Simplifying/optimizing massive if...else if...else statement(s)

Okay so essentially, I have some code that uses the contains() method to detect the presence of specific characters in two strings. For extra context, this question is a good resource as to what kind of problem I'm having (and the third solution is also something I've looked into for this). Regardless, here is some of my code:

// code up here basically just concatenates different
// characters to Strings: stringX and stringY

if (stringX.contains("!\"#")) {
} else if (stringX.contains("$%&")) {
} else if (stringX.contains("\'()")) {
} else if (stringX.contains("!$\'")) {
} else if (stringX.contains("\"%(")) {
// literally 70+ more else-if statements
}

if (stringY.contains("!\"#")) {
} else if (stringY.contains("$%&")) {
} else if (stringY.contains("\'()")) {
} else if (stringY.contains("!$\'")) {
} else if (stringY.contains("\"%(")) {
// literally 70+ more else-if statements, all of which are
// exactly the same as those working with stringX
}

I'm still pretty new to Java programming, so I'm not sure how I should go about this. Maybe it is a non-issue? Also, if I can remedy this without using RegEx, that would be preferable; I am not very knowledgeable in it at this point it time. But if the only rational solution would be to utilize it, I will obviously do so.

Edit: The code within all of these else-if statements will not be very different from each other at all; basically just a System.out.println() with some information about what characters stringX/stringY contains.

can simply by make a list of your case. then using java 8 stream filter

List<String> pattems = Arrays.asList("!\"#", "$%&", ...);
Optional<String> matched = pattems.stream().filter(p -> stringX.contains(p));
if(matched.isPresent()) {
   System.console().printf(matched.get())
}

java stream could make your peformance slower but not too much

Writing the same code more than once should immediately set off alarm bells in your head to move that code into a function so it can be reused.

As for simplifying the expression, the best approach is probably storing the patterns you're looking for as an array and iterating over the array with your condition.

private static final String[] patterns = new String[] {"!\"#", "$%&", "\'()", "!$\'", "\"%(", ...};

private static void findPatterns(String input) {
    for (String pattern : patterns) {
        if (input.contains(pattern) {
            System.out.println("Found pattern: " + pattern);
        }
    }
}

// Elsewhere...
findPatterns(stringX);
findPatterns(stringY);

This pattern is especially common in functional and functional-style languages. Java 8 streams are a good example, so you could equivalently do

List<String> patterns = Arrays.asList("!\"#", "$%&", "\'()", "!$\'", "\"%(", ...);
patterns.stream()
    .filter(pattern -> stringX.contains(pattern))
    .forEach(pattern -> System.out.println("Found pattern: " + pattern));