NextValCyclicFetcher v1.0

Fetch your java.util.List’s next element and restart from the first element automatically, when no more elements left available.

Code

package util;

import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;


public class NextValCyclicFetcher<T> {

  private List<T> list;
  private Iterator<T> iterator;

  public NextValCyclicFetcher(List<T> list) {
    if (null == list) {
      throw new IllegalArgumentException("null");
    }

    if (list.isEmpty()) {
      throw new IllegalArgumentException("empty");
    }

    this.list = list.stream().collect(Collectors.toList());
    this.iterator = this.list.iterator();
  }

  public T next() {
    if (iterator.hasNext()) {
      return iterator.next();
    }

    iterator = list.iterator();
    return next();
  }
}

It uses standard Java 8 imports.

The passed in List is copied so that if the original list is modified outside the cyclic fetcher, the cyclic fetcher will continue working as expected.

Example

public void exampleMethod() {
  List<String> list = Arrays.asList("first", "second", "third");
  NextValCyclicFetcher<String> listCyclicFetcher = new NextValCyclicFetcher<>(list);

  // more code

  while (condition) {    
    String string = listCyclicFetcher.next();
    System.out.println(string);
  }
}

Output

first
second
third
first
second
third
first
...
(Until condition is not satisfied anymore)