Java Removing Element from List

In summary, the code is attempting to remove an element from the back of the list using a dummy head and tail node. However, when testing the code, there is no execution and an error is encountered on the line of code where the element is removed. The code works correctly for removing the front element, but there is an issue with removing the back element. Additionally, the code contains an unnecessary empty node which may cause errors when trying to access its data.
  • #1
magnifik
360
0
i am trying to remove an element from the back of the list (i.e. the node right before the tail). i am using a dummy head and tail node. the code compiles correctly, but when i try to test it, there is no execution. below is the segment of code that i am referring to:


public Object removeBack() {
if (_size == 0) throw new NoSuchElementException();
Node node = new Node();
Node cursor = _tail._prev;
cursor._next._prev = cursor._prev;
cursor._prev._next = cursor._next; // this is the line of code giving me error
_size--;
return node._data;
}

i am not sure what is wrong with my code. it works properly when trying to removeFront, and the only change from that segment of the code is the cursor.
 
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  • #2
Hi magnifik! :smile:

Your code appears to correctly remove the last element in the list, so what do you mean that there is no execution?

Btw, you do create an unnecessary empty "node", of which you try to return the _data field, which will probably be empty.
Depending on how defined your Node class, this could even result in an exception.
 

FAQ: Java Removing Element from List

What is the purpose of removing an element from a Java list?

Removing an element from a Java list allows for more efficient memory management and organization of data. It also allows for the list to accurately reflect the current state of the data being managed.

How do I remove an element from a Java list?

To remove an element from a Java list, you can use the remove() method and specify the index of the element you want to remove. Alternatively, you can use the remove(Object o) method and specify the object itself that you want to remove from the list.

What happens if I try to remove an element that does not exist in the Java list?

If you try to remove an element that does not exist in the Java list, the remove() method will return a boolean value of false and the list will remain unchanged. The remove(Object o) method will also return a boolean value of false, but will not throw an error.

Can I remove multiple elements at once from a Java list?

Yes, you can remove multiple elements at once from a Java list by using the removeAll(Collection c) method. This method takes in a collection of objects and removes all occurrences of those objects from the list.

Is it possible to remove elements from a Java list while iterating through it?

Yes, you can remove elements from a Java list while iterating through it by using the remove() method from the iterator object. However, this should be done carefully as it can lead to errors and unexpected behavior if not done correctly.

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