cn.hutool.core.collection.IterChain Maven / Gradle / Ivy
package cn.hutool.core.collection;
import cn.hutool.core.lang.Chain;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* 组合{@link Iterator}，将多个{@link Iterator}组合在一起，便于集中遍历。
* 来自Jodd
*
* @param 元素类型
* @author looly, jodd
*/
public class IterChain implements Iterator, Chain, IterChain> {
protected final List> allIterators = new ArrayList<>();
/**
* 构造
* 可以使用 {@link #addChain(Iterator)} 方法加入更多的集合。
*/
public IterChain() {
}
/**
* 构造
* @param iterators 多个{@link Iterator}
*/
@SafeVarargs
public IterChain(Iterator... iterators) {
for (final Iterator iterator : iterators) {
addChain(iterator);
}
}
@Override
public IterChain addChain(Iterator iterator) {
if (allIterators.contains(iterator)) {
throw new IllegalArgumentException("Duplicate iterator");
}
allIterators.add(iterator);
return this;
}
// ---------------------------------------------------------------- interface
protected int currentIter = -1;
@Override
public boolean hasNext() {
if (currentIter == -1) {
currentIter = 0;
}
final int size = allIterators.size();
for (int i = currentIter; i < size; i++) {
final Iterator iterator = allIterators.get(i);
if (iterator.hasNext()) {
currentIter = i;
return true;
}
}
return false;
}
@Override
public T next() {
if (false == hasNext()) {
throw new NoSuchElementException();
}
return allIterators.get(currentIter).next();
}
@Override
public void remove() {
if (-1 == currentIter) {
throw new IllegalStateException("next() has not yet been called");
}
allIterators.get(currentIter).remove();
}
@Override
public Iterator> iterator() {
return this.allIterators.iterator();
}
}