To validate Social Security Numbers (SSN) using regular expressions in Java, you can use the following regular expression pattern:

String ssnPattern = "^(?!000|666)(?!9\\d{2})\\d{3}[- ]?(?!00)\\d{2}[- ]?(?!0000)\\d{4}$";

This regular expression pattern matches SSN codes in the following format:

• The first three digits cannot be "000" or "666".
• The second group of two digits cannot be "00".
• The third group of four digits cannot be "0000".
• The SSN may contain optional spaces or dashes.

To use this regular expression to validate an SSN code, you can use the following code:

String ssnCode = "123-45-6789";
if (ssnCode.matches(ssnPattern)) {
    System.out.println("Valid SSN code: " + ssnCode);
} else {
    System.out.println("Invalid SSN code: " + ssnCode);
}

In the example above, the "ssnCode" string is checked if it matches the "ssnPattern" regular expression. If it does, it is considered a valid SSN code.

Note that while this regular expression pattern is a good starting point for validating SSN codes, it may not catch all invalid codes. It's always a good idea to double-check any SSN codes entered by a user, and to use additional validation methods (such as checking the code against a database of valid SSN codes) to ensure the code is valid. Additionally, in real-world scenarios, you should also consider other factors such as the context and source of the SSN to ensure that it is being used appropriately and with consent.