使用bash文件时如何从Java中的控制台获取参数？

Question

I have a java project that I launch using a bash file :

#!/usr/bin/env bash

java -classpath logger/bin:banking/bin:testframework/bin test.RunTest

I launch my bash in my terminal (in ubuntu) :

firefrost@firefrost-PC:~/ProjetPOO3A$ bash test.sh banking.Account

In my main, I try to get arguments as :

public class RunTest {

public static void main(String[] args) {

    System.out.println(args.length);
    for(int i = 0; i < args.length; i++)
    {
...

The problem is that args.length is 0 when it should be 1 because I passed the argument "banking.Account" in my console.

If I put the argument in the bash file :

#!/usr/bin/env bash

java -classpath logger/bin:banking/bin:testframework/bin test.RunTest banking.Account

my main recognize the argument and the System.out.println outputs 1.

Why is the argument in the console not taken into account?

Answer 1

There is no problem in Java code. Your parameters are not propagated to java command in shell script.

#!/usr/bin/env bash
java -classpath logger/bin:banking/bin:testframework/bin test.RunTest "$@"

The $@ variable contains all parameters passed to shell script.

Answer 2

Command line arguments to a bash script can be accessed with $1 , $2 , etc . Here's a fuller explanation .

Try updating your script as follows:

#!/usr/bin/env bash

java -classpath logger/bin:banking/bin:testframework/bin test.RunTest $1

Answer 3

You forget to process the argument in the bash file.

You can access them by using $1, $2, $3, $... variables.

For example writing ./my.sh test test2 $1 will contain test and $2 test2

So change your script to

#!/usr/bin/env bash
java -classpath logger/bin:banking/bin:testframework/bin test.RunTest $1

Answer 4

Add "$@" to pass the arguments to the program:

#!/bin/bash

java -classpath logger/bin:banking/bin:testframework/bin test.RunTest "$@"

Don't forget the quotes around $@ so bash will "protect" each argument:

@

Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is, "$@" is equivalent to "$1" "$2" ... If the double-quoted expansion occurs within a word, the expansion of the first parameter is joined with the beginning part of the original word, and the expansion of the last parameter is joined with the last part of the original word. When there are no positional parameters, "$@" and $@ expand to nothing (ie, they are removed).

See bash man .