1 /*

     2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.jfr.internal.cmd;

    27 

    28 import java.util.Deque;

    29 

    30 final class HelpCommand extends Command {

    31 

    32     @Override

    33     public String getOptionSyntax() {

    34         return "[<command>]";

    35     }

    36 

    37     @Override

    38     public void displayOptionUsage() {

    39         println("  <command>   The name of the command to get help for");

    40         println();

    41         Command.displayAvailableCommands();

    42     }

    43 

    44     @Override

    45     public String getName() {

    46         return "help";

    47     }

    48 

    49     @Override

    50     public String getDescription() {

    51         return "Display help about a command";

    52     }

    53 

    54     @Override

    55     public void execute(Deque<String> options) {

    56         if (options.isEmpty()) {

    57             displayUsage();

    58         } else {

    59             ensureMaxArgumentCount(options, 1);

    60             String commandName = options.remove();

    61             Command c = Command.valueOf(commandName);

    62             if (c == null) {

    63                 userFailed("Unknown command " + commandName);

    64             }

    65             c.displayUsage();

    66         }

    67     }

    68 }