Searching a Java LinkedList

Question

I am trying to search through a Java LinkedList that uses a custom object called Name. I need to search on first name (My compareTo method in Name already compares last names because I need to use it to sort by last name). Name has an observer method called getFirstName().

I am not having any success in accessing first name from my LinkedList. This is what I want to do but this (obviously) doesn't work.

if (iterator.next().getFirstName().equals(inputSearch))

Can someone point me in the right direction?

This is the full method I am currently trying to write:

// Creating a method to search for a first name
 static void searchName()
{
 Scanner inData = new Scanner(System.in);
 // Label to request input from user
 System.out.println("Enter the first name that you would like to search for:");
 // Setting variable to capture input
 String inputSearch = inData.next();
 // Creating an iterator to search through the list
 iterator = list.iterator(); 
 // While loop to search each entry
 while (iterator.hasNext())
 {
 if (iterator.next().getFirstName().equals(inputSearch))
 {
 System.out.println("MATCH FOUND: " + iterator.next());
 }
 }
} 

• Dave Newton: What specifically doesn't work? I mean, clearly calling next() twice is... sub-optimal.
• dominicvautour: "if (iterator.next().getFirstName().equals(inputSearch))" gives an error: cannot find symbol - method getFirstName()
• dominicvautour: I definitely would be open to any ...optimal... solution

Answer 1

You're calling iterator.next() twice. The second time will advance past the item you want. Instead, save the return value from the first call to iterator.next() and use that.

 while (iterator.hasNext())
 {
 Name item = (Name) iterator.next();
 if (item.getFirstName().equals(inputSearch))
 {
 System.out.println("MATCH FOUND: " + item);
 }
 }

or, more idiomatically

 for (Name item : list)
 {
 if (item.getFirstName().equals...
 }

• dominicvautour: When I try to compile the modified code I get a compiler error "incompatible types - found java.lang.Object but expected Name" on Name item = iterator.next()
• Jim Garrison: I fixed the example. Your List is not generic, and should be declared as List<Name> rather than just List. If you change the declaration to List<Name> then you can omit the cast.

Answer 2

while (iterator.hasNext()) { 
 if (iterator.next().getFirstName().equals(inputSearch)) { //iterator.next() 
 System.out.println("MATCH FOUND: " + iterator.next()); //iterator.next() 
 } 
 } 

Since you are calling next() twice, while printing it would be next object.

try storing whatever iterator.next() returns in its corresponding type and use it to compare and print if succeed.

ex:

while(iterator.hasNext(){
 Name name=iterator.next();
 if(name.getFirstName().equals(inputSearch)){
 System.out.println("Match Found"+name);
 }
}

This is what I see wrong. Not aware of anything else.