*getting following error.
duplicate found
Exception in thread "main" java.lang.NullPointerException
at binarysearchtree.main(binarysearchtree.java:185)
Java Result: 1
here is my code*
public class node<T>
{
public node<T> root ;
public T data;
public node left;
public node right;
public node (T newData)
{
data = newData;
left = null;
right = null;
root=null;
}
public node ()
{
data = null;
left = null;
right = null;
}
public void setData (T newData)
{
data = newData;
}
public T getData ()
{
return data;
}
public void setLeft (node newLeft)
{
left = newLeft;
}
public node getLeft ()
{
return left;
}
public void setRight (node newRight)
{
right = newRight;
}
public node getRight ()
{
return right;
}
public node getRoot ()
{
return root;
}
public void setRoot (node newRoot)
{
root = newRoot;
}
public boolean equals (node theOther)
{
return this.data.equals (theOther.data);
}
public int compareTo (node theOther)
{
return ((Integer) (this.getData ())).compareTo ((Integer) (theOther.getData ()));
}
}
public class binarysearchtree<T> extends node<T>
{
public node root;
public binarysearchtree ()
{
root=null;
}
public boolean empty ()
{
return(root==null);
}
public boolean addOne (T newMember)
{
boolean success = true;
node<T> newNode = new node<T> (newMember);
if (empty ())
setRoot (newNode);
else
{
node p = null;
node c = getRoot ();
int compare = 0;
while (c != null)
{
compare = newNode.compareTo (c);
if (compare == 0)
{
System.out.println ("duplicate found");
success = false;
return success;
}
else
{
p = c;
if (compare > 0)
c = c.getRight ();
else
c = c.getLeft ();
}
}
if (compare > 0)
p.setRight (newNode);
else
p.setLeft (newNode);
}
return success;
}
public T delete (node key)
{
T dataInDeleted = null;
if (!empty ())
{
node p = null;
node c = getRoot ();
int compare = 0;
while (c != null)
{
compare = key.compareTo (c);
if (compare == 0)
break;
else
{
p = c;
if (compare > 0)
c = c.getRight ();
else
c = c.getLeft ();
}
}
if (c == null)
{
System.out.println ("not found");
return dataInDeleted;
}
else
{
dataInDeleted = (T) c.getData ();
node betweenPnC = null;
//2-child case, go right once then keep going left till null
node px = c;
node pc = c.getRight ();
if (pc.getLeft () != null)
{
px = pc;
pc = pc.getLeft ();
}
c.setData ((T) pc.getData ());
if (px == c)
px.setRight (pc.getRight ());
else
px.setLeft (pc.getRight ());
}
}
return dataInDeleted;
}
public void inOrder (node root)
{
if (root != null)
{
inOrder (root.getLeft ());
System.out.println (root);
inOrder (root.getRight ());
}
}
//use inorder traversal
public void traverse ()
{
node startPoint = getRoot ();
inOrder (startPoint);
}
public void setRoot (node newRoot)
{
root = newRoot;
}
public node getRoot ()
{
return root;
}
public node binarySearch (node key)
{
node found = null;
node temp = getRoot ( );
while (temp != null)
{
int x = key.compareTo (temp);
if (x == 0)
{
found = temp;
break;
}
else if (x < 0)
temp = temp.getLeft ( );
else
temp = temp.getRight ( );
}
return found;
}
public static void main(String[] args) {
binarysearchtree<Integer> tree = new binarysearchtree<Integer>();
tree.addOne(88);
tree.addOne(88);
tree.delete(new node(88));
tree.delete(new node(7));
tree.addOne(90);
tree.traverse();
System.out.println(tree);
}
}
