Concise update for Java SE 9

Reference arrays are bad. For this case we are after a set. Since Java SE 9 we have Set.of.

private static final Set<String> VALUES = Set.of(
    "AB","BC","CD","AE"
);

"Given String s, is there a good way of testing whether VALUES contains s?"

VALUES.contains(s)

O(1).

The right type, immutable, O(1) and concise. Beautiful.*

Original answer details

Just to clear the code up to start with. We have (corrected):

public static final String[] VALUES = new String[] {"AB","BC","CD","AE"};

This is a mutable static which FindBugs will tell you is very naughty. Do not modify statics and do not allow other code to do so also. At an absolute minimum, the field should be private:

private static final String[] VALUES = new String[] {"AB","BC","CD","AE"};

(Note, you can actually drop the new String[]; bit.)

Reference arrays are still bad and we want a set:

private static final Set<String> VALUES = new HashSet<String>(Arrays.asList(
     new String[] {"AB","BC","CD","AE"}
));

(Paranoid people, such as myself, may feel more at ease if this was wrapped in Collections.unmodifiableSet - it could then even be made public.)

(*To be a little more on brand, the collections API is predictably still missing immutable collection types and the syntax is still far too verbose, for my tastes.)

What would you do, programming set aside, with a paper and a pen, to perform that operation manually? Considering that the list can be much bigger than 10 elements, you need a systematic approach.

You would probably look at each element of the list, one after the other, and compare that element with the number you are looking for.

Looking at each element of a list is what a loop does.

Testing and comparing usually involves relational operators, like ==, or <

So, you need to loop through all the elements, compare them with the value you are looking for using the right operator, and test the result of that comparison:

for (int value: arraynumbers) {
    if (value == num) {
        // Here you found the number you are looking for
    }
}

Just write two for loops and check whether any given element in one array is in the other. So just:

for (int i=0; i< portOut.length; i++){
   for(int j=0;j<result.length;j++) {
      //rest of code
   }
}

Write a static function

public static boolean indexInBound(String[] data, int index){
    return data != null && index >= 0 && index < data.length;
}

Now, give it a call in your code

if(indexInBound(ImageLinks, 5) && ImageLinks[5] != null){
   //Your Code
}