Question

I tried the below, but Eclipse throws an error for this.

while((s.charAt(j)== null)

What’s the correct way of checking whether a character is null?

Answer 1

Check that the String s is not null before doing any character checks. The characters returned by String#charAt are primitive char types and will never be null:

if (s != null) {
  ...

If you’re trying to process characters from String one at a time, you can use:

for (char c: s.toCharArray()) {
   // do stuff with char c  
}

(Unlike C, NULL terminator checking is not done in Java.)