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The Pi is a special mathematical value, approximately 3.14159, that is often used in calculations related to circles and geometry. In C++, we need to understand how to access and use this constant in our programs. In this article, we will show how to use the PI constant in a C++ program. The PI constant is available in the cmath header file. We will explain how to use PI to calculate values like the area or circumference of a circle. How to Use Pi in C++ There are multiple ways to use the Pi constant in C++. ... Read More
In this article, we will learn how to pass command line parameters in C++. The command line argument is a parameter that is passed to a program when it is invoked by the command line or terminal. Parsing Command Line Parameters in C++ In C++, we can pass the command line argument using the argc and argv[] parameters that are passed to the main function. Where argc refers to the number of arguments passed, and argv[] is a pointer array that points to each argument passed to the program. We can use loops to iterate and parse the command line ... Read More
In this article, we will learn to import external libraries in JShell in Java 9. JShell is an interactive tool to learn the Java language and prototype Java code. This tool works on the principle of REPL (Read-Evaluate-Print-Loop). Default Imports in JShell By default, JShell automatically imports a few useful Java packages when the JShell session is started. We can type the command /imports to get a list of all these imports. jshell> /imports | import java.io.* | import java.math.* | import java.net.* | import java.nio.file.* | import java.util.* | import java.util.concurrent.* | import java.util.function.* | import java.util.prefs.* | import ... Read More
In this article, we will learn about the new methods that have been added to the Arrays class in Java 9. First, we will learn about arrays, and then the new methods added to the equals(), compare(), and mismatch() methods with examples. Arrays Java provides a data structure called the Array, and they are used to store multiple values of the same datatype in a single variable. The Arrays class can contain various methods for manipulating arrays and also contains static factory methods that allow arrays to view as a list. Creating an instance of an Array with a variable ... Read More
In this article, we will learn about useful commands in JShell. Java 9 has introduced a new interactive tool called JShell. This tool can be used to execute, test user-friendly and easy way of Java classes, interfaces, enums, objects, statements and etc. Different Useful Commands in JShell Below are some of the important commands in JShell: /open /var /types /methods /list /help /open To execute a script after JShell has started, we will use ... Read More
JShell is a Read-Evaluate-Print Loop (REPL) that evaluates declarations, statements, and expressions as we have entered and immediately shows the results. This tool is run from the command prompt. Below, we can define expressions, variables, and methods in JShell. Expression The combination of variables, operators, and methods is known as an Expression in Java. They perform some logic that evaluates to a single value. int a=5, b=10, c=0; c=a+b; Here, "a+b" is an expression that evaluates the value of c as 15. Expression in JShell We can type any valid Java expression in JShell. The expression ... Read More
In this article, we will learn about the use of the Cleaner class in Java 9. Below, we will first tell the basic usage and then we will know how we can use the Cleaner method practically. Garbage Collector An Object that has been created during the program execution is automatically removed by the Garbage Collector (GC). When an object not referenced by any thread and when JVM determines that this object can't be accessed, then it can be eligible for garbage collection. The finalize() method The Object class has a finalize() method, which is automatically called by GC before it attempts to remove the ... Read More
Java 9 provides factory methods to create immutable lists, sets, and maps. It can be useful to create empty or non-empty collection objects. In Java 8 and earlier versions, we can use collection class utility methods like unmodifiableXXX to create immutable collection objects. If we need to create an immutable list, then use the Collections.unmodifiableList() method. What does Immutable mean? An object is considered immutable if its state cannot change after it is constructed. Any modification creates a new object instead. String name = "TutorialsPoint"; name = name + "10"; Here, "TutorialsPoint" is an immutable string, and we cannot modify it directly. Instead, we use the ... Read More
Java Shell or JShell is an official REPL(Read-Evaluate-Print-Loop) introduced with Java 9. It provides an interactive shell for quickly prototyping, debugging and without the need for the main() method or the need to compile the code before executing it. JShell is easily started by typing "jshell" in the command prompt. What are Snippets? JShell allows the execution of Java statements, variables, methods, class definitions, imports, and expressions. These pieces of Java code are referred to as snippets. Every snippet is assigned an ID(unique) that we can use later to reference it. Example Below is an example to represent a snippet ... Read More
In this article, we will learn to create an unmodifiable Set in Java 9. We will be learning about Set and unmodifiable Set, and will be learning different ways of creating an unmodifiable Set(Set.of() Method and unmodifiableSet() Method). Set In Java, a Set is an interface that inherits the Collection interface and contains no duplicate elements. A Set interface has methods to add, delete, and check the existence of an element. Some of the implementations of the Set interface are: HashSet TreeSet LinkedHashSet What is an ... Read More