Merge pull request #147 from madhurajayashanka/madhura

added password generator using java best practices

Author: kishanrajput23

RandomPasswordGenerator/PasswordGenerator.java

@@ -0,0 +1,52 @@
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.util.Random;
+
+public class PasswordGenerator {
+    private static final String UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    private static final String LOWER = "abcdefghijklmnopqrstuvwxyz";
+    private static final String DIGITS = "0123456789";
+    private static final String SPECIAL = "!@#$%^&*()-_=+[]{}|;:'\",.<>?";
+
+    public static String generatePassword(int length, boolean useUpper, boolean useLower, boolean useDigits, boolean useSpecial) {
+        if (length <= 0) {
+            throw new IllegalArgumentException("Password length must be greater than 0");
+        }
+
+        StringBuilder characters = new StringBuilder();
+        if (useUpper) characters.append(UPPER);
+        if (useLower) characters.append(LOWER);
+        if (useDigits) characters.append(DIGITS);
+        if (useSpecial) characters.append(SPECIAL);
+
+        if (characters.length() == 0) {
+            throw new IllegalArgumentException("At least one character type (upper, lower, digits, special) must be selected");
+        }
+
+        Random random;
+        try {
+            random = SecureRandom.getInstanceStrong(); // Strong cryptographic random number generator
+        } catch (NoSuchAlgorithmException e) {
+            random = new SecureRandom();
+        }
+
+        StringBuilder password = new StringBuilder(length);
+        for (int i = 0; i < length; i++) {
+            int randomIndex = random.nextInt(characters.length());
+            password.append(characters.charAt(randomIndex));
+        }
+
+        return password.toString();
+    }
+
+    public static void main(String[] args) {
+        int length = 12; // Change the desired password length
+        boolean useUpper = true;
+        boolean useLower = true;
+        boolean useDigits = true;
+        boolean useSpecial = true;
+
+        String password = generatePassword(length, useUpper, useLower, useDigits, useSpecial);
+        System.out.println("Generated Password: " + password);
+    }
+}