Array Tools

• Arrays Class
  • Sorting of Arrays
  • Binary Search for already sorted array
  • Equals check of an array (.equals overridden method is called)
  • parallelPrefix() – All all the numbers consecutively
  • fill() – Assigns a default value to the complete array
  • copyOf() – Copies one array to another
  • asList – Converts arrays to list
  • hashcode – returns the hashcode
• ArrayUtils (Pending Examples)
  • add() – Used to add two arrays
  • insert() – at a specific index
  • clone
  • contains
  • get – safe from index out of bound exception
  • indexOf – find index of an elemenet
  • isEmpty
  • isNotEmpty
  • isSameLength
  • isSorted
  • lastIndexOf
  • nullToEmpty – null reference of array is converted to empty array
  • remove – Remove element at index passed – All subsequent elements are shifted to the left 
  • removeElement – removes element passed- All subsequent elements are shifted to the left 
  • removeAll
  • removeAllOccurance

Array Class Example :

package com.demo.collections;

import java.awt.Point;
import java.util.Arrays;

public class ArrayDemo {
	public static void main(String[] args) {
		int[] numberArray = new int[] {54,11,23,88,39,10,51,14,77,30,91,10,53};
		int[] unicode= new int[] {'V','b','D','p','O','K','A'};
		String[] stringArray = new String[] {"xzy","xyz","pqr","abc","acb","xab","abc"};

		
		int[] y;
		String[] z;
		
		//Sorting
		System.out.println("Original Number Array : "+Arrays.toString(numberArray));
		
		y = Arrays.copyOf(numberArray,numberArray.length); //copy an array
		Arrays.sort(y);//sort an Array
		System.out.println("Completely Sorted : "+Arrays.toString(y));
		
		y = Arrays.copyOf(numberArray,numberArray.length);
		Arrays.sort(y,0,5);//sort 0 to 5
		System.out.println("First 5 sorted : "+Arrays.toString(y));
		
		
		System.out.println("Original String Array : "+Arrays.toString(stringArray));
		
		z = Arrays.copyOf(stringArray,stringArray.length);
		Arrays.sort(z);
		System.out.println("Completely Sorted : "+Arrays.toString(z));
		
		Point[] points =  {new Point(1,2), new Point(2,3), new Point(1,1)};
//		Arrays.sort(points); //java.awt.Point cannot be cast to java.lang.Comparable, since comparable interface is required
				
		
		//Binary Search the array should be in sorted order
		y = Arrays.copyOf(numberArray,numberArray.length);
		Arrays.sort(y);
		System.out.println(Arrays.binarySearch(y,50));//-8 since at 8th location itshould have been present but it is not
		System.out.println(Arrays.binarySearch(stringArray,"abc"));
		
		
		//equals
		y = Arrays.copyOf(numberArray,numberArray.length);
		System.out.println(Arrays.equals(y,numberArray));//true
		Arrays.sort(y);
		System.out.println(Arrays.equals(y,numberArray));//false
		z = Arrays.copyOf(stringArray,stringArray.length);
		System.out.println(Arrays.equals(z,stringArray));//true
		Arrays.sort(z);
		System.out.println(Arrays.equals(z,stringArray));//false
		
	}
}