Checking letter case (Upper/Lower) within a string in Java

Question

The problem that I am having is that I can\'t get my Password Verification Program to check a string to ensure that, 1 of the characters is in upper case and one is in lower

Answer 1

This is quite old and @SinkingPoint already gave a great answer above. Now, with functional idioms available in Java 8 we could give it one more twist. You would have two lambdas:

Function hasLowerCase = s -> s.chars().filter(c -> Character.isLowerCase(c)).count() > 0;
Function hasUpperCase = s -> s.chars().filter(c -> Character.isUpperCase(c)).count() > 0;

Then in code we could check password rules like this:

if (!hasUppercase.apply(password)) System.out.println("Must have an uppercase Character");
if (!hasLowercase.apply(password)) System.out.println("Must have a lowercase Character");

As to the other checks:

Function isAtLeast8 = s -> s.length() >= 8; //Checks for at least 8 characters
Function hasSpecial   = s -> !s.matches("[A-Za-z0-9 ]*");//Checks at least one char is not alpha numeric
Function noConditions = s -> !(s.contains("AND") || s.contains("NOT"));//Check that it doesn't contain AND or NOT

In some cases, it is arguable, whether creating the lambda adds value in terms of communicating intent, but the good thing about lambdas is that they are functional.