#156 improved user manual full application example

src/test/java/picocli/Demo.java

@@ -667,6 +667,9 @@ public void testUsageSubCommandCommit() {
  @Command(name = "checksum", description = "Prints the checksum (MD5 by default) of a file to STDOUT.")
  class CheckSum implements Callable<Void> {
 
+ @Option(names = {"-h", "--help"}, usageHelp = true, description = "Show this help message and exit.")
+ private boolean helpRequested;
+
  @Option(names = {"-a", "--algorithm"}, description = "MD5, SHA-1, SHA-256, ...")
  private String algorithm = "MD5";
 
@@ -679,6 +682,10 @@ public static void main(String[] args) throws Exception {
 
  @Override
  public Void call() throws Exception {
+ if (helpRequested) {
+ CommandLine.usage(this, System.err);
+ return null;
+ }
  byte[] digest = MessageDigest.getInstance(algorithm).digest(readBytes(file));
  print(digest, System.out);
  return null;