diff --git a/src/main/idea/io/github/linwancen/plugin/show/java/MavenLangDoc.java b/src/main/idea/io/github/linwancen/plugin/show/java/MavenLangDoc.java
index 99838d6..2ccc9ac 100644
--- a/src/main/idea/io/github/linwancen/plugin/show/java/MavenLangDoc.java
+++ b/src/main/idea/io/github/linwancen/plugin/show/java/MavenLangDoc.java
@@ -16,7 +16,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class MavenLangDoc extends XmlLangDoc {
-    Pattern PARAM_PATTERN = Pattern.compile("\\$\\{[^}]++}");
+    @NotNull Pattern PARAM_PATTERN = Pattern.compile("\\$\\{[^}]++}");
 
     @Nullable
     @Override
@@ -25,12 +25,12 @@ public class MavenLangDoc extends XmlLangDoc {
         if (!"pom.xml".equals(info.file.getName()) || !info.text.contains("$")) {
             return null;
         }
-        MavenDomProjectModel mdm = MavenDomUtil.getMavenDomModel(element.getContainingFile(), MavenDomProjectModel.class);
+        @Nullable MavenDomProjectModel mdm = MavenDomUtil.getMavenDomModel(element.getContainingFile(), MavenDomProjectModel.class);
         if (mdm == null) {
             return null;
         }
-        List<String> list = new ArrayList<>();
-        Matcher m = PARAM_PATTERN.matcher(info.text);
+        @NotNull List<String> list = new ArrayList<>();
+        @NotNull Matcher m = PARAM_PATTERN.matcher(info.text);
         while (m.find()) {
             String s = m.group();
             String v;
diff --git a/src/main/idea/io/github/linwancen/plugin/show/java/ScalaLangDoc.java b/src/main/idea/io/github/linwancen/plugin/show/java/ScalaLangDoc.java
index 4a2a809..2d39608 100644
--- a/src/main/idea/io/github/linwancen/plugin/show/java/ScalaLangDoc.java
+++ b/src/main/idea/io/github/linwancen/plugin/show/java/ScalaLangDoc.java
@@ -73,7 +73,7 @@ public class ScalaLangDoc extends JavaLangDoc {
         for (@NotNull PsiDocTag tag : tags) {
             if (tag instanceof ScDocTag) {
                 @NotNull ScDocTag scDocTag = (ScDocTag) tag;
-                String doc = PsiUnSaveUtils.getText(scDocTag);
+                @NotNull String doc = PsiUnSaveUtils.getText(scDocTag);
                 doc = doc.replace(key, "");
                 DocFilter.addHtml(tagStrBuilder, doc);
             }
diff --git a/src/main/idea/io/github/linwancen/plugin/show/java/doc/AnnoDocJava.java b/src/main/idea/io/github/linwancen/plugin/show/java/doc/AnnoDocJava.java
index b6cc60d..22e8069 100644
--- a/src/main/idea/io/github/linwancen/plugin/show/java/doc/AnnoDocJava.java
+++ b/src/main/idea/io/github/linwancen/plugin/show/java/doc/AnnoDocJava.java
@@ -17,6 +17,7 @@ import org.jetbrains.annotations.Nullable;
 
 public class AnnoDocJava extends BaseAnnoDoc<PsiJvmModifiersOwner> {
 
+    @NotNull
     public static AnnoDocJava INSTANCE = new AnnoDocJava();
 
     private AnnoDocJava() {}
@@ -76,8 +77,8 @@ public class AnnoDocJava extends BaseAnnoDoc<PsiJvmModifiersOwner> {
         @NotNull Project project = value.getProject();
         @NotNull PsiConstantEvaluationHelper helper = JavaPsiFacade.getInstance(project).getConstantEvaluationHelper();
         if (value instanceof PsiArrayInitializerMemberValue) {
-            PsiAnnotationMemberValue[] initializers = ((PsiArrayInitializerMemberValue) value).getInitializers();
-            StringBuilder sb = new StringBuilder();
+            @NotNull PsiAnnotationMemberValue[] initializers = ((PsiArrayInitializerMemberValue) value).getInitializers();
+            @NotNull StringBuilder sb = new StringBuilder();
             for (PsiAnnotationMemberValue initializer : initializers) {
                 try {
                     sb.append(helper.computeConstantExpression(initializer)).append("  ");
diff --git a/src/main/idea/io/github/linwancen/plugin/show/java/kt/AnnoDocKt.java b/src/main/idea/io/github/linwancen/plugin/show/java/kt/AnnoDocKt.java
index f7d2fd6..294b32d 100644
--- a/src/main/idea/io/github/linwancen/plugin/show/java/kt/AnnoDocKt.java
+++ b/src/main/idea/io/github/linwancen/plugin/show/java/kt/AnnoDocKt.java
@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.psi.ValueArgumentName;
 
