Capture the output from Java Runtime.getRuntime().exec()

By using Java Runtime.getRuntime().exec(), you can start an external binary from JRE. If there are some outputs or errors and you don't handle them, you will face some potential problems such as buffer overflow and don't have a clue where to debug. The following class can be used to catch/process the outputs from Runtime.getRuntime().exec()

class StreamReader extends Thread {
Reader input;
int c;
char[] chars = new char[1000];
String line;
String threadName;

public StreamReader(String threadName, Reader input) {
this.input = input;
this.threadName = threadName;
}

public void run() {
try {
while ((c = input.read(chars)) != -1) {
line = new String(chars, 0, c);
System.out.print(threadName + " " + line);
}
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
}

When you start the process, you can call with

Process pro1 = Runtime.getRuntime().exec(cmd, null, new File(StartInPath));
BufferedReader brErr1 = new BufferedReader(new InputStreamReader(pro1.getErrorStream()));
BufferedReader bdIn1 = new BufferedReader(new InputStreamReader(pro1.getInputStream()));
new StreamReader("[err]", brErr1).start();
new StreamReader("[out]", bdIn1).start();