Question

it may be a nooby question, but I’ve never needed it before:

I have several strings and I want to compare them to given ones…

At first glance it would lead to a switch/case construction in what every available entry is checked.

Is there a more elegant way to swap those strings as key/value datas?

greets,
poeschlorn

Answer 1

Update: My bad. I misread this as case insensitive search.

Case sensitive is easy. Java does not yet support Strings in switch statements. The easiest solution is:

if (string1.equals(string2)) {
  ...
} else if (string1.equals(string3)) {
  ...
}

Or as a loop:

String[] matches = new String[] {
  "abcd",
  "efgh",
  "ijkl"
};

for (String match : matches) {
  if (matches.equals(string)) {
    ...
  }
}

Of course, this is linear (O(n)) and doesn’t scale but is simple and is sufficient for the simplest of cases. A better solution is to use a hash-based lookup:

Set<String> matches = new HashSet<String>();
matches.add("abcd");
matches.add("efgh");
matches.add("ijkl");

if (matches.contains(string1)) {
  ...
}

This is near-linear (O(1)) lookup and will scale much better with a large number of Strings.