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A general programming library in Java

There is a newer version: 1.2.9

/*
 * Copyright (c) 2017, Haiyang Li.
 * 
 * Licensed 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 com.landawn.abacus.util;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * 
 * @since 0.9
 * 
 * @author Haiyang Li
 */
public abstract class ImmutableIterator implements java.util.Iterator {

    @SuppressWarnings("rawtypes")
    private static final ImmutableIterator EMPTY = new ImmutableIterator() {
        @Override
        public boolean hasNext() {
            return false;
        }

        @Override
        public Object next() {
            throw new NoSuchElementException();
        }
    };

    public static  ImmutableIterator empty() {
        return EMPTY;
    }

    public static  ImmutableIterator of(final Iterator iter) {
        if (iter == null) {
            return empty();
        } else if (iter instanceof ImmutableIterator) {
            return (ImmutableIterator) iter;
        }

        return new ImmutableIterator() {
            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public E next() {
                return iter.next();
            }
        };
    }

    /**
     * @deprecated - UnsupportedOperationException
     */
    @Deprecated
    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}