 public class AnnoDocKt extends BaseAnnoDoc<KtAnnotated> {
 
+    @NotNull
     public static AnnoDocKt INSTANCE = new AnnoDocKt();
 
     private AnnoDocKt() {}
@@ -24,8 +25,8 @@ public class AnnoDocKt extends BaseAnnoDoc<KtAnnotated> {
     @Nullable
     protected String annoDocMatch(@NotNull KtAnnotated owner, @NotNull String[] arr) {
         if (typeMatch(owner, arr[0])) {
-            for (KtAnnotationEntry entry : owner.getAnnotationEntries()) {
-                String s = annoDocName(entry, arr);
+            for (@NotNull KtAnnotationEntry entry : owner.getAnnotationEntries()) {
+                @Nullable String s = annoDocName(entry, arr);
                 if (s != null) {
                     return s;
                 }
@@ -52,11 +53,11 @@ public class AnnoDocKt extends BaseAnnoDoc<KtAnnotated> {
 
     @Nullable
     private static String annoDocName(@NotNull KtAnnotationEntry entry, @NotNull String[] arr) {
-        Name shortName = entry.getShortName();
+        @Nullable Name shortName = entry.getShortName();
         if (shortName == null) {
             return null;
         }
-        String name = shortName.asString();
+        @NotNull String name = shortName.asString();
         String annoName = arr[1];
         int i = annoName.lastIndexOf('.');
         if (i > 0) {
@@ -65,15 +66,15 @@ public class AnnoDocKt extends BaseAnnoDoc<KtAnnotated> {
         if (!annoName.equals(name)) {
             return null;
         }
-        for (ValueArgument argument : entry.getValueArguments()) {
-            ValueArgumentName argumentName = argument.getArgumentName();
-            String method = argumentName == null ? "value" : argumentName.getAsName().asString();
+        for (@NotNull ValueArgument argument : entry.getValueArguments()) {
+            @Nullable ValueArgumentName argumentName = argument.getArgumentName();
+            @NotNull String method = argumentName == null ? "value" : argumentName.getAsName().asString();
             if (arr[2].equals(method)) {
-                KtExpression expression = argument.getArgumentExpression();
+                @Nullable KtExpression expression = argument.getArgumentExpression();
                 if (expression instanceof KtStringTemplateExpression) {
-                    String text = PsiUnSaveUtils.getText(expression);
+                    @NotNull String text = PsiUnSaveUtils.getText(expression);
                     if (text.length() >= 2) {
-                        String s = text.substring(1, text.length() - 1);
+                        @NotNull String s = text.substring(1, text.length() - 1);
                         if (!s.isEmpty()) {
                             return s;
                         }
diff --git a/src/main/idea/io/github/linwancen/plugin/show/java/line/SkipUtils.java b/src/main/idea/io/github/linwancen/plugin/show/java/line/SkipUtils.java
index 95f3f7c..7a0326c 100644
--- a/src/main/idea/io/github/linwancen/plugin/show/java/line/SkipUtils.java
+++ b/src/main/idea/io/github/linwancen/plugin/show/java/line/SkipUtils.java
@@ -61,7 +61,7 @@ public class SkipUtils {
         if (info.appSettings.skipBlank && isBlank(doc)) {
             return null;
         }
-        String text = PsiUnSaveUtils.getText(doc);
+        @NotNull String text = PsiUnSaveUtils.getText(doc);
         boolean skip = DocSkip.skipDoc(info, text);
         return skip ? null : doc;
     }
@@ -69,7 +69,7 @@ public class SkipUtils {
     private static boolean isBlank(@NotNull PsiDocComment doc) {
         @NotNull PsiElement[] elements = doc.getDescriptionElements();
         for (@NotNull PsiElement element : elements) {
-            String text = PsiUnSaveUtils.getText(element);
+            @NotNull String text = PsiUnSaveUtils.getText(element);
             if (StringUtils.isNotBlank(text)) {
                 return false;
             }
diff --git a/src/main/java/io/github/linwancen/plugin/show/bean/FileInfo.java b/src/main/java/io/github/linwancen/plugin/show/bean/FileInfo.java
index 4243ee3..4cb20ef 100644
--- a/src/main/java/io/github/linwancen/plugin/show/bean/FileInfo.java
+++ b/src/main/java/io/github/linwancen/plugin/show/bean/FileInfo.java
@@ -56,7 +56,7 @@ public class FileInfo extends SettingsInfo {
         return new FileInfo(file, document, project, FuncEnum.LINE);
     }
 
