Cleaned up InvalidUsageException and CommandException to be less confusing.

src/main/java/com/sk89q/minecraft/util/commands/CommandException.java

@@ -19,10 +19,13 @@
 
 package com.sk89q.minecraft.util.commands;
 
+import javax.annotation.Nullable;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.ListIterator;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 public class CommandException extends Exception {
     
     private static final long serialVersionUID = 870638193072101739L;
@@ -48,7 +51,16 @@ public class CommandException extends Exception {
         commandStack.add(name);
     }
 
-    public String toStackString(String prefix, String spacedSuffix) {
+    /**
+     * Gets the command that was called, which will include the sub-command
+     * (i.e. "/br sphere").
+     *
+     * @param prefix the command shebang character (such as "/") -- may be empty
+     * @param spacedSuffix a suffix to put at the end (optional) -- may be null
+     * @return the command that was used
+     */
+    public String getCommandUsed(String prefix, @Nullable String spacedSuffix) {
+        checkNotNull(prefix);
         StringBuilder builder = new StringBuilder();
         if (prefix != null) {
             builder.append(prefix);

src/main/java/com/sk89q/worldedit/extension/platform/CommandManager.java

@@ -222,8 +222,8 @@ public final class CommandManager {
         } catch (CommandPermissionsException e) {
             actor.printError("You don't have permission to do this.");
         } catch (InvalidUsageException e) {
-            if (e.isFullUsageSuggested()) {
-                actor.printRaw(ColorCodeBuilder.asColorCodes(new CommandUsageBox(e.getCommand(), e.toStackString("/", ""), locals)));
+            if (e.isFullHelpSuggested()) {
+                actor.printRaw(ColorCodeBuilder.asColorCodes(new CommandUsageBox(e.getCommand(), e.getCommandUsed("/", ""), locals)));
                 String message = e.getMessage();
                 if (message != null) {
                     actor.printError(message);
@@ -231,7 +231,7 @@ public final class CommandManager {
             } else {
                 String message = e.getMessage();
                 actor.printError(message != null ? message : "The command was not used properly (no more help available).");
-                actor.printError(e.getUsage("/"));
+                actor.printError(e.getSimpleUsageString("/"));
             }
         } catch (WrappedCommandException e) {
             Throwable t = e.getCause();

src/main/java/com/sk89q/worldedit/util/command/InvalidUsageException.java

@@ -21,38 +21,79 @@ package com.sk89q.worldedit.util.command;
 
 import com.sk89q.minecraft.util.commands.CommandException;
 
+import javax.annotation.Nullable;
+
 import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Thrown when a command is not used properly.
+ * </p>
+ * When handling this exception, print the error message if it is not null.
+ * Print a one line help instruction unless {@link #isFullHelpSuggested()}
+ * is true, which, in that case, the full help of the command should be shown.
+ * </p>
+ * If no error message is set and full help is not to be shown, then a generic
+ * "you used this command incorrectly" message should be shown.
  */
 public class InvalidUsageException extends CommandException {
 
     private static final long serialVersionUID = -3222004168669490390L;
     private final CommandCallable command;
-    private final boolean fullUsageSuggested;
+    private final boolean fullHelpSuggested;
 
+    /**
+     * Create a new instance with no error message and with no suggestion
+     * that full and complete help for the command should be shown. This will
+     * result in a generic error message.
+     *
+     * @param command the command
+     */
     public InvalidUsageException(CommandCallable command) {
         this(null, command);
     }
 
-    public InvalidUsageException(String message, CommandCallable command) {
+    /**
+     * Create a new instance with a message and with no suggestion
+     * that full and complete help for the command should be shown.
+     *
+     * @param message the message
+     * @param command the command
+     */
+    public InvalidUsageException(@Nullable String message, CommandCallable command) {
         this(message, command, false);
     }
 
-    public InvalidUsageException(String message, CommandCallable command, boolean fullUsageSuggested) {
+    /**
+     * Create a new instance with a message.
+     *
+     * @param message the message
+     * @param command the command
+     * @param fullHelpSuggested true if the full help for the command should be shown
+     */
+    public InvalidUsageException(@Nullable String message, CommandCallable command, boolean fullHelpSuggested) {
         super(message);
         checkNotNull(command);
         this.command = command;
-        this.fullUsageSuggested = fullUsageSuggested;
+        this.fullHelpSuggested = fullHelpSuggested;
     }
 
+    /**
+     * Get the command.
+     *
+     * @return the command
+     */
     public CommandCallable getCommand() {
         return command;
     }
 
-    public String getUsage(String prefix) {
-        return toStackString(prefix, command.getDescription().getUsage());
+    /**
+     * Get a simple usage string.
+     *
+     * @param prefix the command shebang (such as "/") -- may be blank
+     * @return a usage string
+     */
+    public String getSimpleUsageString(String prefix) {
+        return getCommandUsed(prefix, command.getDescription().getUsage());
     }
 
     /**
@@ -60,7 +101,7 @@ public class InvalidUsageException extends CommandException {
      *
      * @return show full usage
      */
-    public boolean isFullUsageSuggested() {
-        return fullUsageSuggested;
+    public boolean isFullHelpSuggested() {
+        return fullHelpSuggested;
     }
 }