8352645: Add tool support to check order of includes

test/hotspot/jtreg/sources/SortIncludes.java

@@ -33,7 +33,9 @@
 import java.util.TreeSet;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
+/// See [#main].
 public class SortIncludes {
     private static final String INCLUDE_LINE = "^ *# *include *(<[^>]+>|\"[^\"]+\") *$\\n";
     private static final String BLANK_LINE = "^$\\n";
@@ -191,6 +193,12 @@ public static class UnsortedIncludesException extends Exception {
         public UnsortedIncludesException(List<Path> files) {
             this.files = files;
         }
+
+        @Override
+        public String getMessage() {
+            String unsorted = files.stream().map(Path::toString).collect(Collectors.joining(System.lineSeparator()));
+            return String.format("%d files with unsorted headers found:%n%s", files.size(), unsorted);
+        }
     }
 
     /// Processes C++ files to check if their include statements are sorted.

test/hotspot/jtreg/sources/TestIncludesAreSorted.java

@@ -33,7 +33,6 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class TestIncludesAreSorted {
@@ -75,10 +74,7 @@ public static void main(String[] ignore) throws IOException {
         try {
             SortIncludes.main(args);
         } catch (SortIncludes.UnsortedIncludesException e) {
-            String unsorted = e.files.stream().map(Path::toString).collect(Collectors.joining(System.lineSeparator()));
             String msg = String.format("""
-                            %d files with unsorted headers found:
-
                             %s
 
                             This should be fixable by running:
@@ -104,7 +100,7 @@ public static void main(String[] ignore) throws IOException {
                             #include "b.hpp"
 
                             """,
-                    e.files.size(), unsorted,
+                    e.getMessage(),
                     testSrcDir.resolve(SortIncludes.class.getSimpleName()),
                     String.join(" ", args));
             throw new RuntimeException(msg);