Give and get java program input / output from source

Question

How can I write a program that will run another java program (should call this program), give input to this program from this program and get the output and print the output to a file.

Answer 1

Use ProcessBuilder

Example:

ProcessBuilder pb = new ProcessBuilder("myCommand", "myArg1", "myArg2");
Process p = pb.start();
InputStream in = p.getInputStream();
OutputStream out = p.getOutputStream();


// Write to input of the program using outputstream here
...

// Read output of program from input stream here
// ...


FileOutputStream fileOut = new FileOutputStream("output.txt");
BufferedInputStream bIn = new BufferedInputStream(in);

byte buf = new byte[4096];
int count;

while ((count = bIn.read(buf)) != -1) {
    fileOut.write(buf, 0, count);
}

...
fileOut.close();
bIn.close();

// Exception handling is left as an exercise for the reader :-P