1. What is JShell in Java?
Answer:
Explanation:
JShell stands for Java Shell and is an interactive Read-Evaluate-Print Loop (REPL) tool introduced in Java 9, which allows for interactive Java programming.
2. What was JShell primarily introduced for?
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Explanation:
JShell was introduced as a tool for learning Java and experimenting with Java code snippets interactively.
3. How is JShell launched?
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Explanation:
JShell is launched by entering the ‘jshell’ command in the terminal or command prompt.
4. Can JShell be used to execute multi-line Java statements?
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Explanation:
JShell can execute both single-line and multi-line Java statements, making it suitable for testing small to complex code snippets.
5. Does JShell support tab completion?
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Explanation:
JShell supports tab completion, helping users to easily complete commands, method names, and variable names.
6. What happens when you define a method in JShell?
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Explanation:
Methods defined in JShell can be immediately invoked without the need for compiling or wrapping in a class.
7. How can you view the history of your commands in JShell?
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Explanation:
The /history command in JShell displays the history of the commands and code snippets entered.
8. Can you import external libraries and use them in JShell?
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Explanation:
JShell allows importing external libraries and using them, provided that the libraries are in the classpath.
9. How do you exit JShell?
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Explanation:
The /exit command is used to exit JShell.
10. How does JShell handle undeclared variables?
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Explanation:
If a variable is used without being declared, JShell will throw an error.
11. Can JShell be used for scripting?
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Explanation:
JShell can be used for scripting, allowing users to write and execute more complex code sequences.
12. What feature does JShell provide for lengthy outputs?
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Explanation:
For lengthy outputs, JShell provides pagination, making it easier to read and navigate through the output.
13. How do you save JShell session commands to a file?
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Explanation:
The /save command followed by a filename saves the current JShell session commands to a file.
14. How can you evaluate expressions quickly in JShell?
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Explanation:
JShell allows for the quick evaluation of expressions by directly typing them into the shell.
15. Does JShell provide feedback on syntax errors?
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Explanation:
JShell provides immediate feedback on syntax errors, helping users to quickly identify and correct mistakes in their code.
16. Can JShell execute Java files directly?
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Explanation:
JShell is primarily designed for executing Java code snippets and expressions interactively, not for executing Java files directly.
17. How do you reload a previous JShell session?
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Explanation:
The /open command followed by a filename can be used to reload a previously saved JShell session.
18. How do you view the available JShell commands?
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Explanation:
The /help command in JShell provides a list of available commands and their descriptions.
19. What is a snippet in the context of JShell?
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Explanation:
In JShell, a snippet refers to a small piece of Java code, such as a variable declaration, an expression, a statement, a method, or a class definition.
20. How do you modify the classpath in JShell?
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Explanation:
The /env -class-path command is used to modify the classpath in JShell, allowing users to include additional classes and libraries.