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Programming Articles
Page 2369 of 2547
Data types ranges and their macros in C++
Given the task is to find the memory range of the different data types, that what range of value a data type can store the value from minimum value to maximum value. There is memory range of data type from in which value of data can be stored. It is difficult to remember the large range of value so C++ has macros for represent these numbers, from macros these large numbers can be directly assigned to variable without typing the whole Number range. Example 'char'(signed) is character data type and has a range of -128 to +128 and ...
Read MoreHow can we avoid compilation errors in JShell in Java 9?
JShell is an interactive tool that enables us to execute java code and displays the output instantly. JShell is the REPL(Read-Evaluate-Print-Loop) tool that runs from the command-line prompt. If we need to avoid the compilation-errors in JShell, then we must declare those variables before using it. The error message in JShell can use the notation "^--^" to highlight an error.In the below code snippet, the declaration of an int variable "div" attempts to use variables: num1, and num2 that has not been declared, so JShell reports a compilation error, indicating that the compiler was unable to find those variables.C:\Users\User>jshell | ...
Read MoreWhat are the components in a module-info file in Java 9?
A module is an independent unit of application that represents a single functionality. A module contains three important componentsName: To uniquely identify itDependencies: Other modules in which it depends onExported packages: Packages which are open for external applicationIn order to declare a module, we need to add the "module-info.java" file to the root source code. The components of the "module-info.java" file includes "name", "requires", "exports", and "exports to".Below is the template of "module-info.java" filemodule { requires ; requires ; ... exports ; exports ; ... exports to ; }Name: It is ...
Read MoreHow can we display all module names in Java 9?
In Java 9, the module concept has introduced. It is a named, self-describing collection of code and data. The code can be organized as a set of packages containing types like java classes and interfaces, and data includes resources and other kinds of static information. A module contains a name, dependencies, and exported packages.Syntaxmodule com.tutorialspoint.mymodule { // some statements }In the below example, we can able to display all module names by using the ModuleLayer class.Examplepublic class AllModulesNamesTest { public static void main(String args[]) { ModuleLayer.boot().modules().forEach((module) -> { ...
Read MoreHow to print the pattern of stars in JShell in Java 9?
JShell is a REPL tool introduced in Java 9 that allows us to execute Java code and getting results immediately. We can evaluate expressions or simple algorithms without creating a new project, compile or build it by using JShell. We can also execute expressions, use imports, define classes, methods, and variables. It is a part of Java 9 JDK but not JRE.We can start JShell session in command-prompt by simply typing jshell. We can use different commands: /exit to quit the JShell session, reset/reload JShell anytime by typing /reset, and /reload, /import to list the imports, etc.In the below example, ...
Read MoreWhat are Compact Strings in Java 9?
Since Java 9, the JVM optimizes strings by using a new feature called Compact Strings. Instead of having a char[] array, a string can be represented as a byte[] array. We can use either UTF-16 or Latin-1 to produce either one or two bytes per character. If JVM detects the string contains only ISO-8859-1/Latin-1 characters, then string uses one byte per character internally.The string can be represented with a compact string or not is detected when the string is created. This feature has enabled by default and switches off using the -XX:-CompactStrings. It doesn't revert to a char[] implementation and ...
Read MoreHow to display all stack frames of the current thread in Java 9?
Stack Walking API can provide a flexible mechanism to traverse and extract information from call stacks that allow us to filter and access frames in a lazy manner. StackWalker class is an entry point to Stack Walking API. The stack trace is a representation of a call stack at a certain point of time in which each element represents a method invocation. It contains all invocations from the start of a thread until the point it’s generated.In the below example, we can print/display all stack frames of the current thread by using StackWalker API.Exampleimport java.lang.StackWalker.StackFrame; import java.lang.reflect.Method; import java.util.List; import java.util.stream.Collectors; public ...
Read MoreWhat is Variable Handle in Java 9?
Variable Handle is a variable or reference to a set of variables, including other components of a static field, non-static fields, and outer array elements in the heap data structure. It means that Variable Handle is similar to the existing Method Handle. It can be represented by using java.lang.invoke.VarHandle class. We can use java.lang.invoke.MethodHandles.Lookup static factory method to create Variable Handle objects. It can also be used to access a single element in the array, and byte[] array.Syntaxpublic abstract class VarHandle extends ObjectExampleimport java.lang.invoke.MethodHandles; import java.lang.invoke.VarHandle; import java.util.Arrays; public class VarHandleTest { public static void main(String ...
Read MoreWhat is the importance of the ProcessHandle interface in Java 9?
ProcessHandle interface introduced in Java 9. It allows us to perform actions and check the state of a process that relates. This interface provides the process’s native process ID (pid), start time, accumulated CPU time, arguments, command, user, parent process, and descendants.ProcessHandle interface allows us to perform the following actions.It returns a ProcessHandle.Info containing further information about a processThe Pid of a processIf it is aliveRetrieve a snapshot of the direct children of a processRetrieve a snapshot of all descents of a processRetrieve a snapshot of all currently running processesAllow the process to be destroyedIt returns a CompletableFuture with a ProcessHandle for when the ...
Read MoreWhat is Http/2 Client in Java 9?
Http/2 Client API introduced in Java 9. It has more performance improvements over Http/1.1 and also supports server-side push events. This makes the website efficient and faster to browse. Http/2 Client is an incubator module named jdk.incubator.httpclient, which means that all features are still not finalized, and new changes may come in future versions of java. It exports jdk.incubator.http package that contains all public APIs.To use Http/2 Client, we need to use the incubator module, we simply pass the httpclient module into JShell using the "–add-modules" command as belowC:\>jshell -v --add-modules jdk.incubator.httpclient | Welcome to JShell -- Version 9.0.4 | For an introduction type: /help introExamplejshell> import jdk.incubator.http.*; jshell> HttpClient httpClient ...
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