-    public String getText(PsiElement element) {
+    public String getText(@NotNull PsiElement element) {
         try {
             TextRange range = element.getTextRange();
             int startOffset = range.getStartOffset();
diff --git a/src/main/java/io/github/linwancen/plugin/show/cache/LineEndCacheUtils.java b/src/main/java/io/github/linwancen/plugin/show/cache/LineEndCacheUtils.java
index ab35ec3..0bb52b6 100644
--- a/src/main/java/io/github/linwancen/plugin/show/cache/LineEndCacheUtils.java
+++ b/src/main/java/io/github/linwancen/plugin/show/cache/LineEndCacheUtils.java
@@ -65,7 +65,7 @@ public class LineEndCacheUtils {
         }
     }
 
-    private static void cacheUpdate(Project project, Map<VirtualFile, Map<Integer, LineEndCache>> fileMap) {
+    private static void cacheUpdate(@NotNull Project project, @NotNull Map<VirtualFile, Map<Integer, LineEndCache>> fileMap) {
         try {
             if (project.isDisposed() || DumbService.isDumb(project)) {
                 return;
diff --git a/src/main/java/io/github/linwancen/plugin/show/cache/TreeCacheUtils.java b/src/main/java/io/github/linwancen/plugin/show/cache/TreeCacheUtils.java
index 89b31ed..05e7165 100644
--- a/src/main/java/io/github/linwancen/plugin/show/cache/TreeCacheUtils.java
+++ b/src/main/java/io/github/linwancen/plugin/show/cache/TreeCacheUtils.java
@@ -40,7 +40,7 @@ public class TreeCacheUtils {
         }
     }
 
-    private static void cacheUpdate(Project project, Map<ProjectViewNode<?>, TreeCache> nodeCache) {
+    private static void cacheUpdate(@NotNull Project project, @NotNull Map<ProjectViewNode<?>, TreeCache> nodeCache) {
         try {
             nodeCache.forEach((node, treeCache) -> {
                 if (treeCache.needUpdate) {
diff --git a/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlCache.java b/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlCache.java
index 2157045..3f204f3 100644
--- a/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlCache.java
+++ b/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlCache.java
@@ -34,7 +34,7 @@ public class SqlCache extends FileLoader {
     @Nullable
     @Override
     public String treeDoc(@NotNull VirtualFile virtualFile) {
-        String name = virtualFile.getNameWithoutExtension();
+        @NotNull String name = virtualFile.getNameWithoutExtension();
         return TABLE_DOC_CACHE.get(name);
     }
 
@@ -52,8 +52,8 @@ public class SqlCache extends FileLoader {
 
     @Override
     public void loadAllImpl(@NotNull Project project) {
-        GlobalSettingsState g = GlobalSettingsState.getInstance();
-        ProjectSettingsState p = ProjectSettingsState.getInstance(project);
+        @NotNull GlobalSettingsState g = GlobalSettingsState.getInstance();
+        @NotNull ProjectSettingsState p = ProjectSettingsState.getInstance(project);
         if (!g.sqlSplitEffect && !p.sqlSplitEffect) {
             return;
         }
@@ -74,18 +74,18 @@ public class SqlCache extends FileLoader {
 
