Question

How do i rewrite this code only using the list below?

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.HashSet;

public class RotationCheck {
   /**
   * Rotates the elements in the specified list by the specified distance. After calling this
   * method, the element at index {@code i} will be the element previously at index
   * {@code (i - distance) % list.size()}, for all values of {@code i} between {@code 0} and
   * {@code list.size() - 1}, inclusive. (This method has no effect on the size of the list.)
   *
   * For example, suppose {@code list} comprises{@code ['t', 'a', 'n', 'k', 's']}.
   * After invoking {@code IntegerCollections.rotate(list, 1)} (or
   * {@code IntegerCollections.rotate(list, -4)}), {@code list} will comprise
   * {@code ['s', 't', 'a', 'n', 'k']}.
   *
   * To move more than one element forward, increase the absolute value of the rotation distance. To
   * move elements backward, use a positive shift distance.
   *
   * @param list the list to be rotated
   * @param distance the distance to rotate the list. There are no constraints on this value; it may
   * be zero, negative, or greater than {@code list.size()}.
   */
   public static void rotate(List<Integer> list, int distance) {
        Collections.rotate(list, -1*distance);
   }

   public static void main(String[] args) {
       //Create an arraylist
       List<Integer> list1=new ArrayList<Integer>();
       //Add values into list
       list1.add(1);
       list1.add(2);
       list1.add(3);
       list1.add(4);
       list1.add(5);
       //Display list
       System.out.println("Display before shift:");
       System.out.println(list1);
       //Forward shift
       System.out.println("Display after forward shift:");
       rotate(list1,-4);
       System.out.println(list1);
       //Backward shift
       System.out.println("Display after backward shift:");
       rotate(list1,1);
       System.out.println(list1);
   }

}

Answer 1

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.HashSet;

public class RotationCheck {
   /**
   * Rotates the elements in the specified list by the specified distance. After calling this
   * method, the element at index {@code i} will be the element previously at index
   * {@code (i - distance) % list.size()}, for all values of {@code i} between {@code 0} and
   * {@code list.size() - 1}, inclusive. (This method has no effect on the size of the list.)
   *
   * For example, suppose {@code list} comprises{@code ['t', 'a', 'n', 'k', 's']}.
   * After invoking {@code IntegerCollections.rotate(list, 1)} (or
   * {@code IntegerCollections.rotate(list, -4)}), {@code list} will comprise
   * {@code ['s', 't', 'a', 'n', 'k']}.
   *
   * To move more than one element forward, increase the absolute value of the rotation distance. To
   * move elements backward, use a positive shift distance.
   *
   * @param list the list to be rotated
   * @param distance the distance to rotate the list. There are no constraints on this value; it may
   * be zero, negative, or greater than {@code list.size()}.
   */
   public static void rotate(List<Character> list, int distance) {
        Collections.rotate(list, -1*distance);
   }

   public static void main(String[] args) {
       //Create an arraylist
       List<Character> list1=new ArrayList<Character>();
       //Add values into list
       list1.add('t');
       list1.add('a');
       list1.add('n');
       list1.add('k');
       list1.add('s');
       //Display list
       System.out.println("Display before shift:");
       System.out.println(list1);
       //Forward shift
       System.out.println("Display after forward shift:");
       rotate(list1,-1);
       System.out.println(list1);
       //Backward shift
       System.out.println("Display after backward shift:");
       rotate(list1,4);
       System.out.println(list1);
   }

}

Output: