+ * ( # Start of group
+ * (?=.*[a-z,A-Z]) # must contain one character
+ *
+ * (?=.*\d) # must contain one digit from 0-9
+ * OR
+ * (?=.*[@#$%]) # must contain one special symbols in the list SPEC_CHARS
+ *
+ * . # match anything with previous condition checking
+ * {6,20} # length at least 6 characters and maximum of 20
+ * ) # End of group
+ *
+ * Another example, more stringent pattern
+ private static final Pattern PASS_PATTERN=Pattern.compile("((?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[" + SPEC_CHARS +"]).{6,20})");