linkedlist Node

[charliebhoy]

Hi I dont know were I have gone wrong maybe as usual its something so simple and I cant see the wood for the tree, I am having problems with the remove function , I have tried many variations but with no joy, I get an error when compiling the
Test class file, the problem area is

case 3 : screen.println("Remove element ");
element = targetElement;
list.remove(targetElement);



I hope someone can see my error and correct me pls
here is the full code below............................


import java.lang.Exception;

// Node class
class Node
{
int element;
Node next;

// Constructor
Node(int newElement, Node newNode)
{
element = newElement;
next = newNode;
}

int getElement()
{
return element;
}


Node getNext()
{
return next;
}

void display()
{
System.out.println(element);
}

void remove(int targetElement)
{
System.out.println(targetElement);
}
}


// Test class
import java.io.*;

public class IntListTest
{

static BufferedReader keyboard = new
BufferedReader(new InputStreamReader(System.in));
static PrintWriter screen = new PrintWriter(System.out, true);



public static void main(String[] args) throws IOException
{

IntList list = new IntList();
int choice,element,targetElement;

do {
screen.println("1. Add 2. Display 3.Remove 4. Quit");
screen.print("Enter choice ");
choice = new Integer(keyboard.readLine()).intValue();

switch (choice)
{
case 1 : screen.println("Enter new value ");
element = new
Integer(keyboard.readLine()).intValue();
list.add(element);
break;

case 2 : list.display();
break;


case 3 : screen.println("Remove element ");
element = targetElement;
list.remove(targetElement);

break;

case 4 : screen.println("Quitting");
break;
default: screen.println("Invalid choice");
}
} while (choice != 4);


}


}

// IntList class
public class IntList
{
Node head;

// Constructor

IntList()
{
head = new Node(0, null);
}

// Add
void add(int newElement)
{

Node newNode = new Node(newElement, null);

if (head.next == null)
head.next = newNode;
else

if (newNode.element < head.next.element)
{
newNode.next = head.next;
head.next = newNode;
}

else
{
Node probe;
for (probe = head.next;probe.next != null && newNode.element > probe.next.element;
probe = probe.next);
newNode.next = probe.next;
probe.next = newNode;
}

}

// Display
void display()
{
for (Node probe = head.next;probe != null;probe = probe.next)

probe.display();
}


//remove
void remove(int targetElement) {
Node probe, previous;
if (head.next.element == targetElement)
head.next = head.next.next;
else {
previous = head.next;
probe = head.next.next;
while (probe != null && probe.element != targetElement) {
previous = probe;
probe = probe.next;
}
if (probe != null)
previous.next = probe.next;
}
}

}

[floaty]

The local variable may not have been initialized. You have to set the value of targetElement, e.g. targetElement =null;

floaty

[charliebhoy]

Hi floaty
txs 4 your help, got it working now
here is the sorted part

case 3 : screen.println("Enter Value to Remove");

element = new Integer (keyboard.readLine()).intValue();
list.remove(element);

break;

[charliebhoy]

Hi again,
I have updated the program to a doubly linked list
but were printing backwords it only prints first char (last char as its going backwards)
does anyone have any idea whats up ?
below are the 3 files................................


// Test class
import java.io.*;

public class IntListTest
{

static BufferedReader keyboard = new
BufferedReader(new InputStreamReader(System.in));
static PrintWriter screen = new PrintWriter(System.out,true);



public static void main(String[] args) throws IOException
{

IntList list = new IntList();
int choice,element;


do {
screen.println();
screen.println();
screen.println( "1. Add 2. Display 3.Reverse 4.Remove 5.Quit");
screen.print( "Enter choice ");
choice = new Integer(keyboard.readLine()).intValue();
switch (choice)
{
case 1 : screen.println("Enter new value ");
element = new
Integer(keyboard.readLine()).intValue();
list.add(element);
break;

case 2 : list.display();
break;

case 3 : list.displayR();
break;

case 4: screen.println("Enter Value to Remove");
element = new Integer(keyboard.readLine()).intValue();

list.remove(element);
break;

case 5 : screen.println("Quitting");
break;
default: screen.println("Invalid choice");
}
} while (choice != 4);
}
}


// Test class
import java.io.*;

public class IntListTest
{

static BufferedReader keyboard = new
BufferedReader(new InputStreamReader(System.in));
static PrintWriter screen = new PrintWriter(System.out,true);
public static void main(String[] args) throws IOException
{

IntList list = new IntList();
int choice,element;


do {
screen.println();
screen.println();
screen.println( "1. Add 2. Display 3.Reverse 4.Remove 5.Quit");
screen.print( "Enter choice ");
choice = new Integer(keyboard.readLine()).intValue();
switch (choice)
{
case 1 : screen.println("Enter new value ");
element = new
Integer(keyboard.readLine()).intValue();
list.add(element);
break;

case 2 : list.display();
break;

case 3 : list.displayR();
break;

case 4: screen.println("Enter Value to Remove");
element = new Integer(keyboard.readLine()).intValue();

list.remove(element);
break;

case 5 : screen.println("Quitting");
break;
default: screen.println("Invalid choice");
}
} while (choice != 4);
}
}



// IntList class
public class IntList
{
Node head,tail,current;

// Constructor
IntList()
{
head = new Node(0, null);
tail= new Node(0,null);
}

// Add
void add(int newElement)
{

Node newNode = new Node(newElement, null);

if (head.next == null)
{
head.next = newNode;
tail.previous = newNode;
} else {

if (newNode.element < head.next.element)
{
newNode.next = head.next;
head.next = newNode;
tail.previous=newNode;
} else {
Node probe;
for (probe = head.next;probe.next != null && newNode.element > probe.next.element;
probe = probe.next);
newNode.next = probe.next;
probe.next = newNode;
tail.previous=newNode;
}
}
}

// Display
void display()
{
for (Node probe = head.next; probe != null; probe = probe.next)

probe.display();
}

// Display reverse
void displayR()
{
for (Node probe = tail.previous; probe != null; probe = probe.previous)
probe.display();
}
//remove
void remove(int targetElement) {
Node probe,previous;
if (head.next.element == targetElement)
head.next = head.next.next;
else {
previous = head.next;
probe = head.next.next;
while (probe != null && probe.element != targetElement) {
previous = probe;
probe = probe.next;
}
if (probe != null)
previous.next = probe.next;
}
}
}