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Java Articles
Page 129 of 450
Difference between HashTable and ConcurrentHashMap in Java
In this article, we will learn about the ConcurrentHashMap and HashTable in Java. First, we will know about ConcurrentHashMap, the syntax of ConcurrentHashMap, and an example after that will learn about HashTable, the syntax of HashTable, and an example. At the end, we will see a table showing the difference between ConcurrentHashMap and HashTable. What is ConcurrentHashMap in Java? ConcurrentHashMap is a class that was introduced in JDK 1.5. The ConcurrentHashMap is threadsafe as it allows multiple threads to read and write the data without locking the entire map. ConcurrentHashMap applies locks only at the bucket level, called a fragment, while ...
Read MoreHow to make a singleton enum in Java?
In Java, an enum is a special class used to represent a group of constants (that cannot be changed, like a final variable), such as Days: SUNDAY, MONDAY, TUESDAY, etc. Following is the syntax to create an Enum class in Java: enum ClassName { VALUE1, VALUE2, VALUE3, // ... VALUEN; } Where, enum is a reserved keyword in Java used to define an enum class, ClassName is the name of the enum, and VALUE1, VALUE2, VALUE3, ..., VALUEN are the ...
Read MoreHow to read the data from a properties file in Java?
Java supports file-handling; it provides various classes that provide various methods to read, write, update, and delete data from files in our local system. A properties file is a simple text file with a ".properties" extension that contains configuration data in the form of key-value pairs. It is mostly used in Java applications to manage settings such as database configuration, application messages, or environment variables. How to read Data from a Properties File in Java? To read data from the properties file, you can use the Properties class in Java. This is a subclass of the Hashtable class and it represents a persistent ...
Read MoreHow To Check Whether a Number is a Mersenne Number or Not in Java?
What is a Mersenne Number? A Mersenne number is a positive integer that is obtained using the expression M(n)= 2n-1, where 'n' is an integer. If you keep any value of n (e.g., 0, 1, 2, 3) in the above expression, the result will be a Mersenne number. For example, consider n = 2 and calculate the expression 22 - 1. The result is 3, which is a Mersenne number. Not all Mersenne numbers are prime (e.g., 24 - 1 = 15) is a mersenne number, which is not prime. Here are some other examples of Mersenne numbers: ...
Read MoreJava Program to Check if a given Class is an Anonymous Class
The type of nested class that has no name is called an anonymous class. Before diving into a Java program to check if a given class is an anonymous class, we need to understand what is a nested class. Let's discuss this in detail. What is a Java Nested Class? A class created within another class in Java is called a nested class. We know that we cannot declare a Java class private, but we can define a nested class as private. There are two types of nested classes in Java: static and non-static. The static nested class is defined ...
Read MoreJava Program to Add the data from the Specified Collection in the Current Collection
In Java, a collection is an object that allows us to group several numbers of objects as a single unit. The Collection interface is the root of the collection framework. We can perform various operations on collection like adding, removing, iterating, searching and retrieving objects. In this article, we will discuss Java programs to add data from the specified collection to the current collection with the help of addAll() method. Using addAll() method of Collection Interface The addAll() method of Collection interface adds data from a specified collection into current collection. It returns a boolean value, which is TRUE if the ...
Read MoreJava Program to Check Array Bounds while inputting Elements into the Array
Array is a linear data structure that is used to store a group of elements with similar data types. It stores data in a sequential manner. Once we create an array, we can't change its size, i.e., it is of fixed length. This article will help you to understand the basic concept of arrays and array bounds in Java. Also, we will discuss Java programs to check array bounds while inputting elements into the array. Array and Array Bound We can access elements of an array by its index. Suppose we have an array of length N, then ...
Read MoreJava Program to Access all Data as Object Array
Array is a linear data structure that is used to store a group of elements with the same data type. We can create an array with primitive datatypes, and since a class is considered a user-defined datatype in Java, it is also possible to create an array of objects. In this article, we are going to discuss object arrays. First of all, let's discuss what is an object array, in Java. What is Object array or Array of Objects An array of objects contains reference variables of objects.We follow the same syntax to create an array of primitives and an array ...
Read MoreJava Program for Rotate the Matrix Right by K times
Array is a linear data structure that is used to store a group of elements with similar data types. It stores data in a sequential manner. When we create an array of two dimensions, i.e., rows and columns, we call it a matrix. In this article, we will create a matrix of M x N and try to rotate it right by K times. Here, M and N are the size of the row and column, respectively. K is the number of times we want to rotate the matrix. Example Scenarios Let's understand what matrix rotation is with the following ...
Read MoreJava Program for Int to Char Conversion
The given task is to write a Java program that converts an integer into a character. The int and char are primitive datatypes of Java. The int is a 32-bit signed datatype used to store whole numbers, and char holds 16-bit unsigned Unicode characters. The int and char keywords are used to declare an integer variable and a character variable, respectively. We store character variables in a single quotation (' '). Example Scenario To understand the problem statement, let's see an example scenario: Input: int num1 = 83; Output: ch = 'S' Here, num1 is the name of a ...
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