Question

Make following changes. step(A)
step 1 Implementation a Generic Linked List using the program developed in the class.
step 2  Implement StackImpl class using the generic linked list.
step 3 Test the program with different type and number of matching and un-matching brackets.
This is how it works!
When you run the class MatchBrackets a popup dialog appears asking you to select a file. You are provided two input files in the project. input1.txt contains matching brackets and input2.txt does not match the brackets.
You can select any of these files to verify.

Then do steb(B)

step 1 Externalize the inner classes Node and ListIterator.
step 2 Make the appropriate changes to turn in the LinkedList class into a generic class.
step3 Use the one exception classes EmptyList where applicable.
step4 . Implement StackImpl class using the generic linked list.
step 5 Add test cases in the main method to demonstrate the working of your code.
. step 6 Run match bracket to check whether the brackets were matched or not.

Answer 1

//=======linkedList.java==================
public class linkedList<T> {
   private class node{
       public T data;
       public node next;
       public node(T data) {
           this.data=data;
           next=null;
       }
   }
   private node head;
   //__________________________
   public linkedList() {
       head=null;
   }
   //__________________________
   public boolean isEmpty() {
       return head==null;
   }
   //__________________________
   public void insertAtFront(T data) {
       node temp=new node(data);
       temp.next=head;
       head=temp;
   }
   //__________________________
   public T peek() {
       if(isEmpty())
           return null;
       return head.data;
   }
   //__________________________
   public void removeFront() {
       if(isEmpty())
           return;
       head=head.next;
   }
   //__________________________
   public String toString() {
       String result="";
       node temp=head;
       while(temp!=null) {
           result=result+temp.data+" ";
           temp=temp.next;
       }
       return result;
   }
   //__________________________
}
//=======end of linkedList.java=========
//=========StackImpl.java=============
public class StackImpl {
   private linkedList<Character> list;
   //_________________________
   public StackImpl() {
       list=new linkedList<Character>();
   }
   //________________________
   public void push(Character ch) {
       list.insertAtFront(ch);
   }
   //________________________
   public boolean isEmpty() {
       return list.isEmpty();
   }
   //________________________
   public Character top() {
       if(isEmpty())
           return null;
       return list.peek();      
   }
   //__________________________
   public void pop() {
       if(!isEmpty())
           list.removeFront();
   }
   //__________________________
   public String toString() {
       return list.toString();
   }
}
//=====end of StackImpl.java

//==========MatchBrackets.java=================
import java.util.Scanner;
import java.io.*;

public class MatchBrackets {
   //_____________________________
   public static boolean match(String expression) {
       StackImpl S=new StackImpl();
       for(int i=0;i<expression.length();i++) {
           if(expression.charAt(i)=='[')
               S.push('[');
           else if(expression.charAt(i)==']') {
               if(S.isEmpty())
                   return false;
               else if(S.top()=='[')
                   S.pop();
               else
                   return false;
           }
           else {
               return false;
           }
       }
       if(S.isEmpty()==true)
           return true;
      
       return false;
   }
   //_________main()__________________
   public static void main(String[] args) {
       try {
       String expression="";
       Scanner in=new Scanner(System.in);
       File fp;
       Scanner scr;
      
      
       System.out.println("1. input1.txt");
       System.out.println("2. input2.txt");
       System.out.print("Enter choice(1,2): ");
       int choice=in.nextInt();
      
           if(choice==1) {
               fp=new File("input1.txt");
               scr=new Scanner(fp);
               while (scr.hasNextLine()) {
                   expression=scr.nextLine();
                   System.out.println(expression+" Bracket match: "+match(expression));
               }
           }
           else if(choice==2) {
               fp=new File("input2.txt");
               scr=new Scanner(fp);
               while (scr.hasNextLine()) {
                   expression=scr.nextLine();
                   System.out.println(expression+" Bracket match: "+match(expression));
               }
              
           }else {
               System.out.println("Invalid choice!");
           }
           in.close();
       }catch(Exception e) {
           System.out.println(e);
       }
      
   }
}
//=======end of MatchBrackets.java===============
//output