LESSON 166 OF 410 · PROJECTS: EVERYDAY PROGRAMS

Password Strength V3 - Character Classes in Java

Practice

Track four boolean flags for a password: does it contain an uppercase letter, a lowercase letter, a digit, and a symbol (non-alphanumeric)?

You start with:

String password = "Secret!99";

Build:

Length: 9
Upper: True
Lower: True
Digit: True
Symbol: True
Strong

Rules:

Print "Length: " followed by the number of characters.
Start four flags (hasUpper, hasLower, hasDigit, hasSymbol) at false. Loop over every character and set the matching flag to true.
A symbol is any character that is not a letter and not a digit.
Print one line per flag, in this order: "Upper: ", "Lower: ", "Digit: ", "Symbol: ", each followed by the flag. Write it as True or False with a capital letter, exactly as in the example (your language's own boolean prints differently, so choose the text yourself).
If the length is at least 8 and all four flags are true (stricter than the last lesson), print Strong; otherwise print Weak.

Try other passwords: with secret99 the output is

Length: 8
Upper: False
Lower: True
Digit: True
Symbol: False
Weak

Use Character.isUpperCase(c), isLowerCase, isDigit, isLetterOrDigit in password.toCharArray().

String password = "Secret!99";

int length = password.length();
System.out.println("Length: " + length);
boolean hasUpper = false;
boolean hasLower = false;
boolean hasDigit = false;
boolean hasSymbol = false;
for (char c : password.toCharArray()) {
    if (Character.isUpperCase(c)) {
        hasUpper = true;
    }
    if (Character.isLowerCase(c)) {
        hasLower = true;
    }
    if (Character.isDigit(c)) {
        hasDigit = true;
    }
    if (!Character.isLetterOrDigit(c)) {
        hasSymbol = true;
    }
}
System.out.println("Upper: " + (hasUpper ? "True" : "False"));
System.out.println("Lower: " + (hasLower ? "True" : "False"));
System.out.println("Digit: " + (hasDigit ? "True" : "False"));
System.out.println("Symbol: " + (hasSymbol ? "True" : "False"));
if (length >= 8 && hasUpper && hasLower && hasDigit && hasSymbol) {
    System.out.println("Strong");
} else {
    System.out.println("Weak");
}

STEP 1 OF 13

Guided

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Password Strength V3 - Character Classes in Java

Password Strength V3 in Java