Question

Exercise 1

Modify the List class of Figure 21.3 in the textbook to include a method that recursively searches a linked-list for a specified value. Ensure that the name of your method includes your last name. The method must return a reference to the value if it is found; otherwise, it must return null. Use your method in a test program that creates a list of integers. The program must prompt the user for a value to locate in the list.

My code... but not putting out the right output needed

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

public class ListSearch {

  

public static <T> T search(List<T> list, T value, int index){

  

if(list == null || index == list.size())

return null;

  

if(value.equals(list.get(index)))

return list.get(index);

  

return search(list, value, index+1);

  

}

  

public static void main(String[] args) {

  

List<Integer> list = new ArrayList<>();

  

System.out.println("Enter integers(-1 to stop): 4, 11, 32, 16, 77, 44, 33, 10, -1 ");

int num;
  

Scanner sc = new Scanner(System.in);

  

while(true){

num = sc.nextInt();

  

if(num == -1)

break;

list.add(num);

}

  

System.out.print("Enter integer to search: ");

int key = sc.nextInt();

  

Integer res = search(list, key, 0);

  

if(res == null)

System.out.println(key+" is not in list");

else

System.out.println(key+" is available in list");

}

Answer 1

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Main {
public static <T> T search_mylastname(List<T> list, T value, int index){//function name can be updated in all places to the lastname if needed
  
if(list == null || index == list.size())
return null;
  
if(value.equals(list.get(index)))
return list.get(index);
  
return search_mylastname(list, value, index+1);
  
}
  
public static void main(String[] args) {
  
List<Integer> list = new ArrayList<>();
  
System.out.println("Enter integers(-1 to stop): ");
int num;
Scanner sc = new Scanner(System.in);
while(true){
num = sc.nextInt();
if(num == -1)
break;
list.add(num);
}
  
System.out.print("Enter integer to search: ");
int key = sc.nextInt();
Integer res = search_mylastname(list, key, 0);
if(res == null)
System.out.println(key+" is not in list");
else
System.out.println(key+" is available in list");
}
}

Screenshots:

The screenshots are attached below for reference.

Please follow them for output.

The errors in the given code are modified and the output is obtained as shown below.