if (isalpha(c)) {
    puts("it's a letter");
} else if (isdigit(c)) {
    puts("it's a digit");
} else {
    puts("something else?");
}