I know there are many threads about this, but none of them worked for me. Here is what I am trying to do:
Javac and run a file from my java code. It works for Windows but I would like to make it also work on UNIX. Here the code:
if(os.equals("win")){
//For Windows
try {
Runtime.getRuntime().exec(
"cmd /c start cmd.exe /K "
+ "\"cd " + path + "&& "
+ "javac " + name + ".java && "
+ "echo ^>^>" + name + ".java " + "outputs: &&"
+ "echo. &&"
+ "java " + name + " && "
+ "echo. &&"
+ "pause && "
+ "exit\"");
} catch (IOException e) {
System.out.println("Didn't work");
}
}else{
try {
//TODO make it work for UNIX
Runtime.getRuntime().exec("");
} catch (IOException e) {
System.out.println("Didn't work");
}
}
The problem is, that on UNIX systems it acts "unpredictable"
For exemple:
Runtime.getRuntime().exec("open image.png");
Opens the image but
Runtime.getRuntime().exec("javac Test.java");
Runtime.getRuntime().exec("echo 'hello'");
It does nothing. No Massage.
I am grateful for any input.
UPDATE------------------------------------------------------------
It seems like in contrast to Windows CMD, Terminal needs a InputStreamReader to display what happened in exec. I found this code in another thread and now at least I get some output from the exec Terminal.
String line;
Process p = Runtime.getRuntime().exec( "echo HelloWorld2" );
BufferedReader in = new BufferedReader(
new InputStreamReader(p.getInputStream()) );
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
But things still remain misterious, because executing
Process p = Runtime.getRuntime().exec("javac Test.java");
works and generates a Test.class file. But
Process p = Runtime.getRuntime().exec("javac Test.java && java Test");
does nothing.(Nothing happens. Terminal "executes" without error massages.) Typing this manually in Terminal builds and runs as expected. What am I missing?
解决方案
I don't have a Linux system here to play with, but I'm pretty certain that the second command above is trying to compile Java files named "Test.java", "&&", "java" and "Test"; in other words the Runtime.exec() method treats arguments literally instead of applying shell interpretation.
You could probably get it to work with something along the lines of:
Process p = Runtime.getRuntime().exec(
new String[] { "sh", "-c", "javac Test.java && java Test" });