[#805] add example for alphabetically sorting subcommands by subclass…

…ing `Help`

picocli-examples/src/main/java/picocli/examples/customhelp/AlphabeticSubcommands.java

@@ -0,0 +1,63 @@
+package picocli.examples.customhelp;
+
+import picocli.CommandLine;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.Help;
+import picocli.CommandLine.HelpCommand;
+import picocli.CommandLine.IHelpFactory;
+import picocli.CommandLine.Model.CommandSpec;
+import picocli.CommandLine.Spec;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * This class has subcommands that are not declared alphabetically.
+ * We want the help for this class to show the subcommands alphabetically.
+ */
+@Command(name = "alphabetic",
+        description = "a command that shows subcommands sorted alphabetically",
+        subcommands = {Charlie.class, Bravo.class, Alpha.class, HelpCommand.class})
+public class AlphabeticSubcommands implements Runnable {
+
+    @Spec CommandSpec spec;
+
+    @Override
+    public void run() {
+        spec.commandLine().usage(System.out);
+    }
+
+    public static void main(String[] args) {
+        CommandLine commandLine = new CommandLine(new AlphabeticSubcommands());
+        commandLine.setHelpFactory(new IHelpFactory() {
+            @Override
+            public Help create(CommandSpec commandSpec, Help.ColorScheme colorScheme) {
+                return new Help(commandSpec, colorScheme) {
+                    /**
+                     * Returns a sorted map of the subcommands.
+                     */
+                    @Override
+                    protected Map<String, Help> subcommands() {
+                        return new TreeMap<>(super.subcommands());
+                    }
+                };
+            }
+        });
+        commandLine.execute(args);
+    }
+}
+
+@Command(name = "charlie", description = "my name starts with C")
+class Charlie implements Runnable {
+    public void run() {}
+}
+
+@Command(name = "bravo", description = "my name starts with B")
+class Bravo implements Runnable {
+    public void run() {}
+}
+
+@Command(name = "alpha", description = "my name starts with A")
+class Alpha implements Runnable {
+    public void run() {}
+}