org.tomitribe.util.collect.AbstractIterator Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.tomitribe.util.collect;
import java.util.Iterator;
import java.util.NoSuchElementException;
public abstract class AbstractIterator implements Iterator {
private T next;
@Override
public boolean hasNext() {
if (next != null) return true;
try {
next = advance();
return next != null;
} catch (final NoSuchElementException e) {
return false;
}
}
@Override
public T next() {
if (!hasNext()) throw new NoSuchElementException();
final T v = next;
next = null;
return v;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
protected abstract T advance() throws NoSuchElementException;
}