Write a method called switchPairs that switches the order of values in the list in a pairwise fashion. Your method should switch the order of the first two values, then switch the order of the next two, switch the order of the next two, and so on. If the list contains an odd number of values, the final element is not moved. For example, if the list initially stores [10, 25, 31, 47, 52, 68, 77], your method should switch the first pair (10 and 25), the second pair (31 and 47), and the third pair (52 and 68) to yield [25, 10, 47, 31, 68, 52, 77].

PLEASE ALSO CREATE A TEST CLIENT TO TEST OUT THE PROGRAM.

Provided Files:

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LinkedIntList.java

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// Class LinkedIntList can be used to store a list of integers.

public class LinkedIntList implements IntList { private ListNode front; // first value in the list

// post: constructs an empty list public LinkedIntList() { front = null; }

// post: returns the current number of elements in the list public int size() { int count = 0; ListNode current = front; while (current != null) { current = current.next; count++; } return count; }

// pre : 0 <= index < size() // post: returns the integer at the given index in the list public int get(int index) { return nodeAt(index).data; }

// post: creates a comma-separated, bracketed version of the list public String toString() { if (front == null) { return "[]"; } else { String result = "[" + front.data; ListNode current = front.next; while (current != null) { result += ", " + current.data; current = current.next; } result += "]"; return result; } }

// post : returns the position of the first occurrence of the given // value (-1 if not found) public int indexOf(int value) { int index = 0; ListNode current = front; while (current != null) { if (current.data == value) { return index; } index++; current = current.next; } return -1; }

// post: appends the given value to the end of the list public void add(int value) { if (front == null) { front = new ListNode(value); } else { ListNode current = front; while (current.next != null) { current = current.next; } current.next = new ListNode(value); } }

// pre: 0 <= index <= size() // post: inserts the given value at the given index public void add(int index, int value) { if (index == 0) { front = new ListNode(value, front); } else { ListNode current = nodeAt(index - 1); current.next = new ListNode(value, current.next); } }

// pre : 0 <= index < size() // post: removes value at the given index public void remove(int index) { if (index == 0) { front = front.next; } else { ListNode current = nodeAt(index - 1); current.next = current.next.next; } }

// pre : 0 <= i < size() // post: returns a reference to the node at the given index private ListNode nodeAt(int index) { ListNode current = front; for (int i = 0; i < index; i++) { current = current.next; } return current; }

}

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IntList.java

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/* This is the interface definition for the IntList data type */ public interface IntList { public int size(); public int get(int index); public String toString(); public int indexOf(int value); public void add(int value); public void add(int index, int value); public void remove(int index); }

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ListNode.java

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// ListNode is a class for storing a single node of a linked // list. This node class is for a list of integer values.

public class ListNode { public int data; // data stored in this node public ListNode next; // link to next node in the list

// post: constructs a node with given data and given link public ListNode(int data, ListNode next) { this.data = data; this.next = next; }

// post: constructs a node with given data and null link public ListNode(int data) { this(data, null); }

// post: constructs a node with data 0 and null link public ListNode() { this(0, null); } }