How to use Thread Dump in java

public class JStack { public static void main(String[] args) throws Exception { ... String pid = args[optionCount]; String params[]; if (locks) { params = new String[] { "-l" }; } else { params = new String[0]; } runThreadDump(pid, params); ... } // Attach to pid and perform a thread dump private static void runThreadDump(String pid, String args[]) throws Exception { VirtualMachine vm = null; try { vm = VirtualMachine.attach(pid); } catch (Exception x) { ... } // Cast to HotSpotVirtualMachine as this is implementation specific // method. InputStream in = ((HotSpotVirtualMachine) vm) .remoteDataDump((Object[]) args); // read to EOF and just print output byte b[] = new byte[256]; int n; do { n = in.read(b); if (n > 0) { String s = new String(b, 0, n, "UTF-8"); System.out.print(s); } } while (n > 0); in.close(); vm.detach(); }