Java equals() 方法 - 用户定义的对象？

Question

嗨，equals 方法用于比较用户定义的对象。似乎它们是按内存位置进行比较，而不是按整数对象内的数据进行比较。在线资源说 equals() 方法按数据进行比较。我很困惑。我将附加代码，它是一个带尾的单链表实现。我感到困惑的地方是在 remove() 方法中，我会注意下面的行。谢谢

public class Node<T>
{
    private T element;
    private Node next;

    public Node() //constructor creates an empty node
    {
        this.element=null;
        this.next=null;
    }
    public Node(T element) //overloaded constructor creates a node with element to hold
    {
        this.element=element;
        this.next=null;
    }
    public Node<T> getNext()
    {
        return next;
    }
    public void setNext(Node<T> next)
    {A
        this.next=next;
    }
    public T getElement()
    {
        return this.element;
    }
    public void setElement(T element)
    {
        this.element=element;
    }
}

public abstract class LinkedList<T>
{
    protected int count;
    protected Node<T> head, tail;
    protected int modCount;

    public LinkedList() //creates an empty list
    {
        count=0;
        head=tail=null;
        modCount=0;
    }
       public T remove(T targetElement)
    {
        if(isEmpty())
            throw new EmptyCollectionException("LinkedList");

        boolean found=false;
        Node<T> previous = null;
        Node<T> tempNode=head;

        while(tempNode != null && !found)
        if(targetElement.equals(tempNode.getElement())) //here compares by data?
                found=true;
            else
            {
                previous =tempNode;
                tempNode=tempNode.getNext();
            }
            if(!found)
            {
                System.out.println("element not found ");
                return null;
            }
            if(size()==1)
            {
                head=tail=null;
            }
            else if(tempNode.equals(head))  //here is where comparison is made by memory
                head=tempNode.getNext();
            else if(tempNode.equals(tail))  //here
            {
                tail=previous;
                tail.setNext(null);
            }
            else
                previous.setNext(tempNode.getNext());

            count--;
            modCount++;
            return tempNode.getElement();
    }
    public boolean isEmpty()
    {
        return count <=0;
    }
    public int size()
    {
        return count;
    }
    @Override
    public String toString()
    {
        String str = "";
        Node<T> tempNode = head;
        while(tempNode != null)
        {
            str = str + tempNode.getElement() + " ";
            tempNode = tempNode.getNext();
        }
        return str;
    }
}

public class Main
{
    public static void main(String[] args)
    {
        LinkedUnorderedList<Integer> list = new LinkedUnorderedList<Integer>();
        list.addToRear(5);
        list.addToRear(6);
        list.addToRear(6);
        list.remove(6);
        System.out.println(list);
    }
}

public class LinkedUnorderedList<T> extends LinkedList<T>
{
    public LinkedUnorderedList()
    {
        super(); //sets up super class instance data
    }
}