Question

I am doing an application where I want to find a specific char in an array of chars. In other words, I have the following char array:

char[] charArray= new char[] {'\uE001', '\uE002', '\uE003', '\uE004', '\uE005', '\uE006', '\uE007', '\uE008', '\uE009'};

At some point, I want to check if the character '\uE002' exists in the charArray. My method was to make a loop on every character in the charArray and find if it exists.

for (int z = 0 ; z < charArray; z ++) {
    if (charArray[z] == myChar) {
        //Do the work
    }
}

Is there any other solution than making a char array and finding the character by looping every single char?

Answer 1

One option is to pre-sort charArray and use Arrays.binarySearch(charArray, myChar). A non-negative return value will indicate that myChar is present in charArray.

char[] charArray = new char[] {'\uE001', '\uE002', '\uE003', '\uE004', '\uE005', '\uE006', '\uE007', '\uE008', '\uE009'};
Arrays.sort(charArray); // can be omitted if you know that the values are already sorted
...
if (Arrays.binarySearch(charArray, myChar) >= 0) {
  // Do the work
}

edit An alternative that avoids using the Arrays module is to put the characters into a string (at initialization time) and then use String.indexOf():

String chars = "\uE001...";
...
if (chars.indexOf(myChar) >= 0) {
   // Do the work
}

This is not hugely different to what you’re doing already, except that it requires less code.

If n is the size of charArray, the first solution is O(log n) whereas the second one is O(n).