System.console is an example of a class that cant be extended. what is the reason for this?
Running and debugging JavaVisual Studio Code allows you to debug Java applications through the Debugger for Java extension. It's a lightweight Java debugger based on Java Debug Server, which extends the Language Support for Java™ by Red Hat. Show
Here's a list of supported debugging features:
The Java debugger is an open-source project, which welcomes contributors to collaborate through GitHub repositories:
If you run into any issues when using the features below, you can contact us by entering an issue. InstallTo get the complete Java language support in Visual Studio Code, you can install the Extension Pack for Java, which includes the Debugger for Java extension. Install the Extension Pack for Java
ConfigureBy default, the debugger will run out-of-box by automatically finding the main class and generating a default launch configuration in memory to launch your application. If you would like to customize and persist your launch configuration, you can select the create a launch.json file link in the Run and Debug view. The launch.json file is located in a .vscode folder in your workspace (project root folder). For more details on how to create the launch.json, read Launch configurations; for more details on configuration options for Java, you can read Configuration options. The debugger extension provides multiple ways to run and debug your Java application. Run from CodeLensYou will find Run|Debug on the CodeLens of your main() function. Another way to start debugging is to select Run Java or Debug Java menu from the top editor title bar. Run from pressing F5Pressing F5, the debugger will automatically find the entry point of your project and start debugging. You can also start a debugging session from the Run and Debug view from the side bar of VS Code. See more at Debugging in VS Code. Debugging single filesIn addition to support for debugging Java projects managed by build tools, VS Code also supports for debugging single Java files without any project. Debug session inputsThe default Debug Console in VS Code doesn't support inputs. If your program need inputs from a terminal, you can use the Integrated Terminal (⌃` (Windows, Linux Ctrl+`)) within VS Code or an external terminal to launch it. You can also use the user setting java.debug.settings.console to configure a global console for all Java debug sessions. BreakpointsThe Debugger for Java supports various breakpoints, such as line breakpoints, conditional breakpoints, data breakpoints, logpoints. Breakpoint - Conditional breakpointWith the help of expression evaluation, the debugger also supports conditional breakpoint. You can set your breakpoint to break when expression evaluates to true. Breakpoint - Data breakpointYou can have the debugger break when a variable changes its value. Note that the data breakpoint can only be set inside a debug session. This means you need to launch your application and break on a regular breakpoint first. You can then pick a field in the VARIABLES view and set a data breakpoint. Breakpoint - LogpointsLogpoints is also supported by Java Debugger. Logpoints allow you to send output to Debug Console without editing code. They're different from breakpoints because they don't stop the execution flow of your application. Expression evaluationThe debugger also lets you evaluate expressions in the WATCH window as well as the Debug Console. Hot Code ReplaceAnother advanced feature the debugger supports is 'Hot Code' replacement. Hot Code Replace (HCR) is a debugging technique whereby the Debugger for Java transmits the class changes over the debugging channel to another Java Virtual Machine (JVM). HCR facilitates experimental development and fosters iterative trial-and-error coding. With this new feature, you can start a debugging session and change a Java file in your development environment, and the debugger will replace the code in the running JVM. No restart is required, which is why it's called "hot". Below is an illustration of how you can use HCR with Debugger for Java in VS Code. You may use the debug setting java.debug.settings.hotCodeReplace to control how to trigger Hot Code Replace. The possible setting values are:
Step filteringStep filter is supported by the extension to filter out types that you do not want to see or step through while debugging. With this feature, you can configure the packages to filter within your launch.json so they could be skipped when you step through. Configuration optionsThere are many options and settings available to configure the debugger. For example, configuring the JVM arguments and environment variables is easily done with launch options. Consult the documentation for the Language Support for Java™ by Red Hat extension for help with setting up your project. For many commonly used setups, there are samples available in VS Code Java Debugger Configuration. The document explains how the Java debugger automatically generates configurations for you, and if you need to modify them, how to do so with Main class, different arguments, environment, attaching to other Java processes, and usage of more advanced features. Below are all the configurations available for Launch and Attach. For more information about how to write the launch.json file, refer to Debugging. Launch
Attach
User settings
TroubleshootingIf you encounter issues when using the debugger, a detailed troubleshooting guide can be found in the vscode-java-debug GitHub repository. Common issues explained include:
Feedback and questionsYou can find the full list of issues at the vscode-java-debug repository. You can submit a bug or feature suggestion and participate in the community driven vscode-java-debug Gitter channel. Next stepsRead on to find out about:
And for Java:
12/9/2021 What class access modifier means that access to the class is not limited?The following six accessibility levels can be specified using the access modifiers: public : Access is not restricted. protected : Access is limited to the containing class or types derived from the containing class. internal : Access is limited to the current assembly.
When a class inherits from a base class it is known as what type of class?Inheritance enables you to create new classes that reuse, extend, and modify the behavior defined in other classes. The class whose members are inherited is called the base class, and the class that inherits those members is called the derived class. A derived class can have only one direct base class.
What happens when a method overrides another method?The overriding method has the same name, number and type of parameters, and return type as the method that it overrides. An overriding method can also return a subtype of the type returned by the overridden method. This subtype is called a covariant return type.
What class should you extend in order to create your own exception that you can throw?To create a custom exception, we have to extend the java. lang. Exception class. Note that we also have to provide a constructor that takes a String as the error message and called the parent class constructor.
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