org.wildfly.common.iteration.CompositeIterator Maven / Gradle / Ivy
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* Copyright 2019 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wildfly.common.iteration;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Consumer;
/**
* Iterator that iterates over a series of iterators.
* @author Paul Ferraro
*/
public class CompositeIterator implements Iterator {
private final Iterable> iterators;
private Iterator lastIterator;
/**
* Constructs a new composite iterator.
* @param iterators a series of iterators
*/
@SafeVarargs
public CompositeIterator(Iterator... iterators) {
this(Arrays.asList(iterators));
}
/**
* Constructs a new composite iterator.
* @param iterators a series of iterators
*/
public CompositeIterator(Iterable> iterators) {
this.iterators = iterators;
}
@Override
public boolean hasNext() {
for (Iterator iterator : this.iterators) {
if (iterator.hasNext()) return true;
}
return false;
}
@Override
public E next() {
for (Iterator iterator : this.iterators) {
if (iterator.hasNext()) {
this.lastIterator = iterator;
return iterator.next();
}
}
throw new NoSuchElementException();
}
@Override
public void remove() {
Iterator iterator = this.lastIterator;
if (iterator == null) {
throw new IllegalStateException();
}
iterator.remove();
}
@Override
public void forEachRemaining(Consumer action) {
for (Iterator iterator : this.iterators) {
while (iterator.hasNext()) {
action.accept(iterator.next());
}
}
}
}