The PriorityQueue and TreeSet collection classes has a lot of similarities e.g. both provide O(log(N)) time complexity for adding, removing, and searching elements, both are non-synchronized and you can get element from both PriorityQueue and TreeSet in sorted order, but there is fundamental difference between them, TreeSet is a Set and doesn't allow a duplicate element, while PriorityQueue is a queue and doesn't have such restriction. It can contain multiple elements with equal values and in that case head of the queue will be arbitrarily chosen from them. Another key difference between TreeSet and PriorityQueue is iteration order, though you can access elements from the head in a sorted order e.g. head always give you lowest or highest priority element depending upon your Comparable or Comparator implementation but iterator returned by PriorityQueue doesn't provide any ordering guarantee.
In Hibernate framework, an entity can be in three states, transient, persistent, and detached. When an object is in transient state, it is commonly refereed as transient object, similarly if it is in persistence and detached state, it is known as persistent and detached object. When an entity is first created using the new operator e.g. new User() and not associated with Hibernate session e.g. you haven't called session.save(user) method then it is known as transient object. At this stage, Hibernate doesn't know anything about this object and the object doesn't have any representation in database e.g. a corresponding row in the User table. Hibernate will not run any SQL query to reflect any changes on this object. You can move this object into persistent state by associating it with an hibernate session e.g. by calling save() or saveOrUpdate() method from an hibernate Session.
What is the difference between
@Autowired and @Inject annotation in Spring is one of the frequently asked questions on Spring interviews? Since everybody is now moved or moving to annotation driven, Java configuration in Spring, this question has become even more important for prospective candidates looking for a Java web development job using Spring framework. The @Autowired annotation is used for auto-wiring in Spring framework. The Autowiring is a process on which Spring framework figure out dependencies of a Spring bean, instead of you, a developer, explicitly specifying them in the application context file. You can annotate fields and constructor using @Autowired to tell Spring framework to find dependencies for you.
Though all three, CAST, CONVERT and PARSE are used to convert one data type into another in SQL Server, there are some subtle differences between them.The CAST method accepts just two parameters, expression, and target type, but CONVERT() also takes a third parameter representing the format of conversion, which is supported for some conversions, like between character strings and date time values. For example, CONVERT(DATE, '2/7/2015', 101) converts the character string '2/7/2015' to DATE using DATE format 101, representing United States standard. By using the PARSE function, you can also indicate the culture by using any culture supported by the Microsoft's dot NET framework. For example, PARSE('7/8/2015' AS DATE USING 'en-US') parse the input literal as a DATE by using a United State English Culture, similar to 101 formatting style.
What is the difference between revalidate() and repaint() in Java Swing is one of the popular Swing Interview Questions especially on Investment banks? Though both methods sound similar, there is a subtle difference between them. the revalidate() method instruct LayoutManager to recalculate layout and often called once new components are added or removed from Container. The revalidate() can also trigger to call to the repaint() method to repaint components which have changed i.e. width, height or any other visible property, which can affect layout. On the other hand repaint() method puts a paint request in AWT thread, for repainting of a component on which it has called.