I want to use if statement for a multiple choice with string variable... However, I can't input an answer or letter of my choice and it just immediately outputs "Input Error" even though I haven't input anything yet... Can I ask what's wrong with this code?
System.out.println("Pick your choice: \na. Add Node\nb. Delete Node\nc. Insert Node");
String letterChoice = scan.nextLine();
if(letterChoice.equalsIgnoreCase("A")){
System.out.println("Enter node value: ");
int nodeValue = scan.nextInt();
list.addNodes(nodeValue);
}
else if(letterChoice.equalsIgnoreCase("B")){
System.out.println("Which node to delete? Node #: ");
int thisNode = scan.nextInt();
list.deleteNode(thisNode);
}
else if(letterChoice.equalsIgnoreCase("C")){
System.out.println("Input node number: ");
int thisNode = scan.nextInt();
int prevNode = thisNode - 1;
System.out.println("Input node value: ");
int nodeValue = scan.nextInt();
list.insertNode(nodeValue, prevNode);
}
else{
System.out.println("Input Error");
}
I couldn't find help from previous questions here unless I change my code... I don't want to, so I had to ask... Thanks...
Full Code...
import java.util.*;
public class DoublyLinkedList {
static DNode root;
static DNode temp;
static DNode current;
public void addNodes(int data){
DNode dNode = new DNode(data);
if(root==null){
root = dNode;
root.previousNode = null;
root.nextNode = null;
}else{
current = root;
while(current.nextNode!=null){
current = current.nextNode;
}
current.nextNode = dNode;
dNode.previousNode = current;
dNode.nextNode = null;
}
}
public void insertNode(int data, int after){
DNode dNode = new DNode(data);
int ithNode = 1;
current = root;
while(ithNode != after){
current = current.nextNode;
ithNode++;
}
temp = current.nextNode;
current.nextNode = dNode;
dNode.nextNode = temp;
temp.previousNode = dNode;
dNode.previousNode = current;
}
public void deleteNode(int nodeNumber){
int ithNode = 1;
current = root;
if(nodeNumber==1){
root = current.nextNode;
current.nextNode = null;
current.previousNode = null;
}else{
while(ithNode != nodeNumber){
current = current.nextNode;
ithNode++;
}
if(current.nextNode == null){
current.previousNode.nextNode = null;
current.previousNode = null;
}else{
current.previousNode.nextNode = current.nextNode;
current.nextNode.previousNode = current.previousNode;
}
}
}
public void print(){
current = root;
System.out.print("The Linked List: ");
do{
System.out.print(" " + current.data + " ");
current = current.nextNode;
}while(current!=null);
}
public void printBackwards(){
current = root;
while(current.nextNode!=null){
current = current.nextNode;
}
System.out.print("Inverse: ");
do{
System.out.print(" " + current.data + " ");
current = current.previousNode;
}while(current.previousNode!=null);
System.out.print(" " + current.data + " " );
}
public static void main(String[] args){
DoublyLinkedList list = new DoublyLinkedList();
Scanner scan = new Scanner(System.in);
String letterChoice = "";
int nodesNum;
System.out.print("Input number of nodes: ");
nodesNum = scan.nextInt();
for(int x = 1; x <= nodesNum; x++){
System.out.print("Input value of node #" + x + ": ");
int value = scan.nextInt();
list.addNodes(value);
}
list.print();
System.out.println("Pick your choice: \na. Add Node\nb. Delete Node\nc. Insert Node");
letterChoice = scan.nextLine();
if(letterChoice.equalsIgnoreCase("A.")){
System.out.println("Enter node value: ");
int nodeValue = scan.nextInt();
list.addNodes(nodeValue);
}
else if(letterChoice.equalsIgnoreCase("B.")){
System.out.println("Which node to delete? Node #: ");
int thisNode = scan.nextInt();
list.deleteNode(thisNode);
}
else if(letterChoice.equalsIgnoreCase("C.")){
System.out.println("Input node number: ");
int thisNode = scan.nextInt();
int prevNode = thisNode - 1;
System.out.println("Input node value: ");
int nodeValue = scan.nextInt();
list.insertNode(nodeValue, prevNode);
}
else{
System.out.println("Input Error");
}
list.print();
System.out.println();
list.printBackwards();
System.out.println();
System.out.println("The number of DNodes in the Linked List is " + DNode.noOfLinkedList);
}
}
class DNode {
static int noOfLinkedList = 0;
int data;
DNode previousNode;
DNode nextNode;
DNode(int data){
this.data = data;
noOfLinkedList++;
}
}
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