     @Override
     public void loadFileImpl(@NotNull VirtualFile file, @Nullable Project project) {
-        String code = PsiUnSaveUtils.fileText(project, file);
+        @Nullable String code = PsiUnSaveUtils.fileText(project, file);
         if (code == null) {
             return;
         }
-        GlobalSettingsState g = GlobalSettingsState.getInstance();
+        @NotNull GlobalSettingsState g = GlobalSettingsState.getInstance();
         loadSqlDoc(code, TABLE_DOC_CACHE, g.tableDocEffect, g.tableDoc);
         loadSqlDoc(code, COLUMN_DOC_CACHE, g.columnDocEffect, g.columnDoc);
         loadSqlDoc(code, INDEX_DOC_CACHE, g.indexDocEffect, g.indexDoc);
         if (project == null) {
             return;
         }
-        ProjectSettingsState p = ProjectSettingsState.getInstance(project);
+        @NotNull ProjectSettingsState p = ProjectSettingsState.getInstance(project);
         loadSqlDoc(code, TABLE_DOC_CACHE, p.tableDocEffect, p.tableDoc);
         loadSqlDoc(code, COLUMN_DOC_CACHE, p.columnDocEffect, p.columnDoc);
         loadSqlDoc(code, INDEX_DOC_CACHE, p.indexDocEffect, p.indexDoc);
@@ -94,13 +94,13 @@ public class SqlCache extends FileLoader {
     public static final Pattern KEY_PATTERN = Pattern.compile("`?, *`?");
 
     private static void loadSqlDoc(@NotNull String code, @NotNull Map<String, String> map,
-                                   boolean effect, Map<String, Pattern[]> patternMap) {
+                                   boolean effect, @NotNull Map<String, Pattern[]> patternMap) {
         if (!effect) {
             return;
         }
-        for (Pattern[] patterns : patternMap.values()) {
-            for (Pattern pattern : patterns) {
-                Matcher m = pattern.matcher(code);
+        for (@NotNull Pattern[] patterns : patternMap.values()) {
+            for (@NotNull Pattern pattern : patterns) {
+                @NotNull Matcher m = pattern.matcher(code);
                 while (m.find()) {
                     String key = m.group(1);
                     String comment = m.group(2);
@@ -121,7 +121,7 @@ public class SqlCache extends FileLoader {
 
     private static final Pattern IGNORE_KEY_PATTERN = Pattern.compile("(?i)^(id|name)$");
 
-    private static void putComment(@NotNull Map<String, String> map, @NotNull String k, String comment) {
+    private static void putComment(@NotNull Map<String, String> map, @NotNull String k, @NotNull String comment) {
         if (IGNORE_KEY_PATTERN.matcher(k).find()) {
             return;
         }
diff --git a/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlDoc.java b/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlDoc.java
index 4e7ff8d..d1fb5d5 100644
--- a/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/ext/sql/SqlDoc.java
@@ -12,17 +12,18 @@ public class SqlDoc {
 
     @Nullable
     public static String sqlDoc(@NotNull LineInfo info, @NotNull String code) {
-        String extension = info.file.getExtension();
+        @Nullable String extension = info.file.getExtension();
         if (extension == null) {
             return null;
         }
-        String s = sqlDocState(extension, info.projectSettings, code);
+        @Nullable String s = sqlDocState(extension, info.projectSettings, code);
         if (s != null) {
             return s;
         }
         return sqlDocState(extension, info.globalSettings, code);
     }
 
+    @Nullable
     private static String sqlDocState(@NotNull String extension, @NotNull AbstractSettingsState state,
                                       @NotNull String code) {
         if (!state.sqlSplitEffect) {
@@ -32,7 +33,7 @@ public class SqlDoc {
         if (patterns == null) {
             return null;
         }
-        for (Pattern pattern : patterns) {
+        for (@NotNull Pattern pattern : patterns) {
             return sqlDocPattern(pattern, code);
         }
         return null;
@@ -83,7 +84,8 @@ public class SqlDoc {
         return false;
     }
 
-    private static String indexSymbol(String indexDoc) {
+    @NotNull
+    private static String indexSymbol(@NotNull String indexDoc) {
         switch (indexDoc) {
             case "primary":
             case "PRIMARY":
@@ -110,7 +112,7 @@ public class SqlDoc {
     }
 
