ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

What is difference between Set and List interface in Java - Collection

Updated on August 17, 2012

List and Set in Java

What is difference between List and Set Collection class in Java and When do you use List and Set collection is one of the frequently asked but tricky Java interview question, especially the usage part. In order to know where to use List collection and where to use Set collection, Its important to understand difference between List and Set in Java. Both List and Set Collection classes are derived from java.util.Collection interface and all the operations which are applicable for Collection interface is applicable to List and Set in Java like add() , addAll(), remove() and removeAll(). In this Java tutorial we will see What are main differences between Set and List interfaces and Where to use Set interface and where to use List interface in Java.


Set vs List interface in Java

here are list of differences between Set and List interface in Java, All these differences are also applicable to various implementation of List and Set interface as well like Difference between ArrayList and HashSet, Difference between LinkedList and HashSet in Java etc.

1) One of the fundamental difference between List and Set interface is that, List interface allows duplicates objects stored in List while Set does not allow duplicates. Set implementation classes like HashSet, TreeSet will always contain Unique elements. for example if you create a Set of String like Set<String> and stored "abcd" on it then you can not another String "abcd" on this Set but you can do same with any List implementation like ArrayList or LinkedList in Java.

2) Another important difference between List and Set interface is that, List is an ordered collection while Set is an unordered collection. This is a very useful feature if you want to maintain orders like FIFO(First In First Out) etc. What this means is that if we store two objects A and B in any List implementation like ArrayList, Vector and LinkedList they will be stored in the ordered they are inserted i.e. first element in the List would be A and second element in the List would be B and you can retrieve them by calling get(0) and get(1), Also when you iterate over List they will be processed in same order. On the other hand Set interface doesn't maintain any Order and any Set implementation like HashSet will not guarantee on which order elements will be stored. On the other hand SortedSet like TreeSet guarantees particular sorting order based upon which comparator or comparable are used, but they don't maintain insertion order.

These were some of the main differences between List and Set interface in Java and by knowing these differences you can decide where to use List collection and where to use Set collection in Java. In summary use List collection like ArrayList, LinkedList if you have duplicates to store and want to maintain order while use Set collection like HashSet if you want to store only unique elements in the Set without any order guarantee.

Some of the other Interview article you may like

Difference between String and StringBuffer in Java

Advanced Java concurrency Interview questions for Senior developers

What is CLASSPATH and PATH in Java

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)