de.invation.code.toval.misc.CollectionUtils Maven / Gradle / Ivy

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package de.invation.code.toval.misc;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Formatter;
import java.util.Iterator;
import java.util.List;

import de.invation.code.toval.reflect.GenericReflection;


public class CollectionUtils {
	
	/**
	 * String for value separation.

	 * Used for generating String representations of collections.
	 */
	public static final String VALUE_SEPARATION = ", ";
	
	public static final String DEFAULT_START = "[";
	public static final String DEFAULT_END = "]";
	/**
	 * Default precision used for String representations of collection elements
	 * having type Float or Double.
	 */
	public static final int DEFAULT_PRECISION = 2;
	/**
	 * String representation for empty arrays.
	 */
	public static final String EMPTY_COLLECTION = "[]";

	/**
	 * Checks if the given basic list contains any element of the given value list.
	 * @param  Type of collection elements
	 * @param baseList List to check for occurrences
	 * @param valueList Values to search
	 * @return true if baseList contains any element of valueList;
	 * false otherwise
	 */
	public static  boolean containsNo(Collection baseList, Collection valueList) {
		for(T v: valueList) {
			if(baseList.contains(v)) {
				return false;
			}
		}
		return true;
	}
	
	public static  List> randomPartition(Collection coll, int number){
		return ListUtils.randomPartition(new ArrayList(coll), number);
	}
	
	public static  List>exponentialPartition(Collection coll, int number){
		return ListUtils.exponentialPartition(new ArrayList(coll), number);
	}
	
	/**
	 * Returns a String representation of a Collection.

	 * @param coll Collection for String representation
	 * @return String representation of coll
	 * @see CollectionUtils#getFormat(Collection, int, String, String, String)
	 */
	public static String toString(Collection coll) {
		return toString(coll, DEFAULT_PRECISION);
	}
	
	/**
	 * Returns a String representation of a Collection.

	 * The specified precision is only applicable for Float and Double elements.
	 * @param coll Collection for String representation
	 * @param precision Desired precision for Float and Double elements
	 * @return String representation of coll
	 * @see CollectionUtils#getFormat(Collection, int, String, String, String)
	 */
	public static String toString(Collection coll, int precision) {
		if(coll == null)
			throw new NullPointerException();
		if(coll.isEmpty())
			return EMPTY_COLLECTION;
		return String.format(getFormat(coll, precision), coll.toArray());
	}
	
	/**
	 * Returns a format-String that can be used to generate a String representation of a collection
	 * using the String.format method.
	 * @param coll Collection for which a String representation is desired
	 * @param precision Desired precision for Float and Double elements
	 * @return Format-String for coll
	 * @see Formatter
	 * @see String#format(String, Object...)
	 */
	private static String getFormat(Collection coll, int precision) {
		return getFormat(coll, precision, VALUE_SEPARATION, "[", "]");
	}
	
	public static String getFormat(Collection coll, int precision, String valueSeparation, String start, String end) {
		StringBuilder builder = new StringBuilder();
		builder.append(start);
		int c = 0;
		for(Object o: coll) {
			c++;
			builder.append(FormatUtils.getFormat(o, precision));
			if(c < coll.size())
				builder.append(valueSeparation);
		}
		builder.append(end);
		return builder.toString();
	}
	
	
	public static String toSimpleString(Collection coll) {
		if(coll == null)
			throw new NullPointerException();
		if(coll.isEmpty())
			return EMPTY_COLLECTION;
		return String.format(getFormat(coll, 0, " ", "", ""), coll.toArray());
	}
	
	public static String toString(Collection coll, String valueSeparation, String start, String end) {
		if(coll == null)
			throw new NullPointerException();
		if(coll.isEmpty())
			return EMPTY_COLLECTION;
		return String.format(getFormat(coll, 0, valueSeparation, start, end), coll.toArray());
	}
	
	public static  void print(Collection coll){
		if(coll == null)
			throw new NullPointerException();
		if(coll.isEmpty())
			return;
		for(T t: coll){
			System.out.println(t);
		}
	}
	
	
	/**
	 * Checks if the given list is trivial.

	 * A list is considered trivial if all its elements are equal (according to T.equals()).
	 * @param coll Basic list for operation.
	 * @return true if this list is trivial;

	 * false otherwise.
	 */
	public static  boolean isTrivial(Collection coll){
		if(coll == null)
			throw new NullPointerException();
		if(coll.isEmpty() || coll.size()==1)
			return true;
		Iterator iterator = coll.iterator();
		T firstElement = iterator.next();
		while(iterator.hasNext()){
			if(!firstElement.equals(iterator.next()))
				return false;
		}
		return true;
	}
	
	public static  boolean containSameElements(Collection> collections){
		if(collections.isEmpty() || collections.size()<2)
			return false;
		Iterator> iterator = collections.iterator();
		Collection basicSet = iterator.next();
		Collection actualSet;
		while(iterator.hasNext()){
			actualSet = iterator.next();
			if(actualSet.size() != basicSet.size())
				return false;
			if(!actualSet.containsAll(basicSet))
				return false;
		}
		return true;
	}
	
	public static  boolean containSameElements(Collection... sets){
		if(sets.length == 0 || sets.length<2)
			return false;
		Collection basicSet = sets[0];
		for(int i=1; i> C copy(C coll) 
			throws 	InstantiationException, 
					IllegalAccessException, 
					InvocationTargetException, 
					NoSuchMethodException {
		C copy = GenericReflection.newInstance(coll);
		copy.addAll(coll);
		return copy;
	}
	
	public static  T[] toArray(Collection coll, T[] a){
		if(a.length < coll.size())
			a = GenericReflection.newArray(a, coll.size());
		int i=0;
		for(T x: coll){
			a[i++]= x;
		}
		if(i < a.length)
			a[i] = null;
		return a;
	}
	
}