     @NotNull
-    private static String unescape(String keyword) {
+    private static String unescape(@NotNull String keyword) {
         // &gt;|&lt;|&amp;|&quot;|&apos;
         switch (keyword) {
             case "&gt;":
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/PhpLangDoc.java b/src/main/java/io/github/linwancen/plugin/show/lang/PhpLangDoc.java
index 99136ef..4f9a646 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/PhpLangDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/PhpLangDoc.java
@@ -48,7 +48,7 @@ public class PhpLangDoc extends BaseTagLangDoc<PhpDocComment> {
                 for (PsiElement child : children) {
                     @Nullable PsiComment comment = PsiTreeUtil.getChildOfType(child, PsiComment.class);
                     if (comment != null) {
-                        String text = PsiUnSaveUtils.getText(comment);
+                        @NotNull String text = PsiUnSaveUtils.getText(comment);
                         return DocFilter.cutDoc(text, info, true);
                     }
                 }
@@ -75,7 +75,7 @@ public class PhpLangDoc extends BaseTagLangDoc<PhpDocComment> {
     @NotNull
     @Override
     protected <T extends SettingsInfo> String descDoc(@NotNull T info, @NotNull PhpDocComment phpDocComment) {
-        String text = PsiUnSaveUtils.getText(phpDocComment);
+        @NotNull String text = PsiUnSaveUtils.getText(phpDocComment);
         return DocFilter.cutDoc(text, info, true);
     }
 
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/XmlLangDoc.java b/src/main/java/io/github/linwancen/plugin/show/lang/XmlLangDoc.java
index 5f3d59f..45e2a86 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/XmlLangDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/XmlLangDoc.java
@@ -48,9 +48,9 @@ public class XmlLangDoc extends BaseLangDoc {
         if (viewProvider == null) {
             return null;
         }
-        PsiElement psiElement = viewProvider.findElementAt(0);
+        @Nullable PsiElement psiElement = viewProvider.findElementAt(0);
         if (psiElement == null || !"<!--".equals(PsiUnSaveUtils.getText(psiElement))) {
-            Document document = viewProvider.getDocument();
+            @Nullable Document document = viewProvider.getDocument();
             if (document == null) {
                 return null;
             }
@@ -70,11 +70,11 @@ public class XmlLangDoc extends BaseLangDoc {
         if (!(parent instanceof PsiComment)) {
             return null;
         }
-        PsiElement[] children = parent.getChildren();
+        @NotNull PsiElement[] children = parent.getChildren();
         if (children.length < 2) {
             return null;
         }
-        String doc = PsiUnSaveUtils.getText(children[1]);
+        @Nullable String doc = PsiUnSaveUtils.getText(children[1]);
         // Copyright or copyright
         //noinspection SpellCheckingInspection
         if (doc == null || doc.contains("opyright")) {
@@ -87,10 +87,10 @@ public class XmlLangDoc extends BaseLangDoc {
     @Nullable
     @Override
     public String findRefDoc(@NotNull LineInfo info, @NotNull FileViewProvider viewProvider, @NotNull PsiElement element) {
-        ExtensionPointName<XmlLangDoc> epn = ExtensionPointName.create("io.github.linwancen.show-comment.xmlLangDoc");
-        List<XmlLangDoc> extensionList = epn.getExtensionList();
-        for (XmlLangDoc xmlLangDoc : extensionList) {
-            String doc = xmlLangDoc.findRefDoc(info, viewProvider, element);
+        @NotNull ExtensionPointName<XmlLangDoc> epn = ExtensionPointName.create("io.github.linwancen.show-comment.xmlLangDoc");
+        @NotNull List<XmlLangDoc> extensionList = epn.getExtensionList();
+        for (@NotNull XmlLangDoc xmlLangDoc : extensionList) {
+            @Nullable String doc = xmlLangDoc.findRefDoc(info, viewProvider, element);
             if (doc != null && !doc.trim().isEmpty()) {
                 return doc;
             }
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/base/Prev.java b/src/main/java/io/github/linwancen/plugin/show/lang/base/Prev.java
index d8f2772..0829ac0 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/base/Prev.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/base/Prev.java
@@ -62,7 +62,7 @@ public class Prev {
     @Nullable
     private static PsiElement refClassParent(@NotNull PsiElement element,
                                              @NotNull List<Class<? extends PsiElement>> refClass) {
-        String text = PsiUnSaveUtils.getText(element);
+        @NotNull String text = PsiUnSaveUtils.getText(element);
         if (!SYMBOL_PATTERN.matcher(text).find()) {
             return null;
         }
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/base/PsiUnSaveUtils.java b/src/main/java/io/github/linwancen/plugin/show/lang/base/PsiUnSaveUtils.java
index 4de642f..4b8f51f 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/base/PsiUnSaveUtils.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/base/PsiUnSaveUtils.java
@@ -8,12 +8,15 @@ import com.intellij.psi.PsiDocumentManager;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiManager;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 public class PsiUnSaveUtils {
 
