Question

Styles 6 2. Modify the "LinkedStackOfStrings java" program given in the textbook (program 4.3.2) by adding a method "find0 that takes a string as an argument. It should return true if the string argument is in the linked stack and false otherwise. [Mo6.1] The main method should also be modified so that all the strings (other than the search string) inputted by the user are stored on the stack before calling the find0 method. Sample runs would be as follows. . >java LinkedStack○Strings hello this is a test run for the hello program <CTRL-D hello exists in the linked stack java LinkedStackOfStrings winter hello world is the first program of any programming language <CTRL-D> winter does not exist in the linked stack (Ctrl)

Answer 1

import java.util.Scanner;

public class LinkedStackOfStrings {

    private Node first;

    private class Node {
        private String item;
        private Node next;
    }

    public boolean isEmpty() {
        return first == null;
    }

    public void push(String item) {
        Node oldFirst = first;
        first = new Node();
        first.item = item;
        first.next = oldFirst;
    }

    public String pop() {
        String item = first.item;
        first = first.next;
        return item;
    }

    public boolean find(String item) {
        Node temp = first;
        while (temp != null) {
            if(temp.item.equals(item)) return true;
            temp = temp.next;
        }
        return false;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = args[0];
        LinkedStackOfStrings list = new LinkedStackOfStrings();
        while(in.hasNextLine()) {
            list.push(in.nextLine());
        }
        if(list.find(str)) {
            System.out.println(str + " exists in the linked stack");
        } else {
            System.out.println(str + " does not exist in the linked stack");
        }
    }

}