java generate secure random password
public class PasswordUtils {
static char[] SYMBOLS = "^$*.[]{}()?-\"!@#%&/\\,><':;|_~`".toCharArray();
static char[] LOWERCASE = "abcdefghijklmnopqrstuvwxyz".toCharArray();
static char[] UPPERCASE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
static char[] NUMBERS = "0123456789".toCharArray();
static char[] ALL_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789^$*.[]{}()?-\"!@#%&/\\,><':;|_~`".toCharArray();
static Random rand = new SecureRandom();
public static String getPassword(int length) {
assert length >= 4;
char[] password = new char[length];
//get the requirements out of the way
password[0] = LOWERCASE[rand.nextInt(LOWERCASE.length)];
password[1] = UPPERCASE[rand.nextInt(UPPERCASE.length)];
password[2] = NUMBERS[rand.nextInt(NUMBERS.length)];
password[3] = SYMBOLS[rand.nextInt(SYMBOLS.length)];
//populate rest of the password with random chars
for (int i = 4; i < length; i++) {
password[i] = ALL_CHARS[rand.nextInt(ALL_CHARS.length)];
}
//shuffle it up
for (int i = 0; i < password.length; i++) {
int randomPosition = rand.nextInt(password.length);
char temp = password[i];
password[i] = password[randomPosition];
password[randomPosition] = temp;
}
return new String(password);
}
public static void main(String[] args) {
for (int i = 0; i < 100; i++) {
System.out.println(getPassword(8));
}
}
}