Call to super must be first statement

Question

I'm new to Java and I have a question regarding super(). I'm implementing a design where we have a custom exception which extends Exception. The design calls for null messages to lead to throwing an IllegalArgumentException, but Exception's constructor does not throw an IllegalArgumentException for a null message.
Here is what I want to do, but not allowed to since super must be the first statement in the constructor:
public CustomException(String message) {
    if (message == null) {
        throw new IllegalArgumentException("message cannot be null.");
    super(message);
}I could call super first and then throw an exception if the message is null, but that doesn't seem like a good solution.

Answer 1

public CustomException(String message) {
    super(nullCheck(message));
static String nullCheck(String message) {
    if (message == null) {
        throw new IllegalArgumentException("message cannot be null.");
    return message;
}