Is there a concise way to iterate over a stream with indices in Java 8?

Question

Is there a concise way to iterate over a stream whilst having access to the index in the stream?

String[] names = {\"Sam\",\"Pamela\", \"Dave\", \"Pascal\",          


        

Answer 1

If you need the index in the forEach then this provides a way.

  public class IndexedValue {

    private final int    index;
    private final Object value;

    public IndexedValue(final int index, final Object value) { 
        this.index = index;
        this.value = value;
    }

    public int getIndex() {
        return index;
    }

    public Object getValue() {
        return value;
    }
}

Then use it as follows.

@Test
public void withIndex() {
    final List list = Arrays.asList("a", "b");
    IntStream.range(0, list.size())
             .mapToObj(index -> new IndexedValue(index, list.get(index)))
             .forEach(indexValue -> {
                 System.out.println(String.format("%d, %s",
                                                  indexValue.getIndex(),
                                                  indexValue.getValue().toString()));
             });
}