CODEWITHSUNDEEP
javakotlin
james.sw.clark
james.sw.clark

Reputation: 357

Creating an ArrayList of unique items in an ArrayList

I would like my code to create an ArrayList (uniquePinyinArrayList) of unique items from an existing ArrayList (pinyinArrayList) which contains duplicates.

The "println" commands do not execute (I think they should do when a duplicate is from the pinyinArrayList is found in uniquePinyinArrayList)

fun uniquePinyinArray(pinyinArrayList: ArrayList<String>) {
    val uniquePinyinArrayList = ArrayList<String>()
    for(currentPinyin in pinyinArrayList){
        if (currentPinyin in uniquePinyinArrayList){
            // do nothing
            println("already contained"+currentPinyin)
            println("uniquePinyin"+uniquePinyinArrayList)
        }
        else {
            uniquePinyinArrayList.add(currentPinyin)
        }
    }
}

I have also tried 

if (uniquePinyinArrayList.contains(currentPinyin)){

, though this also didn't work.

Edit: This method actually gets run for each word from my list of source-words, and hence multiple ArrayLists are created. To fix this, I made a single ArrayList object for uniquePinyin outside of this loop. Things work as expected now!

Upvotes: 3

Views: 4209

Answers (2)

Sanket Patel
Sanket Patel

Reputation: 931

You can convert your array list to set.

 Set<String> foo = new HashSet<String>(pinyinArrayList);

Upvotes: 3

Todd
Todd

Reputation: 31700

Check out the distinct() function, it will do all of this for you!

fun main(args: Array<String>) {
    val listOfThings = listOf("A", "B", "C", "A", "B", "C")
    val distinctThings = listOfThings.distinct()

    println(listOfThings)  // [A, B, C, A, B, C]
    println(distinctThings)  // [A, B, C]
}

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/distinct.html

Upvotes: 6

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