Fix PackageDeclaration check for files with comments only. #1149

src/main/java/com/puppycrawl/tools/checkstyle/checks/coding/PackageDeclarationCheck.java

@@ -39,6 +39,9 @@ public final class PackageDeclarationCheck extends Check {
      */
     public static final String MSG_KEY = "missing.package.declaration";
 
+    /** Line number used to log violation when no AST nodes are present in file. */
+    private static final int DEFAULT_LINE_NUMBER = 1;
+
     /** is package defined. */
     private boolean defined;
 
@@ -65,7 +68,11 @@ public final class PackageDeclarationCheck extends Check {
     @Override
     public void finishTree(DetailAST ast) {
         if (!defined) {
-            log(ast.getLineNo(), MSG_KEY);
+            int lineNumber = DEFAULT_LINE_NUMBER;
+            if (ast != null) {
+                lineNumber = ast.getLineNo();
+            }
+            log(lineNumber, MSG_KEY);
         }
     }
 

src/test/java/com/puppycrawl/tools/checkstyle/api/DetailASTTest.java

@@ -90,7 +90,9 @@ public class DetailASTTest {
                            System.getProperty("file.encoding", "UTF-8"));
         final FileContents contents = new FileContents(text);
         final DetailAST rootAST = TreeWalker.parse(contents);
-        checkTree(rootAST, null, null, filename, rootAST);
+        if (rootAST != null) {
+            checkTree(rootAST, null, null, filename, rootAST);
+        }
     }
 
     private void checkTree(final DetailAST node,

src/test/java/com/puppycrawl/tools/checkstyle/checks/coding/PackageDeclarationCheckTest.java

@@ -38,4 +38,15 @@ public class PackageDeclarationCheckTest extends BaseCheckTestSupport {
         verify(checkConfig, new File("src/test/resources-noncompilable/com/puppycrawl/tools/"
                 + "checkstyle/coding/InputNoPackage.java").getCanonicalPath(), expected);
     }
+
+    @Test
+    public void testOnFileWithCommentOnly() throws Exception {
+        DefaultConfiguration checkConfig = createCheckConfig(PackageDeclarationCheck.class);
+
+        String[] expected = {
+            "1: " + getCheckMessage(MSG_KEY),
+        };
+
+        verify(checkConfig, getPath("InputWithCommentOnly.java"), expected);
+    }
 }

src/test/resources/com/puppycrawl/tools/checkstyle/InputWithCommentOnly.java

@@ -0,0 +1 @@
+/* Comment only */