-    public static String getText(PsiElement element) {
+    @Contract("!null -> !null")
+    @Nullable
+    public static String getText(@Nullable PsiElement element) {
         try {
             if (element == null) {
                 return null;
@@ -23,7 +26,7 @@ public class PsiUnSaveUtils {
                 return element.getText();
             }
             if (element instanceof PsiFile) {
-                Document document = documentManager.getDocument(((PsiFile) element));
+                @Nullable Document document = documentManager.getDocument(((PsiFile) element));
                 if (document == null) {
                     return element.getText();
                 }
@@ -33,7 +36,7 @@ public class PsiUnSaveUtils {
             if (containingFile == null) {
                 return element.getText();
             }
-            Document document = documentManager.getDocument(containingFile);
+            @Nullable Document document = documentManager.getDocument(containingFile);
             if (document == null) {
                 return element.getText();
             }
@@ -45,14 +48,14 @@ public class PsiUnSaveUtils {
 
     @Nullable
     public static String fileText(@Nullable Project project, @NotNull VirtualFile file) {
-        Document document = FileDocumentManager.getInstance().getDocument(file);
+        @Nullable Document document = FileDocumentManager.getInstance().getDocument(file);
         if (document != null) {
             return document.getText();
         }
         if (project == null) {
             return null;
         }
-        PsiFile psiFile = PsiManager.getInstance(project).findFile(file);
+        @Nullable PsiFile psiFile = PsiManager.getInstance(project).findFile(file);
         if (psiFile != null) {
             return psiFile.getText();
         }
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/base/ResolveDoc.java b/src/main/java/io/github/linwancen/plugin/show/lang/base/ResolveDoc.java
index 57956eb..a6c3786 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/base/ResolveDoc.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/base/ResolveDoc.java
@@ -74,7 +74,7 @@ public class ResolveDoc {
         }
         if (!keywords.isEmpty()) {
             while (psiElement != null) {
-                String text = PsiUnSaveUtils.getText(psiElement);
+                @NotNull String text = PsiUnSaveUtils.getText(psiElement);
                 if (keywords.contains(text)) {
                     psiElement = Prev.prevCompactElement(info, psiElement, document);
                 } else {
@@ -85,7 +85,7 @@ public class ResolveDoc {
         @NotNull StringBuilder sb = new StringBuilder();
         boolean isComment = psiElement instanceof PsiComment;
         while (isComment) {
-            String text = PsiUnSaveUtils.getText(psiElement);
+            @NotNull String text = PsiUnSaveUtils.getText(psiElement);
             int thisStartOffset = psiElement.getTextRange().getStartOffset();
             psiElement = Prev.prevCompactElement(info, psiElement, document);
             isComment = psiElement instanceof PsiComment;
diff --git a/src/main/java/io/github/linwancen/plugin/show/lang/vue/VueRouterCache.java b/src/main/java/io/github/linwancen/plugin/show/lang/vue/VueRouterCache.java
index 73abce4..deeb93e 100644
--- a/src/main/java/io/github/linwancen/plugin/show/lang/vue/VueRouterCache.java
+++ b/src/main/java/io/github/linwancen/plugin/show/lang/vue/VueRouterCache.java
@@ -77,7 +77,7 @@ public class VueRouterCache extends FileLoader {
         if (psiFile == null) {
             return;
         }
-        Collection<JSArrayLiteralExpression> arrays =
+        @NotNull Collection<JSArrayLiteralExpression> arrays =
                 PsiTreeUtil.findChildrenOfType(psiFile, JSArrayLiteralExpression.class);
         for (JSArrayLiteralExpression arr : arrays) {
             parseArr(arr);
diff --git a/src/test/java/io/github/linwancen/plugin/show/lang/base/DocSkipTest.java b/src/test/java/io/github/linwancen/plugin/show/lang/base/DocSkipTest.java
index fa933ae..1fc920d 100644
--- a/src/test/java/io/github/linwancen/plugin/show/lang/base/DocSkipTest.java
+++ b/src/test/java/io/github/linwancen/plugin/show/lang/base/DocSkipTest.java
@@ -2,6 +2,7 @@ package io.github.linwancen.plugin.show.lang.base;
 
