Question

Exercise 1

Modify the List<T> 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.

I need the code modified in java to pull out the correct input below is my code, but when ran the only out I get is "Enter integers(-1 to stop):" and nothing else

PLEASE HELP

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): "
       + "2, "
       + "4, "
       + "6, "
       + "8, "
       + "10");
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");
}
}

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): "
+ "2, "
+ "4, "
+ "6, "
+ "8, "
+ "10");
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");
}
}

Output:

The output when the above code is run is attached below.

Please check it.

Explanation:

When vthe program is run, the output displayed is "Enter integers(-1 to stop):2,4,6,8,10"

Then the input numbers must be entered.

The numbers entered are as follows.

2

4

6

8

10

-1

When -1 is entered, the statement "Enter integer to search: " is displayed.

Then the number 5 is entered by us.

As 5 is not in the numbers provided, it displays the result as "5 is not in list."