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.tool; 27 28 import java.io.PrintStream; 29 import java.util.Arrays; 30 import java.util.Collections; 31 import java.util.Deque; 32 import java.util.List; 33 34 final class Help extends Command { 35 36 @Override 37 public String getName() { 38 return "help"; 39 } 40 41 @Override 42 public List<String> getOptionSyntax() { 43 return Collections.singletonList("[<command>]"); 44 } 45 46 protected List<String> getAliases() { 47 return Arrays.asList("--help", "-h", "-?"); 48 } 49 50 @Override 51 public void displayOptionUsage(PrintStream stream) { 52 println(" <command> The name of the command to get help for"); 53 } 54 55 @Override 56 public String getDescription() { 57 return "Display all available commands, or help about a specific command"; 58 } 59 60 @Override 61 public void execute(Deque<String> options) throws UserSyntaxException, UserDataException { 62 if (options.isEmpty()) { 63 Command.displayHelp(); 64 return; 65 } 66 ensureMaxArgumentCount(options, 1); 67 String commandName = options.remove(); 68 Command c = Command.valueOf(commandName); 69 if (c == null) { 70 throw new UserDataException("unknown command '" + commandName + "'"); 71 } 72 println(c.getTitle()); 73 println(); 74 c.displayUsage(System.out); 75 } 76 }