[#1870] Bugfix: prevent StringIndexOutOfBoundsException in usage he…

…lp when subcommand has many long aliases

Closes #1870

RELEASE-NOTES.md

@@ -25,6 +25,7 @@ Artifacts in this release are signed by Remko Popma (6601 E5C0 8DCC BB96).
 * [#1886][#1896] Bugfix: AsciiDoc generator now correctly outputs options even if all options are in ArgGroups. Thanks to [Ruud Senden](https://github.com/rsenden) for the discussion and the pull request.
 * [#1878][#1876] Bugfix: Annotation processor now avoids loading resource bundles at compile time. Thanks to [Ruud Senden](https://github.com/rsenden) for the discussion and the pull request.
 * [#1911] Avoid using boxed boolean in `CommandLine.Interpreter.applyValueToSingleValuedField`. Thanks to [Jiehong](https://github.com/Jiehong) for the pull request.
+* [#1870] Bugfix: `StringIndexOutOfBoundsException` in usage help when command has too many (and long) aliases. Thanks to [Martin](https://github.com/martlin2cz) for raising this.ji
 * [#1930] Bugfix: Ensure tests pass in environments for Java 5-18.
 * [#1881] DOC: Many documentation improvements. Thanks to [Andreas Deininger](https://github.com/deining) for the pull request.
 * [#1855][#1857] DOC: Add new user manual section called [Rare Use Cases](https://picocli.info/#_rare_use_cases) detailing `System.exit` usage. Thanks to [Tadaya Tsuyukubo](https://github.com/ttddyy) for the pull request.

src/main/java/picocli/CommandLine.java

@@ -16340,7 +16340,8 @@ public String commandList() {
          * @since 4.4 */
         public String commandList(Map<String, Help> subcommands) {
             if (subcommands.isEmpty()) { return ""; }
-            int commandLength = maxLength(subcommands.keySet());
+            int maxCommandLength = width() / 2;
+            int commandLength = Math.min(maxLength(subcommands.keySet()), maxCommandLength);
             Help.TextTable textTable = Help.TextTable.forColumns(colorScheme().ansi(),
                     new Help.Column(commandLength + 2, 2, Help.Column.Overflow.SPAN),
                     new Help.Column(width() - (commandLength + 2), 2, Help.Column.Overflow.WRAP));

src/test/java/picocli/HelpSubCommandTest.java

@@ -14,6 +14,7 @@
 import java.io.StringWriter;
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.List;
 
 import static java.lang.String.format;
 import static org.junit.Assert.*;
@@ -501,4 +502,32 @@ public void testHelpAllSubcommands() {
         assertEquals(1, help.subcommands().size());
         assertEquals(new HashSet<String>(Arrays.asList("foo")), help.subcommands().keySet());
     }
+
+    @Command(name = "import-from-excel",
+        aliases = { "import-from-xls", "import-from-xlsx", "import-from-csv", "import-from-txt" },
+        description = "Imports the data from various excel files (xls, xlsx, csv or even txt).")
+    static class ImportCommand implements Runnable {
+
+        @Parameters(arity = "1..*")
+        public List<String> files;
+
+        @Override
+        public void run() {
+            System.out.println("ImportCommand.run()");
+        }
+    }
+    @Test
+    public void testIssue1870StringIndexOutOfBounds() {
+        @Command(name = "top", subcommands = ImportCommand.class) class Top { }
+        String actual = usageString(new CommandLine(new Top()), Help.Ansi.OFF);
+        String expected = String.format("" +
+            "Usage: top [COMMAND]%n" +
+            "Commands:%n" +
+            "  import-from-excel, import-from-xls, import-from-xlsx, import-from-csv,%n" +
+            "    import-from-txt%n" +
+            "                                            Imports the data from various excel%n" +
+            "                                              files (xls, xlsx, csv or even%n" +
+            "                                              txt).%n");
+        assertEquals(expected, actual);
+    }
 }