String comparison using .equals() does not work in Java.

Question

When comparing a string taken from console input to a string inside an array, it is always false unless I add .toString(). Both strings are equal and it should work without adding the .toString(). Can anyone help me figure out why?

Here I get the string I want to compare from the console:

System.out.println("\nEnter the name you wish to remove from the list.");
String name = in.nextLine();
System.out.println("\n\"" + myNameList.remove(new MyOrderedList(name)) + "\"" + " removed from the name list\n");

Here is the remove method:

public T remove(T element) {
    T result;
    int index = find(element);

    if (index == NOT_FOUND) {
        throw new ElementNotFoundException("list");
    }

    result = list[index];
    rear--;

    /** shift the appropriate elements */
    for (int scan = index; scan < rear; scan++) {
        list[scan] = list[scan+1];
    }

    list[rear] = null;
    return result;
}

Here is the find method that is were the problem is:

private int find(T target) {
    int scan = 0, result = NOT_FOUND;
    boolean found = false;

    if (!isEmpty()) {
        while (!found && scan < rear) {
            if (target.equals(list[scan])) { // Not sure why this does not work until I add the .toString()s
                found = true;
            }
            else {
                scan++;
            }
        }
    }

    if (found) {
        result = scan;
    }
    return result;
}

The if (target.equals(list[scan])) always returns false unless I change it to if (target.toString().equals(list[scan].toString()).

I am using an ArrayList to represent an array implementation of a list. The front of the list is kept at array index 0. This class is extended to create a specific kind of list if that helps. I can post all classes if needed.

Answer 1

You are only using String.equals if the first argument is a String.

String comparison using .equals() does not work java

It appears this is the thing which does work. Its T.equals() which doesn't work.

---

If you have this working, it means you have overridden toString() sensibly.

target.toString().equals(list[scan].toString()

but if this doesn't work

target.equals(list[scan])

it means you haven't overridden equals(Object) correctly.

Answer 2

If myNameList has a String generic parameter, then this will not work, because no String will equal a type of MyOrderedList.

If myNameList has a MyOrderedList generic parameter, then you will need to make sure that you define an equals() method for it.