Passing variable to an exception

	private static void ignoringExc(RunnableExc r) {
		try {
			r.run();
		} catch (Exception e) {
			log.error("");
		}
	}

	@FunctionalInterface
	private interface RunnableExc {
		void run() throws Exception;
	}

I have multiple variables that need to be set into a Person a. However, some variables from Person b may be null. So I use the above function to avoid null pointer exception error. But I want to customise the error message in log.error() in ignoringExc function, such as "The age of Person B is null". How to do that?

ignoringExc(() -> a.setAddress(b.getPerson("address")));
ignoringExc(() -> a.setName(b.getPerson("name")));
ignoringExc(() -> a.setAge(b.getPerson("age")));
...

You shouldn't be using NullPointerException to do null checks. Throwing an exception is relatively expensive, as @user16320675 points out, other NPE's may occur, and you are also catching Exception which will ignore other problems.

Instead, use a function like:

    static <T> void setIfNotNull(T value, Consumer<T> setter) {
        if (value != null) {
            setter.accept(value);
        } else {
            // logging if needed
        }
    }

and call it like this:

        setIfNotNull(b.getName(), a::setName);

Of course you could also consider making the setters on A silently ignore null instead of throwing an exception, but that depends on your requirements.

You could pass in a String as well. This is common practice for some of the precondition tools in Java. Take a look at Objects#requireNonNull(T) vs Objects#requireNonNull(T,String).

So, like this.

    private static void ignoringExc(RunnableExc r, String message) {
        try {
            r.run();
        } catch (Exception e) {
            log.error(message);
        }
    }

    @FunctionalInterface
    private interface RunnableExc {
        void run() throws Exception;
    }

Which would then allow you to do this.

ignoringExc(() -> a.setAddress(b.getPerson("address")), "address message");
ignoringExc(() -> a.setName(b.getPerson("name")),       "name message");
ignoringExc(() -> a.setAge(b.getPerson("age")),         "age message");
...