In JAVA Language

Add the following methods to the LinkedCollection class, and create a test driver for each to show that they work correctly. Code each of these methods by accessing the internal variables of the LinkedCollection, not by calling the previously defined methods of the class.

String toString() creates and returns a string that correctly represents the current collection. Such a method could prove useful for testing and debugging the class and for testing and debugging applications that use the class. Assume each stored element already provides its own reasonable toString method.

int count(T target) returns a count of the number of elements e in the collection such that e.equals(target) is true.

void removeAll(T target) removes all elements e from the collection such that e.equals(target) is true.

LinkedCollection combine(LinkedCollection other) creates and returns a new SortedArrayCollection object that is a combination of this object and the argument object.

package ch05.collections;

import support.LLNode;

public class LinkedCollection implements CollectionInterface

{

protected LLNode head; // head of the linked list

protected int numElements = 0; // number of elements in this collection

// set by find method

protected boolean found; // true if target found, else false

protected LLNode location; // node containing target, if found

protected LLNode previous; // node preceding location

public LinkedCollection()

{

numElements = 0;

head = null;

}

23. public boolean add(T element) 

24. // Adds element to this collection. 

25. { 

26. LLNode newNode = new LLNode(element); 

27. newNode.setLink(head); 

28. head = newNode; 

29. numElements++; 

30. return true; 

31. } 

32. public boolean contains (T target) public T get(T target) 

33. { { 

34. find(target); find(target); 

35. return found; if (found) 

36. } return location.getInfo(); 

37. else 

38. return null; 

39. } 

Array-Based

protected void find(T target) 

{ 

 location = 0; 

 found = false; 

 while (location < numElements) 

 { 

 if (elements[location].equals(target)) 

 { 

 found = true; 

 return; 

 } 

 else 

 location++; 

 } 

} 

public boolean remove (T target) 

// Removes an element e from this collection such that e.equals(target) 

// and returns true; if no such element exists, returns false. 

{ 

 find(target); 

 if (found) 

 { 

 if (head == location) 

 head = head.getLink(); // remove first node 

 else 

 previous.setLink(location.getLink()); // remove node at location 

 numElements--; 

 } 

 return found; 

} 

Link-Based

protected void find(T target)

{

location = head;

found = false;

while (location != null)

{

if (location.getInfo().equals(target))

{

found = true;

return;

}

else

{

previous = location;

location = location.getLink();

}

}

}