What does set retainAll do?

retainAll. Retains only the elements in this set that are contained in the specified collection (optional operation). In other words, removes from this set all of its elements that are not contained in the specified collection.

What does retainAll () do in Java?

The retainAll() method of ArrayList is used to remove all the array list’s elements that are not contained in the specified collection or retains all matching elements in the current ArrayList instance that match all elements from the Collection list passed as a parameter to the method.

What is set Collection in Java?

A Set is a Collection that cannot contain duplicate elements. It models the mathematical set abstraction. The Java platform contains three general-purpose Set implementations: HashSet , TreeSet , and LinkedHashSet .

What is the use of set in Java?

Set in Java is an interface declared in java. util package. It extends the collection interface that allows creating an unordered collection or list, where duplicate values are not allowed. As the name implies, a set in Java is used to create a mathematical set.

What is Linkedlist Java?

In Java, the linked list class is an ordered collection that contains many objects of the same type. Data in a Linked List is stored in a sequence of containers. The list holds a reference to the first container and each container has a link to the next one in the sequence.

What are differences between set and list?

The main difference between List and Set is that List allows duplicates while Set doesn’t allow duplicates. List is an ordered collection it maintains the insertion order, which means upon displaying the list content it will display the elements in the same order in which they got inserted into the list.

What is difference between List and set?

List and Set interfaces are one of them that are used to group the object. The main difference between List and Set is that Set is unordered and contains different elements, whereas the list is ordered and can contain the same elements in it.

Can you give examples of classes that implement the set interface?

In order to use functionalities of the Set interface, we can use these classes: HashSet. LinkedHashSet. EnumSet.

What is LinkedList in Java with examples?

Similar to arrays in Java, LinkedList is a linear data structure. However LinkedList elements are not stored in contiguous locations like arrays, they are linked with each other using pointers. Each element of the LinkedList has the reference(address/pointer) to the next element of the LinkedList.

Does LinkedList implement list?

The LinkedList class has all of the same methods as the ArrayList class because they both implement the List interface. This means that you can add items, change items, remove items and clear the list in the same way.

How to create a set in Java?

– Get the Array to be converted. – Create the Set by passing the Array as parameter in the constructor of the Set with the help of Arrays.asList () method – Return the formed Set

How do I set up Java?

For setting up java path for your system, follow the instructions given below: First right click on “my computer” and select properties. System properties -Setting up java path. Then go to Advanced system settings and click on the “Environment Variables…” button and a new tab will open up as shown below Advanced system settings.

What is get and set method in Java?

Get and Set methods in Java Toolkits in Java. Suppose some programmer is given a certain Java Class library. That is a collection of Java Classes used as a toolkit for developing something. Getter methods. Simple solution is available for the problem. Use a getter method for the variable. Setter Methods. Use a set method for that. Yeh now it’s almost finished.

What is set and list in Java?

Duplicate Objects. The main difference between List and Set interface in Java is that List allows duplicates while Set doesn’t allow duplicates. All implementation of Set honor this contract. While a Map holds two objects per Entry e.g. a key and a value and It may contain duplicate values but keys are always unique.