java 如何在 Java 9 的 JShell 中创建类

如何在 Java 9 的 JShell 中创建类

原文:https://www . geesforgeks . org/how-to-create-a-class-in-jshell-of-Java-9/

JShell 是一个交互式的 Java Shell 工具，它允许我们从 Shell 中执行 Java 代码并立即显示输出。JShell 是一个 REPL(读取评估打印循环)工具，从命令行运行。 Jshell 有能力创建一个类，通过这个类可以减少所有的工作来编写一个完整的 Java 代码来检查这个类是否正常工作。

A 类根据用户需求包含不同的方法和变量，但由于一些错误程序无法工作。但是在 JShell 的帮助下，这可以更有效地解决，并且耗时更少。

示例:

In this example, class A is created successfully and one can call the class methods by creating an object of class A.

```java C:\Windows\SysWOW64>jshell | Welcome to JShell -- Version 13.0.1 | For an introduction type: /help intro jshell> class A{ ...> int x; ...> int y; ...> void get(int a, int b) ...> { ...> x=a; ...> y=b; ...> } ...> void show() ...> { ...> System.out.println("sum="+(x+y)); ...> } ...> }

| created class A ```
In this example, due to ‘;’, an error occurs and this can be solved it easily because the line of code is small and easy.

java jshell> class A{ ...> int x; ...> int y; ...> void get(int a, int b) ...> { ...> x=a; ...> y=b; ...> } ...> void show(); ...> { ...> System.out.println("sum="+(x+y)); ...> } ...> } | Error: | missing method body, or declare abstract | void show(); | ^----------^
Example to access the methods of the class:

java jshell>A a=new A(); a ==> A@42dafa95 jshell>a.get(10, 20); jshell>a.show(); sum=30
In the above examples, the objects of class A is created and denoted by ‘a’ and we call the get and show methods. We can also override the methods of class A. After overriding the methods, a message will be displayed that “the method is modified” and now we can call the modified methods and get the answers.

java jshell> void show(); ...> { ...> System.out.println("sum="+(x-y)); ...> } | modified method show(int, int)