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Collection Utils
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‎README.md

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- [X] [StringUtils](../master/src/com/deepak/data/structures/Utils/StringUtils.java)
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- [X] [NumberUtils](../master/src/com/deepak/data/structures/Utils/NumberUtils.java)
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- [X] [ArrayUtils](../master/src/com/deepak/data/structures/Utils/ArrayUtils.java)
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- [ ] ListUtils
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- [X] [BooleanUtils](../master/src/com/deepak/data/structures/Utils/BooleanUtils.java)
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- [ ] CollectionUtils
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- [X] [MapUtils](../master/src/com/deepak/data/structures/Utils/MapUtils.java)
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- [ ] DateUtils
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**18. Iterators**
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- [X] [Standard Iterator](../master/src/com/deepak/data/structures/Iterators/StandardIterator.java)

‎src/com/deepak/data/structures/Utils/CollectionUtils.java

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/**
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* Data-Structures-In-Java
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* CollectionUtils.java
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*/
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package com.deepak.data.structures.Utils;
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import java.util.ArrayList;
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import java.util.Comparator;
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import java.util.List;
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import java.util.Random;
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/**
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* Utilities for collections i.e List
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*
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* @author Deepak
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*/
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public class CollectionUtils {
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/**
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* Method to check if list is empty
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*
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* @param list
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* @return {@link boolean}
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*/
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public static <T> boolean isEmpty(List<T> list) {
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return list == null || list.size() == 0;
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}
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/**
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* Method to sort the list with no comparator
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*
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* @param list
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* @return {@link List<T>}
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*/
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public static <T> List<T> sort(List<T> list) {
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list.sort(null);
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return list;
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}
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/**
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* Method to sort the list with custom comparator
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*
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* @param list
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* @param comparator
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* @return {@link List<T>}
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*/
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public static <T> List<T> sort(List<T> list, Comparator<T> comparator) {
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list.sort(comparator);
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return list;
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}
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/**
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* Method to perform a binary search
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*
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* @param list
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* @param element
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* @param comparator
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* @return {@link T}
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*/
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public static <T> T binarySearch(List<T> list, T element, Comparator<T> comparator) {
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if (list.isEmpty()) {
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return null;
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}
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int low = 0;
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int high = list.size() - 1;
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while (high > low) {
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int mid = (low + high) / 2;
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if (list.get(mid) == element) {
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return element;
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} else if (comparator.compare(list.get(mid), element) > 0) {
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high = mid - 1;
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} else {
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low = mid + 1;
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}
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}
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return null;
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}
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/**
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* Method to reverse the list
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*
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* @param list
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* @return {@link List<T>}
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*/
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public static <T> List<T> reverse(List<T> list) {
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if (list != null && list.size() > 0) {
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List<T> updatedList = new ArrayList<>();
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for (int i = list.size() - 1; i >= 0; i--) {
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updatedList.add(list.get(i));
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}
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return updatedList;
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}
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return null;
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}
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/**
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* Method to shuffle the list
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*
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* @param list
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* @return {@link List<T>}
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*/
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public static <T> List<T> shuffle(List<T> list) {
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if (list != null && list.size() > 0) {
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List<T> updatedList = new ArrayList<>();
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final int[] ints = new Random().ints(0, list.size()).distinct().limit(list.size()).toArray();
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for (int i = 0; i < ints.length; i++) {
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updatedList.add(list.get(i));
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}
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return updatedList;
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}
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return null;
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}
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/**
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* Method to swap elements at two indexes
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*
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* @param list
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* @param minIndex
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* @param maxIndex
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* @return {@link List<T>}
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*/
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public static <T> List<T> swap(List<T> list, int minIndex, int maxIndex) {
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if (list != null && list.size() > 2 && maxIndex > minIndex) {
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T elementAtMinIndex = list.get(minIndex);
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T elementAtMaxIndex = list.get(maxIndex);
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list.add(minIndex, elementAtMaxIndex);
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list.add(maxIndex, elementAtMinIndex);
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return list;
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}
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return null;
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}
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/**
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* Method to fill the list with the given element
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*
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* @param list
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* @param element
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* @return {@link List<T>}
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*/
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public static <T> List<T> fill(List<T> list, T element) {
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if (list != null && list.size() > 0) {
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for (int i = 0; i < list.size(); i++) {
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list.add(i, element);
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}
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return list;
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}
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return null;
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}
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/**
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* Method to find the minimum from the list
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*
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* @param list
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* @param comparator
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* @return {@link T}
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*/
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public static <T> T min(List<T> list, Comparator<T> comparator) {
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return null;
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}
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public static <T> T max(List<T> list, Comparator<T> comparator) {
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return null;
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}
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public static <T> List<T> rotate(List<T> list, int n) {
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return null;
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}
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}

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