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Java Articles
Page 272 of 450
How to customize the Result of JPA Queries with Aggregation Functions?
Most of the time when we use JPA queries, the result obtained is mapped to an object/particular data type. But When we use aggregate function in queries, handling the result sometimes require us to customize our JPA query. Let’s understand this with help of an example (Department, Employee) − Dept.java @Entity public class Dept { @Id private Long id; private String name; @OneToMany(mappedBy = "dep") private List emp; //Getters //Setters } A department can have one or more ...
Read MoreHow does Hibernate Second Level Cache Works?
Caching helps to reduce database network call, for executing queries. First level cache is linked with a session. It is implemented implicitly. First level cache exist only till the session object is there. Once session object is terminated/closed, there will be no cache objects. Second level cache works across multiple sessions objects. It is linked with a session factory. Second level cache objects are available to all the session in a single session factory. These cache objects are terminated when that particular session factory is closed. Implementing second level caching We need to add the following dependencies in order to ...
Read MoreAnonymous object in Java
Anonymous object in Java means creating an object without any reference variable. Generally, when creating an object in Java, you need to assign a name to the object. But the anonymous object in Java allows you to create an object without any name assigned to that object. So, if you want to create only one object in a class, then the anonymous object would be a good approach. Reading this article, you will learn what an anonymous object is and how to create and use anonymous objects in Java. Let's get started! Anonymous Object in Java Anonymous means Nameless. An ...
Read MoreAnonymous object in Java
Anonymous object in Java means creating an object without any reference variable. Generally, when creating an object in Java, you need to assign a name to the object. But the anonymous object in Java allows you to create an object without any name assigned to that object. So, if you want to create only one object in a class, then the anonymous object would be a good approach. Reading this article, you will learn what an anonymous object is and how to create and use anonymous objects in Java. Let's get started! Anonymous Object in Java Anonymous means Nameless. An ...
Read MoreDifferent methods to append a single character to a string or char array in Java
Have you ever faced the situation of extending a string or char array? If you haven't yet, you might probably encounter this situation in the future. It is a common practice to append a single character to a string or char array in Java. The significant difference between a string array and a char array is that a string array is a sequence of characters, and a char array is a sequence of collection of data type char. String array runs as a single entity, whereas char array runs as a separate entity. In this blog, we will look ...
Read MoreDifference Between HashMap and TreeMap in Java
Both HashMap and TreeMap are considered to be Map classes because they both carry out the responsibilities of the Map interface. A Map is an object that stores key-value pairs, in which there is only one instance of each key but there may be multiple instances of the value. The hash table is a type of data structure that is utilised by the HashMap class. As a form of data storage, the red-black tree is utilised by the TreeMap.What is a HashMap?A HashMap uses a data structure known as the hash table in order to store the map's key-value pair. ...
Read MoreScala vs Java
Scala and Java are two of the most widely used high-level programming languages in the world of today's computer programming. Scala was developed specifically to address a number of Java's limitations. In particular, it is intended to be as condensed and terse as possible, with the goal of reducing the amount of code that the programmer is required to produce.Java and Scala have their own specialised fields and domains of application. Go through this article to find out the primary characteristics of these two high-level programming languages and how they are different from each other.What is Scala?Scala is a computer ...
Read MoreDifference between inheritance and composition in Java
In computer programming, the concept of reusable code refers to the utilisation of previously developed software in the construction of new software. Reusability of code is recognised as an essential component of productive functionality. Establishing associations between classes is one method that object-oriented programming uses to encourage this.In object-oriented programming, there are two primary ways to construct these relationships: inheritance and composition.In object-oriented programming (OOP), inheritance refers to the process through which an object can take on the properties of one or more other objects. In OOP, it is one of the most powerful concepts for establishing code reusability. When ...
Read MoreDifference between constructor and method in Java
Classes are the fundamental building blocks of Java. It is a programmable template that can be expanded upon, and it determines the form and characteristics of an item. One may say that a class is the most fundamental component of an object oriented programming language like Java. Each and every idea that will be put into action by means of a Java application must first be encased inside of a class. In object-oriented programming, the fundamental building blocks are called classes objects.Variables and methods are the building blocks of a Java class. Instance variables are the terms used to refer ...
Read MoreDifference between abstract class and interface
An abstract class can contain both abstract and non-abstract methods, whereas an Interface can have only abstract methods. Abstract classes are extended, while Interfaces are implemented. Read through this article to find out the other differences between an Abstract Class and an Interface and how they are used in real programs.What is an Abstract Class?An abstract class acts as a template that stores the methods and data members of a program. You should use an abstract class when you expect that it will inherited by different sub-classes with common methods and fields.Abstract classes may or may not contain abstract methods, ...
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