jodd.util.collection.CompositeEnumeration Maven / Gradle / Ivy
// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
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// 2. Redistributions in binary form must reproduce the above copyright
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package jodd.util.collection;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.NoSuchElementException;
/**
* Enumeration that combines multiple enumerations.
*/
public class CompositeEnumeration implements Enumeration {
protected final List> allEnumerations = new ArrayList<>();
/**
* Creates new composite enumeration.
* Enumerations may be added using the {@link #add(Enumeration)} method.
*/
public CompositeEnumeration() {
}
/**
* Creates new composite enumeration with provided enumerations.
*/
public CompositeEnumeration(final Enumeration... enumerations) {
for (Enumeration enumeration : enumerations) {
add(enumeration);
}
}
/**
* Adds an enumeration to this composite.
*/
public void add(final Enumeration enumeration) {
if (allEnumerations.contains(enumeration)) {
throw new IllegalArgumentException("Duplicate enumeration");
}
allEnumerations.add(enumeration);
}
// ---------------------------------------------------------------- interface
protected int currentEnumeration = -1;
/**
* Returns true if composite has more elements.
*/
public boolean hasMoreElements() {
if (currentEnumeration == -1) {
currentEnumeration = 0;
}
for (int i = currentEnumeration; i < allEnumerations.size(); i++) {
Enumeration enumeration = allEnumerations.get(i);
if (enumeration.hasMoreElements()) {
currentEnumeration = i;
return true;
}
}
return false;
}
/**
* {@inheritDoc}
*/
public T nextElement() {
if (!hasMoreElements()) {
throw new NoSuchElementException();
}
return allEnumerations.get(currentEnumeration).nextElement();
}
}