Thread: Searching for string values in a circular list

Hello Everyone,

1st and foremost I would like to greet all forum members. I am having a nightmare trying to set this program to search for string values with-in a circular list. My objective here is to input a value corresponding to a surname of class person which extends from another class called AnyClass. The result should be found or not found in list ( the surname)and a display of the record. I have already sorted out the index number search and would be ETERNALLY GRATEFULL for anybody who sorts me out in this regard.(the surname part). here under is the code. if anybody wants to paste it to an editor to test, i have grouped all classes in 1 , But the utilities file is separate.

import java.util.*;
 
class Utilities
{
	public static String randName( int n)
		{ String name = "";   // empty string
		  name = name + (char)randInt(65,90);
		  for (int k = 1; k < n; k++)
		    name = name + (char)randInt(97,122);
 		 return name;
	 	}
}
 
 
 import java.util.*;
 import java.io.*;
 
 
 
 
 class Node
 
 
{  	public Node next;
	public Person obj;
 
	public Node( Person newObj)
	   {   obj = newObj;
		   next = null;
	   }
 
	public void show()
		{ System.out.println(obj.getData());
		}
 
	public void editNode()
		{ //obj.editData();
		}
}
 
 
 
 class AnyClass
 
// Refer to T1
{
  int seqNo;
 
	/* ------------ Constructor (random data) ------------------*/
 
   public AnyClass( int num)
   { seqNo = num;
	}
 
	public AnyClass()
	{
	}
 
	/* ------------ Methods ------------------*/
 
	public String getData()
	{ return "Sequence number: "+ seqNo +". ";
	}
 
	public void editData()
	{
	}
 
	public boolean equals (Object keyObj)
	{   AnyClass temp = (AnyClass) keyObj;
	    return (temp.seqNo == this.seqNo);
	}
 
	public boolean equals (String key)
		{	 return false;
		}
}
 
 
 class Person extends AnyClass
{
 
   private String surname;
   int id;
 
   protected double pay;
 
 
	public Person (String iSurn,int iIdNo, double iPay) {
		super (iIdNo);
		surname = iSurn;
		id = iIdNo;
		pay = iPay;
	 }
	public Person ()
	{  }
 
 
	double getSalary() // returns value of object's data - encapsulation (no direct access)
	  {
		return pay;
	  }
 
	void setPay (double newPay) //alterates  value of object's data - encapsulation (no direct access)
	  {
		 pay = newPay;
	  }
 
 public String getData()
  {
	  return super.getData()+"Surname: "+surname+", "+"ID No: "+id+ "Salary EUR "+getSalary();
  }
 
/*public boolean equals(Object keyObj)
  { Person temp = (Person)keyObj;
   return (temp.seqNo==this.seqNo);//&&(temp.surname == this.surname);
   }  // maybe wrong
*/
 
public boolean equals(String keyName)
 { return(this.surname.equals(keyName));
}
 
 
 
 
 
} // end of class Person
 
 
 
 class List    // Refer to notes
 
{  	public Node head;
 
 
       	public List()
	   	   {   head = null;
	         }
 
 
 
 
 public String getData() // create empty CLL
        {
            if(head==null)return "Empty List";  		//if last is null, print "()"
            Node temp = head.next;				// create temporary pointer and assign to last.next to start from beginning
            String retval = "( ";				// print "(" to indicate start of CLL  print
 
                do
                {
                  temp.show();
                  retval= (retval + temp.obj.getData() + " ");  // print "(" + object data
                  temp = temp.next;								// incriment temp to next node
                }
                while(temp!=head.next);			// do this until temp has reach again the first node
                retval+=")";						// when first node is reached, print ")"
            return "End of Process";						// return all available data
        }
 
 
 
 public boolean isEmpty()
        {
			return (head==null);
		}
 
 
		public void clear()
        {
			head=null;
		}
 
  public Object delete()
         {
             if(isEmpty())return ("empty list");
                Object temp = head.next.obj;  //obj
 
             head.next = head.next.next;
             return temp;
         }
 
 
        public AnyClass equals(AnyClass keyObj)     // ()
         {
             if(isEmpty())System.out.println("is Empty");
             Node temp = head.next;
 
                   do
                   {
                     if(temp.obj.equals (keyObj)) //System.out.println("Found");
                     return temp.obj;
                     temp=temp.next;
 
                    }
                   while(temp!=head.next);
                   return null;
          }
 
          public Person equals(Person keyObj)     // ()
		           {
		               if(isEmpty())System.out.println("is Empty");
		               Node temp = head.next;
 
		                     do
		                     {
		                       if(temp.obj.equals (keyObj)) //System.out.println("Found");
		                       return temp.obj;
		                       temp=temp.next;
 
		                      }
		                     while(temp!=head.next);
		                     return null;
          }
 
 
 public void reverse()
          {
              List temp = new List();
              Node temper = head.next;
              if(isEmpty()){}
              else
                 {
                   do{
                       temp.append(temper.obj);
                       temper = temper.next;
                       }
                   while(temper!=head.next);
                        head = temp.head;
                  }
          }
 
 
	public void append(Person newObj)
       {
		   Node temp = new Node(newObj);   //newObj
 
           if(head ==null)
             {
              temp.next = temp;
              head = temp;
             }
           else
             {
              temp.next = head.next;
              head.next = temp;
             }
         }
 
 
}
 
 
 
public class mainList
{
 
 public static void main(String [] args)
 {
 
 
List myList = new List();   // empty list
 
		myList.getData();
 
     	for (int k = 1; k<= 10; k++)
	    myList.append(new Person(Utilities.randName(6),k,600.00));
 
		myList.getData();
 
 
		System.out.println("\n");
 
 
		System.out.println("************** Circular list Search Function*********************");
		System.out.println("\n");
 
		Scanner myInp = new Scanner(System.in);
		System.out.println("Please enter value to search?");
        int i = myInp.nextInt();
 
		AnyClass key = new AnyClass(i);
		AnyClass temp = myList.equals(key);
 
         if( temp!= null)
                System.out.println("Object found. Its data is: "+temp.getData());
 
           else
                 System.out.println("Object Not Found!");
 
 
    System.out.println("************** Circular list Search Function 2*********************");
		System.out.println("\n");
 
 
String nameInput;
 
 
Scanner in = new Scanner(System.in);
System.out.println("Enter name to search; ");
nameInput = in.nextLine();
 
 
 
	}
}

When posting code, please use highlight tags to preserve formatting. I added them for you this time.

Also, that's way too much code for us to go through. We just don't have time. For better help sooner, create an SSCCE that demonstrates what you've tried and where you're stuck.

So, where are you stuck exactly?

Still, I'm not sure where the problem is. You say you're having trouble with the equals() method? What exactly is giving you trouble?

Interesting. Usually equals() methods return a boolean. Your method looks more like a get() or a find() function.

Yeah I understand how you're using the method, it's just a little misleading because equals() is a very specific method in the Object class, and it is overridden for a different purpose. It's fine as long as it works, but I would have called the method something else. To each their own.

Hmm, I'm not sure without an SSCCE. What happens instead of what you'd expect?