Ping a host in Android:
“ping -c 1 127.0.0.1”
-c 1: The ping times.

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boolean flag = false;

Runtime run = Runtime.getRuntime();

Process proc = null;

try {

	proc = run.exec("ping -c 1 127.0.0.1");

	int result = proc.waitFor();

	if (result == 0) {

		flag = true;

	} else {

		flag = false;

	}

} catch (IOException e) {

	e.printStackTrace();

} catch (InterruptedException e) {

	e.printStackTrace();

} finally {

	proc.destroy();

}

Ping codes is simple, but:
1, you must run it in background thread since Process.waitfor() will blocks current thread.
2, And you should control the the execution time for Process.waitfor().

The solutions of above 2 issues could be:
1, AsyncTask to run Process.waitfor() in background;
2, Handler.sendEmptyMessageDelayed() to send a delayed message which cancel the AsyncTask if the background codes running too long time.

Codes in Github.