如何在jshell脚本中接受用户输入? [英] How to take user input in jshell script?

问题描述

如何在 jshell脚本中接受用户输入?还是我做错了什么?

How to take user input in jshell script? or what I'm doing wrong?

注意:我不正在寻找例如脚本hello.java:

Scanner in = new Scanner(System.in);

System.out.print("Enter number n1: ");
int n1 = in.nextInt();
System.out.print("Enter number n2: ");
int n2 = in.nextInt();

System.out.println("n1 + n2 = "+ (n1 +n2));

/exit

如果我在jshell中逐行输入，它会起作用，但是随后我运行jshell hello.java却没有.抛出java.util.NoSuchElementException.

It works if I type line by line in jshell, but then I run jshell hello.java it doesn't. Throws java.util.NoSuchElementException.

我得到的输出:

@myMint ~/Java $ jshell hello.java 
Enter number n1: |  java.util.NoSuchElementException thrown: 
|        at Scanner.throwFor (Scanner.java:858)
|        at Scanner.next (Scanner.java:1497)
|        at Scanner.nextInt (Scanner.java:2161)
|        at Scanner.nextInt (Scanner.java:2115)
|        at (#3:1)
Enter number n2: |  java.util.NoSuchElementException thrown: 
|        at Scanner.throwFor (Scanner.java:858)
|        at Scanner.next (Scanner.java:1497)
|        at Scanner.nextInt (Scanner.java:2161)
|        at Scanner.nextInt (Scanner.java:2115)
|        at (#5:1)
n1 + n2 = 0

我的系统: Linux Mint 18.2(x64)，JShell版本9.0.1

推荐答案

您可以解决此问题，但不能直接使用基于JShell的代码解决.

You can solve this issue, but not directly with JShell based code.

有一个项目jshell_script_executor: https://github.com/kotari4u/jshell_script_executor

您可以下载它，并在JShellScriptExecutor.java

来自

try(JShell jshell = JShell.create()){

到

// This call will map System.in in your main code
// to System.in inside JShell evaluated code
try(JShell jshell =
  JShell.builder()
    .in(System.in)
    .out(System.out)
    .err(System.err)
    .build()){

以及(也)对您的代码进行少量修改(我知道这并不是您要找的东西-我们在这里不使用Scanner)

and (also) small modification of your code (I know this is not exactly what you are looking for - we don't use Scanner here):

/* Put this code into file.jshell */
import java.io.*;

InputStreamReader read = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(read);
int n1;
System.out.print("Enter the number: ");
n1 = Integer.parseInt(in.readLine());

int n2;
System.out.print("Enter the number: ");
n2 = Integer.parseInt(in.readLine());

System.out.println("n1 + n2 = " + (n1 + n2));

您可以使其运行:

> javac src/main/java/com/sai/jshell/extension/JShellScriptExecutor.java
> java -cp src/main/java com.sai.jshell.extension.JShellScriptExecutor ./file.jshell
Enter the number: 1
Enter the number: 2
n1 + n2 = 3

嗯...实际上，它也可以与您的代码一起使用-稍作修改:

Well ... in fact it will work with your code as well - slightly modified:

/* Put this code into file_scanner.java */
import java.util.Scanner;

Scanner in = new Scanner(System.in);

System.out.print("Enter number n1: ");
int n1 = in.nextInt();
System.out.print("Enter number n2: ");
int n2 = in.nextInt();

System.out.println("n1 + n2 = "+ (n1 +n2));

尝试一下

> java -cp src/main/java com.sai.jshell.extension.JShellScriptExecutor ./file_scanner.java
Enter number n1: 1
Enter number n2: 2
n1 + n2 = 3

这篇关于如何在jshell脚本中接受用户输入?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！