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    • com.arangodb.util.CollectionUtils Maven / Gradle / Ivy

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    /*
 * Copyright (C) 2012 tamtam180
 *
 * 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.arangodb.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

/**
 * @author tamtam180 - kirscheless at gmail.com
 *
 */
public class CollectionUtils {

  public static class EmptyIterator implements Iterator {
    public boolean hasNext() {
      return false;
    }
    public E next() {
      throw new NoSuchElementException();
    }
    public void remove() {
      throw new IllegalStateException();
    }
  }
  
  private static final EmptyIterator EMPTY_ITERATOR = new EmptyIterator();
  
  @SuppressWarnings("unchecked")
  public static  Iterator emptyIterator() {
    return (Iterator) EMPTY_ITERATOR;
  }
  
  public static  Iterator safetyIterator(Collection collection) {
    if (collection == null) {
      return emptyIterator();
    }
    return collection.iterator();
  }
  
  public static  List safety(List list) {
    if (list == null) {
      return new ArrayList(0); // mutable list
    }
    return list;
  }
  
  public static  String join(T[] array, String separator) {
    if (array == null || array.length == 0) {
      return "";
    }
    
    StringBuilder buffer = new StringBuilder();
    buffer.append(array[0]);
    
    for (int i = 1; i < array.length; i++) {
      buffer.append(separator);
      buffer.append(array[i]);
    }
    
    return buffer.toString();
  }
  
  public static boolean isNotEmpty(final Collection coll) {
    return coll != null && !coll.isEmpty();
  }
  
}
    
    
    
    

    




    
    
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