Reputation: 1659

Zipping a list of strings in java

What would be the easiest / quickest way to zip a list of strings which is similar to this:

john,barry,stewart,josh,30,45,23,56

I want the order to be

john,30,barry,45,stewart,23,josh,56

I know that sounds like homework but the actual list is used in some selenium code and stores urls and the option of a radio button on the page but I thought the above example is simpler to read.

Upvotes: 1

Answers (8)

Yaneeve

Reputation: 4779

It seems as if you are just trying to interleave the numbers and the alphanumerics. I would just scan the list in order to find the index of the first number than create a new list and take the first alpha and the first number and add them to the new list, then the second alpha and second number. This is not sorting and so is O(n)

Upvotes: 0

tucuxi

Reputation: 17945

Generic version of zip:

@SafeVarargs
public static <T> ArrayList<T> zip(Iterable<T>  ...iterables) {
    ArrayList<Iterator<T>> is = new ArrayList<>(iterables.length);
    for (int i=0; i<iterables.length; i++) {
        is.add(iterables[i].iterator());
    }
    ArrayList<T> al = new ArrayList<>();
    while (is.get(0).hasNext()) {
        for (int i=0; i<is.size(); i++) {
            // FIXME: could check for shorter-than-expected sublists here
            al.add(is.get(i).next());
        }
    }
    return al;
}

Can be tested / called as follows:

public static void main(String[] args) {
    List<String> parts = 
            Arrays.asList("john,barry,stewart,josh,30,45,23,56".split(","));
    List<String> names = parts.subList(0, parts.size()/2);
    List<String> numbers = parts.subList(parts.size()/2, parts.size());
    System.err.println(zip(names, numbers));
}

Upvotes: 0

Nishant Lakhara

Reputation: 2445

Try this way : 1. First sort it - the numbers will cover half the list and names half the list. 2. Create two arrays half the length : sArr1 and sArr2. Store numbers in sArr1 and names in sArr2. 3. Merge them by putting alternatively the number and the name from the two arrays into original array.

import java.util.Arrays;


public class SortMix {
    public static void main(String[] args) {
        String sArr[] = {"john","barry","stewart","josh","30","45","23","56"};
        Arrays.sort(sArr);
        display(sArr);

        String sArr1[] = new String[sArr.length/2];
        for(int i=0;i<sArr.length/2;i++) 
            sArr1[i] = sArr[i];
        display(sArr1);

        String sArr2[] = new String[sArr.length/2];
        for(int i=0;i<sArr.length/2;i++)
            sArr2[i] = sArr[i+sArr.length/2];
        display(sArr2);

        int k=0;
        int l=0;
        for(int i=0;i<sArr.length;i++) {
            if(i%2==0){ 
                sArr[i]=sArr1[k];
                k++;    
            } else {
                sArr[i]=sArr2[l];
                l++;
            }
        }
        display(sArr);
    }

    public static void display(String[] sArr) {
        for(int i=0;i<sArr.length;i++) 
            System.out.print(sArr[i] + " ");
        System.out.println();
    }
}

Output would be :

23 30 45 56 barry john josh stewart 
23 30 45 56 
barry john josh stewart 
23 barry 30 john 45 josh 56 stewart

Upvotes: 0

Ingo

Reputation: 36349

Your question sounds like you need code to fix a bad design. Therefore, I would go a step back and ask the question how the list

john,barry,stewart,josh,30,45,23,56

was created, when you obviously need:

(john, 30), (barry, 45), (stewart, 23), (josh, 56)

(Replace the (x,y) notation with you favorite tuple type.)

Upvotes: 1

BambooleanLogic

Reputation: 8171

I would do something similar to this:

String[] parts = input.split(",");
int halfLength = parts.length / 2;
for (int i = 0; i < halfLength; i++) {
    String name = parts[i];
    String age = parts[i + halfLength];
    // Store them in whatever structure you want here
}

Upvotes: 6

urbiwanus

Reputation: 723

Looks like two lists

First generate two lists and create a new result list

Pseudocode :

list = Arrays.AsList(string.split("\\s+"))

list1 = list.sublist(0, list.size() /2 );
list2 = list.sublist(list.size() /2 +1 , list.size());

for(int i = 0;i<list1.size() ; i++ ) {
   resultlist.add(list1.get(i);
   resultlist.add(list2.get(i);
}
return resultlist

Upvotes: 0