Use of JShell script tool in java-javaTutorial-php.cn

Home

Java

javaTutorial

Use of JShell script tool in java

王林

Nov 26, 2019 am 10:41 AM

javajshellScript tool

Use of JShell script tool in java

JShell script tool is a new feature of JDK9

When will we use JShell tool? When we write very little code and are unwilling to write Class and main method are not willing to compile and run. At this time, you can use the JShell tool.

Recommended related video tutorials: java online video

Start the JShell tool and enter the JShell command directly on the DOS command line.

Use of JShell script tool in java

Next, you can write Java code. There is no need to write classes and methods. You can directly write the code in the method. At the same time, there is no need to compile and run, just press Enter

Use of JShell script tool in java

Note: The JShell tool is only suitable for testing fragmented code. To develop more content, it is recommended to write it in the method.

=Expansion of symbols

Is there something wrong with the following program?

Use of JShell script tool in java

Analysis: s = 1 is logically regarded as s = s 1. The calculation result is promoted to the int type, and an error occurs when assigning a value to the short type because the result cannot be A type with a large value range is assigned to a type with a small value range. However, s=s 1 performs two operations, and = is an operator that only operates once and has the characteristics of forced conversion. That is to say, s = 1 is s = (short)(s 1), so there is no problem with the program. The compilation is passed, and the running result is 2.

Operation of constants and variables

Is there any problem with the following program?

Use of JShell script tool in java

Analysis: b3 = 1 2, 1 and 2 are constants, which are fixed data. During compilation (compiler javac), 1 2 has been determined The result does not exceed the value range of the byte type and can be assigned to variable b3, so b3=1 2 is correct.

On the contrary, b4 = b2 b3, b2 and b3 are variables, and the values of the variables may change. During compilation, the compiler javac is not sure what the result of b2 b3 is, so it will convert the result as int The type is processed, so the int type cannot be assigned to the byte type, so the compilation fails.

Reflected in jshell:

Use of JShell script tool in java

For more related articles, you can visit: javaQuick Start

The above is the detailed content of Use of JShell script tool in java. For more information, please follow other related articles on the PHP Chinese website!

Statement

This article is reproduced at:CSDN. If there is any infringement, please contact admin@php.cn delete

带你搞懂Java结构化数据处理开源库SPLMay 24, 2022 pm 01:34 PM

本篇文章给大家带来了关于java的相关知识，其中主要介绍了关于结构化数据处理开源库SPL的相关问题，下面就一起来看一下java下理想的结构化数据处理类库，希望对大家有帮助。

Java集合框架之PriorityQueue优先级队列Jun 09, 2022 am 11:47 AM

本篇文章给大家带来了关于java的相关知识，其中主要介绍了关于PriorityQueue优先级队列的相关知识，Java集合框架中提供了PriorityQueue和PriorityBlockingQueue两种类型的优先级队列，PriorityQueue是线程不安全的，PriorityBlockingQueue是线程安全的，下面一起来看一下，希望对大家有帮助。