Iterators.java

package net.aquadc.util;

import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.Iterator;
import java.util.function.Consumer;
import java.util.stream.Stream;

public final class Iterators {
    private Iterators() {}

    public static <T> Iterator<T> ofStream(Stream<? extends T> stream) {
        return new AutoCloseIterator<T>(stream.iterator(), stream);
    }
    private static final class AutoCloseIterator<T> implements Iterator<T> {
        private final Iterator<? extends T> iterator;
        private final AutoCloseable closeable;
        private AutoCloseIterator(Iterator<? extends T> iterator, AutoCloseable closeable) {
            this.iterator = iterator;
            this.closeable = closeable;
        }
        @Override public boolean hasNext() {
            return iterator.hasNext();
        }
        @Override public T next() {
            T next = iterator.next();
            if (!iterator.hasNext()) close();
            return next;
        }
        @Override public void remove() {
            iterator.remove();
        }
        @Override public void forEachRemaining(Consumer<? super T> action) {
            iterator.forEachRemaining(action);
            close();
        }
        private void close() {
            try { closeable.close(); }
            catch (IOException e) { throw new UncheckedIOException(e); }
            catch (RuntimeException e) { throw e; }
            catch (Exception e) { throw new RuntimeException(e); }
        }
    }
}