jodd.util.collection.CompositeIterator Maven / Gradle / Ivy
// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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package jodd.util.collection;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Iterator that combines multiple iterators.
*/
public class CompositeIterator implements Iterator {
protected final List> allIterators = new ArrayList<>();
/**
* Creates new composite iterator.
* Iterators may be added using the {@link #add(Iterator)} method.
*/
public CompositeIterator() {
}
/**
* Creates new composite iterator with provided iterators.
*/
public CompositeIterator(final Iterator... iterators) {
for (Iterator iterator : iterators) {
add(iterator);
}
}
/**
* Adds an iterator to this composite.
*/
public void add(final Iterator iterator) {
if (allIterators.contains(iterator)) {
throw new IllegalArgumentException("Duplicate iterator");
}
allIterators.add(iterator);
}
// ---------------------------------------------------------------- interface
protected int currentIterator = -1;
/**
* Returns true if next element is available.
*/
@Override
public boolean hasNext() {
if (currentIterator == -1) {
currentIterator = 0;
}
for (int i = currentIterator; i < allIterators.size(); i++) {
Iterator iterator = allIterators.get(i);
if (iterator.hasNext()) {
currentIterator = i;
return true;
}
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public T next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return allIterators.get(currentIterator).next();
}
/**
* {@inheritDoc}
*/
@Override
public void remove() {
if (currentIterator == -1) {
throw new IllegalStateException("next() has not yet been called");
}
allIterators.get(currentIterator).remove();
}
}