Your question: How do you delete a list in Java?

How do you clear a list in Java?

ArrayList. clear() method removes all of the elements from this list. The list will be empty after this call returns.

What does list Remove do in Java?

Removes the first occurrence of the specified element from given list, if the element is present. If the element is not present, the given list is not changed. After removing, it shifts subsequent elements(if any) to left and decreases their indexes by 1.

How do you remove one list from another in Java?

How to remove a SubList from a List in Java

  1. Method 1: Using subList() and clear() method. Syntax: List.subList(int fromIndex, int toIndex).clear() Example: …
  2. Method 2: Using removeRange() method. Syntax: List.removeRange(int fromIndex, int toIndex) Example: // Java code to remove a subList.

How do you check if an ArrayList is empty?

To check if an ArrayList is empty, you can use ArrayList. isEmpty() method or first check if the ArrayList is null, and if not null, check its size using ArrayList. size() method. The size of an empty ArrayList is zero.

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How do you clear an ArrayList?

There are two ways to empty an ArrayList – By using ArrayList. clear() method or with the help of ArrayList. removeAll() method.

How do I remove duplicates from a list?

Approach:

  1. Get the ArrayList with duplicate values.
  2. Create a LinkedHashSet from this ArrayList. This will remove the duplicates.
  3. Convert this LinkedHashSet back to Arraylist.
  4. The second ArrayList contains the elements with duplicates removed.

How do I remove a value from a list?

Use del to remove an element by index, pop() to remove it by index if you need the returned value, and remove() to delete an element by value.

How do you remove the last element of an ArrayList?

We can use the remove() method of ArrayList container in Java to remove the last element. ArrayList provides two overloaded remove() method: remove(int index) : Accept index of the object to be removed. We can pass the last elements index to the remove() method to delete the last element.

What does ArrayList remove do?

remove(int index) method removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices).

What is size () in Java?

The size() method of the List interface in Java is used to get the number of elements in this list. That is, this method returns the count of elements present in this list container. … Return Value: This method returns the number of elements in this list.

Can we remove elements from ArrayList while iterating?

ArrayList provides the remove() methods, like remove (int index) and remove (Object element), you cannot use them to remove items while iterating over ArrayList in Java because they will throw ConcurrentModificationException if called during iteration.

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How do I remove an object from a list in Java?

The remove(Object obj) method of List interface in Java is used to remove the first occurrence of the specified element obj from this List if it is present in the List. Parameters: It accepts a single parameter obj of List type which represents the element to be removed from the given List.

How do you remove all occurrences of a number from a list in Java?

Given an array and a key, the task is to remove all occurrences of the specified key from the array in Java.

Using List. removeAll():

  1. First Create an empty List of Array.
  2. Insert all elements of the array into the list.
  3. Remove all element which is you want to remove.
  4. Convert the list back to an array and return its.

How do you remove multiple items from an ArrayList in Java?

2. Examples

  1. Remove multiple objects using List. removeAll method. If both are collection objects and we want to remove all element from another collection then removeAll can be used. …
  2. Remove multiple objects using List. removeIf (Java 8) …
  3. Remove multiple objects using Iterator (Java 7) Remove elements using Iterator.
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