Question: How do you update an address according to this code? Currently, I figured out up to (the bolded line) How do I update address, display
How do you update an address according to this code?
Currently, I figured out up to (the bolded line) How do I update address, display all entries and quit.
Add a name (n) Look up a name (l)
Update address (u)
Delete an entry (d)
Display all entries (a)
Quit (q) -> n
import java.util.Scanner;
public class AddressBook {
public static void main(String[] args) {
Tablea addressBook = new Tablea();
Scanner scanner = new Scanner(System.in);
String key, value;
// Insert a new entry into the address book
System.out.print("Enter a name: ");
key = scanner.nextLine();
System.out.print("Enter a address: ");
value = scanner.nextLine();
addressBook.insert(key, value);
// Lookup an entry in the address book
System.out.print("Enter a name to look up: ");
key = scanner.nextLine();
String result = addressBook.lookUp(key);
if (result != null) {
System.out.println("address: " + result);
} else {
System.out.println("name not found");
}
// Delete an entry from the address book
System.out.print("Enter a name to delete: ");
key = scanner.nextLine();
boolean deleted = addressBook.delete(key);
if (deleted) {
System.out.println("address deleted");
} else {
System.out.println("name not found");
}
}
}
public class Node {
private String key;
private String value;
private Node next;
Node() {
// add here ..
}
Node(String key, String value) {
// add here ..
this.key = key;
this.value = value;
this.next = null;
}
public String getKey() {
// add here ..
return this.key;
}
public void setKey(String key) {
// add here ..
this.key = key;
}
public String getValue() {
// add here ..
return this.value;
}
public void setValue(String value) {
// add here ..
this.value = value;
}
public Node getNext() {
// add here ..
return this.next;
}
public void setNext(Node next) {
// add here ..
this.next = next;
}
}
import java.util.Scanner;
public class Tablea {
private Node mark;
public Node getMark() {
return this.mark;
}
public void setMark(Node mark) {
this.mark = mark;
}
public boolean insert(String key, String value) {
Node newNode= new Node(key,value);
if (this.mark== null) {
this.mark = newNode;
}else {
newNode.setNext(this.mark.getNext());
this.mark.setNext(newNode);
}
return true;
}
public String lookUp(String key) {
Node current = this.mark;
while(current!=null) {
if (current.getKey().equals(key)) {
return current.getValue();
}
current = current.getNext();
}
return null;
}
public boolean delete(String key) {
Node current = this.mark;
Node prev = null;
while (current!= null) {
if (current.getKey().equals(key)) {
if (prev == null) {
this.mark = current.getNext();
}else {
prev.setNext(current.getNext());
}
return true;
}
prev = current;
current = current.getNext();
}
return false;
}
public boolean update(String key, String newValue) {
Node current = this.mark;
while (current != null) {
if (current.getKey().equals(key)) {
current.setValue(newValue);
return true;
}
current = current.getNext();
}
return false;
}
public boolean markToStart() {
if (this.mark== null) {
return false;
}
this.mark = null;
return true;
}
public boolean advanceMark() {
if (this.mark== null) {
return false;
}
this.mark = this.mark.getNext();
return true;
}
public String keyAtMark() {
if (this.mark== null) {
return null;
}
return this.mark.getKey();
}
public String valueAtMark() {
if (this.mark== null) {
return null;
}
return this.mark.getValue();
}
public int displayAll() {
Node current = this.mark;
int count = 0;
while (current != null) {
System.out.println(current.getKey()+":"+ current);
}
return count;
}
}
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