Open git bash and run command in java on Windows

You just have to change the paths and the git command. But the git-bash output is printed on a separate .txt file because I couldn't read it in any other way.

public class GitBash {

    public static final String path_bash = "C:/Program Files/Git/git-bash.exe";

    // Create a file Output.txt where git-bash prints the results
    public static final String path_file_output_git_bash =
            "C:/Users/Utente/Documents/IntelliJ-DOC/IntelliJ_project/Prova/src/main/Git-bash/Output.txt";

    public static void main(String[] args) {
        // Path to your repository
        String path_repository = "cd C:/Users/Utente/Documents/Repository-SVN-Git/Bookkeeper";
        // Git command you want to run
        String git_command = "git ls-files | grep .java | wc -l";

        String command = path_repository + " && " + git_command + " > " + path_file_output_git_bash;

        runCommand(command);
    }

    public static void runCommand(String command) {
        try {
            ProcessBuilder processBuilder = new ProcessBuilder();
            processBuilder.command(path_bash, "-c", command);

            Process process = processBuilder.start();

            int exitVal = process.waitFor();
            if (exitVal == 0) {
                System.out.println(" --- Command run successfully");
                System.out.println(" --- Output = " + readFileTxt());

            } else {
                System.out.println(" --- Command run unsuccessfully");
            }
        } catch (IOException | InterruptedException e) {
            System.out.println(" --- Interruption in RunCommand: " + e);
            // Restore interrupted state
            Thread.currentThread().interrupt();
        }
    }

    public static String readFileTxt() {
        String data = null;
        try {
            File myObj = new File(path_file_output_git_bash);
            Scanner myReader = new Scanner(myObj);
            while (myReader.hasNextLine()) {
                data = myReader.nextLine();
            }
            myReader.close();
        } catch (FileNotFoundException e) {
            System.out.println(" --- An error occurred");
            e.printStackTrace();
            }
            return data;
        }
    }
}

--- EDIT 2021/03/26 ---

Answer without the needs of a .txt file : Read output git-bash with ProcessBuilder in Java

This will execute a bash script on Windows if you have Git installed without the need to write the output to a temp file.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringJoiner;

public class BashRunner
{
    public static final String BASH_PATH = "C:/Program Files/Git/bin/sh.exe";
    public static final String SCRIPT_NAME = "C:/temp/test-script.sh";

    public static void main(String[] args)
    {
        String output = runCommand(BASH_PATH, "-c", SCRIPT_NAME);
        System.out.println(output);
    }

    public static String runCommand(String... params)
    {
        ProcessBuilder pb = new ProcessBuilder(params);
        Process p;
        StringJoiner joiner = new StringJoiner(System.getProperty("line.separator"));
        try
        {
            p = pb.start();

            final BufferedReader reader = new BufferedReader(
                new InputStreamReader(p.getInputStream()));

            reader.lines().iterator().forEachRemaining(joiner::add);

            p.waitFor();
            p.destroy();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        return joiner.toString();
    }
}

The contents of the script:

#!/bin/bash

echo "hello"
echo "world!"

Output:

hello
world!

Also, this will execute Git Bash silently in that you won't get a popup window while processing.

Do you need the bash terminal to pop up? If not, this could work

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class testprog {
    public static void main(String args[]) {
        String s;
        Process p;
        try {
            p = Runtime.getRuntime().exec("ls -aF");
            BufferedReader br = new BufferedReader(
                new InputStreamReader(p.getInputStream()));
            while ((s = br.readLine()) != null)
                System.out.println("line: " + s);
            p.waitFor();
            System.out.println ("exit: " + p.exitValue());
            p.destroy();
        } catch (Exception e) {}
    }
}