iterator Union - Java java.util

Java examples for java.util:Iterator

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Description

iterator Union

Demo Code

/*//from www. j a  v  a 2s .  c o  m
    GNU LESSER GENERAL PUBLIC LICENSE
    Copyright (C) 2006 The Lobo Project. Copyright (C) 2014 - 2015 Lobo Evolution

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Contact info: lobochief@users.sourceforge.net; ivan.difrancesco@yahoo.it
 */
//package com.book2s;

import java.util.Iterator;

import java.util.NoSuchElementException;

public class Main {
    public static Iterator iteratorUnion(final Iterator[] iterators) {
        return new Iterator() {
            private int iteratorIndex = 0;
            private Iterator current = iterators.length > 0 ? iterators[0]
                    : null;

            public boolean hasNext() {
                for (;;) {
                    if (current == null) {
                        return false;
                    }
                    if (current.hasNext()) {
                        return true;
                    }
                    iteratorIndex++;
                    current = iteratorIndex >= iterators.length ? null
                            : iterators[iteratorIndex];
                }
            }

            public Object next() {
                for (;;) {
                    if (this.current == null) {
                        throw new NoSuchElementException();
                    }
                    try {
                        return this.current.next();
                    } catch (NoSuchElementException nse) {
                        this.iteratorIndex++;
                        this.current = this.iteratorIndex >= iterators.length ? null
                                : iterators[this.iteratorIndex];
                    }
                }
            }

            public void remove() {
                if (this.current == null) {
                    throw new NoSuchElementException();
                }
                this.current.remove();
            }
        };
    }
}

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