diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/base/BaseLangDoc.java b/src/main/java/io/github/linwancen/plugin/show/lang/base/BaseLangDoc.java
index 3400652..c36681e 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/base/BaseLangDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/base/BaseLangDoc.java
@@ -181,25 +181,25 @@ public abstract class BaseLangDoc extends EditorLinePainter {
      * static! byte to src, by language
      */
     public static @Nullable <T extends SettingsInfo> String resolveDoc(@NotNull T info,
-                                                                       @NotNull PsiElement psiElement) {
+                                                                       @NotNull PsiElement resolve) {
         try {
-            if (!psiElement.isValid()) {
+            if (!resolve.isValid()) {
                 return null;
             }
             // byte to src
-            PsiElement navElement = psiElement.getNavigationElement();
+            PsiElement navElement = resolve.getNavigationElement();
             if (navElement != null) {
-                psiElement = navElement;
+                resolve = navElement;
             }
         } catch (Throwable ignore) {
             // ignore
         }
         // support like java <-> kotlin
-        @Nullable BaseLangDoc langDoc = PsiElementTo.findLangDoc(psiElement);
+        @Nullable BaseLangDoc langDoc = PsiElementTo.findLangDoc(resolve);
         if (langDoc == null) {
             return null;
         }
-        return langDoc.resolveDocPrint(info, psiElement);
+        return langDoc.resolveDocPrint(info, resolve);
     }
 
     /**
diff --git a/src/main/java/io/github/linwancen/plugin/show/tree/first/FirstDoc.java b/src/main/java/io/github/linwancen/plugin/show/tree/first/FirstDoc.java
index 6d29b96..7102e62 100644
--- a/src/main/java/io/github/linwancen/plugin/show/tree/first/FirstDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/tree/first/FirstDoc.java
@@ -22,7 +22,7 @@ public class FirstDoc {
     private FirstDoc() {}
 
     @Nullable
-    public static String firstDoc(ProjectViewNode<?> node, @NotNull SettingsInfo info) {
+    public static String firstDoc(@NotNull ProjectViewNode<?> node, @NotNull SettingsInfo info) {
         if (!info.appSettings.treeFirst) {
             return null;
         }
@@ -30,7 +30,7 @@ public class FirstDoc {
         if (virtualFile == null || !virtualFile.isValid() || virtualFile.isDirectory()) {
             return null;
         }
-        Project project = node.getProject();
+        @Nullable Project project = node.getProject();
         if (project == null) {
             return null;
         }
@@ -68,15 +68,15 @@ public class FirstDoc {
         if (doc.contains("opyright")) {
             return null;
         }
-        String cutDoc = DocFilter.cutDoc(doc, info, true);
+        @NotNull String cutDoc = DocFilter.cutDoc(doc, info, true);
         FirstDocToDirCache.indexDocToDirDoc(virtualFile, cutDoc);
         return cutDoc;
     }
 
     private static final Pattern COMMENT_PATTERN = Pattern.compile("<!--|/\\*|//|#(?!!)");
     private static boolean notDoc(@NotNull PsiElement psiElement) {
-        String text = PsiUnSaveUtils.getText(psiElement);
-        Matcher matcher = COMMENT_PATTERN.matcher(text);
+        @NotNull String text = PsiUnSaveUtils.getText(psiElement);
+        @NotNull Matcher matcher = COMMENT_PATTERN.matcher(text);
         return !matcher.find();
     }
 }