Can't get runtime.exec working on android

Question

I can't seem to get runtime.exec working in my android app. I've tried it with a host of shell utilities, here's the code I'm using:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    filesPrinter = (Button) findViewById(R.id.print_files);
    filesPrinter.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                Process proc = Runtime.getRuntime().exec("ls");
                out = new BufferedWriter(new OutputStreamWriter(proc.getOutputStream()));
                in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
                String line;
                while((line = in.readLine()) != null) {
                    System.out.println(line);
                }
                System.out.println("Done reading");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    });
 }

I don't get an error, but also do not get anything in logcat.

What is the error? And where is question? Did you read SO FAQ before posting it? — ArtemStorozhuk, Jun 22 '12 at 21:16
@Astor the question seems a very valid one, even if more details on the error could help indeed. — assylias, Jun 22 '12 at 21:19
I've made an edit, there is no error, but I don't get any output to logcat — MEURSAULT, Jun 22 '12 at 21:19
possible duplicate ? http://stackoverflow.com/questions/4618631/android-runtime-getruntime-exec-to-nav-through-directories — Zakaria, Jun 22 '12 at 21:23
Did you try to execute another command? For example try to execute `ls -l`. Did you debug that code? — ArtemStorozhuk, Jun 22 '12 at 21:24

score 2 · Accepted Answer · answered Jun 22 '12 at 21:46

2

The problem ended up being a bug with the eclipse logcat. Using adb logcat, I could see everything that was supposed to be outputted. For some reason, logcat on eclipse showed that it was connected but was not receiving any application level output from the emulator.

answered Jun 22 '12 at 21:46

MEURSAULT

8,307
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Come to think of it, I think LogCat does not display data from the standard error stream (which is where `e.printStackTrace()` outputs). Try `System.out.println(Arrays.toString(e.getStackTrace()));` instead, or, better yet, any of the `Log` methods. – mikołak Jun 22 '12 at 22:58

score 0 · Answer 2 · answered Jun 22 '12 at 21:22

0

Maybe your current working directory (which is what ls scans without any parameters) simply contains no files. Try providing a path as a command argument.

answered Jun 22 '12 at 21:22

mikołak

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I'm assuming that by "nothing" you mean "nothing except >>Done reading<<", correct me if I'm wrong. – mikołak Jun 22 '12 at 21:23

t0mm13b · Answer 3 · 2012-06-22T21:52:31.990

Think you're missing a proc.waitFor()....

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    filesPrinter = (Button) findViewById(R.id.print_files);
    filesPrinter.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                Process proc = Runtime.getRuntime().exec("ls");
                out = new BufferedWriter(new OutputStreamWriter(proc.getOutputStream()));
                in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
                String line;
                while((line = in.readLine()) != null) {
                    System.out.println(line);
                }
                System.out.println("Done reading");
                //
                proc.waitFor(); // THIS!!!
                //
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    });
 }

Can't get runtime.exec working on android

3 Answers3