Running C++ applications with TotalCross

Introduction

We hope you learn how to use TotalCross Runtime and Process implementations. See more about:

• Java 7 Runtime class

• Java 8 Process class

These implementations work only for Linux platforms

Requirements

Can compile C ++ applications and finish Get Started:

Running C++ applications with TotalCross

Guide

Use external codes with Totalcross:

Step 1: create a blank project based in HelloWorld of VS Code plugin (we named it RunningCpp)

Step 2: create an I/O sample in C++, in our case we did:

#include <iostream>
#include <string>

int main()
{
    std::string input;
    std::getline(std::cin, input);
    std::cout << "\nI received: " + input + "\n";
    return 0;
}

It's a simple application to get an I/O input and shortly thereafter return it as output.

Step 3: compile (something like this):

Step 4: inside initUI method at RunningCpp class, create a label to show the results:

// Label to show the results
Label label;
label = new Label();
label.setBackForeColors(Color.WHITE,  Color.BLACK);

Step 5: create a child process:

// Process initialization
Process process = null;

Step 6: output to the target program:

// Output to program
byte[] output = "Take the output!!!\n".getBytes();              // convert string to
                                                                // byte array 
try {
    process = Runtime.getRuntime().exec("./io");                // execute your
                                                                // application (sh like)
    process.getOutputStream().write(output, 0, output.length);  // write output into 
                                                                // output strem
    process.waitFor();                                          // blocking method 
                                                                // (wait io finish)
} catch (IOException ioe) {
    ioe.printStackTrace();
} catch (InterruptedException ie) {
    ie.printStackTrace();
};

Step 7: read the C++ program output as input to TotalCross application

// Input from program
String input;
try {
    // Read line by line the buffered stream
    LineReader lineReader = new LineReader(Stream.asStream(process.getInputStream()));
    while ((input = lineReader.readLine()) != null) {
        label.setText(input);
    }
} catch (IOException ioe) {
    ioe.printStackTrace();
};

// Add label to window
add(label, CENTER, CENTER);

Step 8: run TotalCross: Package with VS Code plugin or run mvn package in your terminal.

Step 9: copy C++ binary to target folder (something like):

Step 10: run your program!!!

See more

See our article about how to run RS232 protocol. See the full code:

package com.totalcross;

import java.io.IOException; 
import java.lang.Process;

import totalcross.ui.Label; 
import totalcross.ui.MainWindow; 
import totalcross.ui.gfx.Color; 

import totalcross.io.LineReader; 
import totalcross.io.Stream; 

import totalcross.sys.Settings;

public class RunningCPP extends MainWindow {
    public RunningCPP() {
        setUIStyle(Settings.MATERIAL_UI);
    }
    
    @Override
    public void initUI() {
        // Label to show the results
        Label label;
        label = new Label();
        label.setBackForeColors(Color.WHITE,  Color.BLACK);
    
        // Process initialization
        Process process = null;
    
        // Output to program
        byte[] output = "Take the output!!!\n".getBytes();              // convert string to
                                                                        // byte array 
        try {
            process = Runtime.getRuntime().exec("./io");                // execute your
                                                                        // application (sh like)
            process.getOutputStream().write(output, 0, output.length);  // write output into 
                                                                        // output strem
            process.waitFor();                                          // blocking method 
                                                                        // (wait io finish)
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (InterruptedException ie) {
            ie.printStackTrace();
        };
    
        // Input from program
        String input;
        try {
            LineReader lineReader = new LineReader(Stream.asStream(process.getInputStream()));
            while ((input = lineReader.readLine()) != null) {
                label.setText(input);
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        };
    
        // Add label to window
        add(label, CENTER, CENTER);
    }
}

References

• Java 7 Runtime class
• Java 8 Process class