 
 import groovy.json.JsonOutput;
+import org.jetbrains.annotations.NotNull;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
@@ -33,7 +34,7 @@ class DocSkipTest {
     @Test
     void skipName() {
         // o include, x skip
-        boolean[][][] results = {{
+        @NotNull boolean[][][] results = {{
                 // "java" -- name
                 // {}, {"java"}, {"io.b"}, {"java", "io.b"} -- exclude
                 {o, x, o, x}, // {},
@@ -56,18 +57,18 @@ class DocSkipTest {
                 {o, o, x, x}, // {"java", "io"},
         }};
         for (int i = 0, namesLength = names.length; i < namesLength; i++) {
-            String name = names[i];
+            @NotNull String name = names[i];
             loopTest(name, results[i]);
         }
     }
 
-    private void loopTest(String name, boolean[][] results) {
+    private void loopTest(@NotNull String name, boolean[][] results) {
         for (int includeIndex = 0, includesLength = includes.length; includeIndex < includesLength; includeIndex++) {
-            Pattern include = includes[includeIndex];
+            @NotNull Pattern include = includes[includeIndex];
             for (int excludeIndex = 0, excludesLength = excludes.length; excludeIndex < excludesLength; excludeIndex++) {
-                Pattern exclude = excludes[excludeIndex];
+                @NotNull Pattern exclude = excludes[excludeIndex];
                 boolean isSkip = DocSkip.skipText(name, include, exclude);
-                String tip =
+                @NotNull String tip =
                         name + "==" + JsonOutput.toJson(include) + "!=" + JsonOutput.toJson(exclude) + "=>" + isSkip;
                 System.out.println(tip);
                 // o true include, x false skip, so use '!'
@@ -79,7 +80,7 @@ class DocSkipTest {
 
     @Test
     void include() {
-        boolean[][] results = {
+        @NotNull boolean[][] results = {
                 // {"java", "io.a", "io.b"} -- name
                 {o, o, o}, // {},
                 {o, x, x}, // {"java"},
@@ -91,7 +92,7 @@ class DocSkipTest {
 
     @Test
     void exclude() {
-        boolean[][] results = {
+        @NotNull boolean[][] results = {
                 // {"java", "io.a", "io.b"} ... names
                 {x, x, x}, // {},
                 {o, x, x}, // {"java"},
@@ -101,13 +102,13 @@ class DocSkipTest {
         loopTest(DocSkip::exclude, results);
     }
 
-    private void loopTest(BiPredicate<String, Pattern> biPredicate, boolean[][] results) {
+    private void loopTest(@NotNull BiPredicate<String, Pattern> biPredicate, boolean[][] results) {
         for (int includeIndex = 0, includesLength = includes.length; includeIndex < includesLength; includeIndex++) {
-            Pattern include = includes[includeIndex];
+            @NotNull Pattern include = includes[includeIndex];
             for (int nameIndex = 0, namesLength = names.length; nameIndex < namesLength; nameIndex++) {
-                String name = names[nameIndex];
+                @NotNull String name = names[nameIndex];
                 boolean result = biPredicate.test(name, include);
-                String tip = name + "==" + JsonOutput.toJson(include) + "=>" + result;
+                @NotNull String tip = name + "==" + JsonOutput.toJson(include) + "=>" + result;
                 System.out.println(tip);
                 Assertions.assertEquals(results[includeIndex][nameIndex], result, tip);
             }