CODEWITHSUNDEEP
javac#
halpme142
halpme142

Reputation: 39

Get output of a java application C#

This may be hard to understand, but I want to get the output of a java application in a console C# app.

When you start a java application with Process.Start in a C# console app, the java application takes control, and all lines are written using System.Out.Println().

I want to start a java application, make it so System.out.println() gets stored in a variable and not printed, and then reprint what the variable is with Console.WriteLine()

Allow me to rephrase. #1 Start java app in c# console app with process.start. #2 Cancel java's attempts to output what it was going to output with System.out.prinln(), and instead store it in a variable/string. #3 reprint that string using Console.WriteLine().

Redirecting standard output does not work for this.

If you are wondering, this is for minecraft bukkit.

Upvotes: 3

Views: 2401

Answers (1)

Nick Y
Nick Y

Reputation: 172

Java application:

public class JavaApplication {

    public static void main(String[] args) {
        System.out.println("Java application outputs something into stdout");
        System.err.println("Java application outputs something into stderr");
    }
}

C# application

using System;
using System.Diagnostics;

namespace CaptureProcessStdOutErr
{
  public class Program
  {
    public static void Main(string[] args)
    {
      var startInfo = new ProcessStartInfo("java", "JavaApplication") // proper path to java, main java class, classpath, jvm parameters, etc must be specified or use java -jar jarName.jar if packaged into a single jar
      {
        RedirectStandardError  = true,
        RedirectStandardOutput = true,
        UseShellExecute        = false
      };

      var process = Process.Start(startInfo);

      process.WaitForExit();

      Console.WriteLine("Captured stderr from java process:");
      Console.WriteLine(process.StandardError.ReadToEnd());
      Console.WriteLine();
      Console.WriteLine("Captured stdout from java process");
      Console.WriteLine(process.StandardOutput.ReadToEnd());
    }
  }
}

This assumes java.exe is in the PATH.

Compile JavaApplication and put JavaApplication.class file next to C# application (CaptureProcessStdOutErr.exe)

run CaptureProcessStdOutErr.exe

Output: 

Captured stderr from java process:
Java application outputs something into stderr

Captured stdout from java process
Java application outputs something into stdout

Upvotes: 4

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