diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackManager.java b/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackManager.java
index cc4d38111..b247a2c01 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackManager.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackManager.java
@@ -20,8 +20,7 @@ package org.jackhuang.hmcl.game;
 import com.google.gson.JsonParseException;
 import org.jackhuang.hmcl.mod.Modpack;
 import org.jackhuang.hmcl.util.CompressingUtils;
-import org.jackhuang.hmcl.util.Constants;
-import org.jackhuang.hmcl.util.Lang;
+import org.jackhuang.hmcl.util.JsonUtils;
 import org.jackhuang.hmcl.util.StringUtils;
 
 import java.io.File;
@@ -82,9 +81,9 @@ public final class HMCLModpackManager {
      */
     public static Modpack readHMCLModpackManifest(File file) throws IOException, JsonParseException {
         String manifestJson = CompressingUtils.readTextZipEntry(file, "modpack.json");
-        Modpack manifest = Lang.requireJsonNonNull(Constants.GSON.fromJson(manifestJson, Modpack.class));
+        Modpack manifest = JsonUtils.fromNonNullJson(manifestJson, Modpack.class);
         String gameJson = CompressingUtils.readTextZipEntry(file, "minecraft/pack.json");
-        Version game = Lang.requireJsonNonNull(Constants.GSON.fromJson(gameJson, Version.class));
+        Version game = JsonUtils.fromNonNullJson(gameJson, Version.class);
         if (game.getJar() == null)
             if (StringUtils.isBlank(manifest.getVersion()))
                 throw new JsonParseException("Cannot recognize the game version of modpack " + file + ".");
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java b/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
index a79a1ebd1..f12f6a861 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
@@ -106,7 +106,7 @@ public final class ModpackHelper {
         else throw new IllegalStateException("Unrecognized modpack: " + modpack);
     }
 
-    public static Task getUpdateTask(Profile profile, File zipFile, String name, ModpackConfiguration configuration) throws UnsupportedModpackException, MismatchedModpackTypeException, IOException {
+    public static Task getUpdateTask(Profile profile, File zipFile, String name, ModpackConfiguration<?> configuration) throws UnsupportedModpackException, MismatchedModpackTypeException, IOException {
         Modpack modpack = ModpackHelper.readModpackManifest(zipFile);
 
         switch (configuration.getType()) {
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/setting/Accounts.java b/HMCL/src/main/java/org/jackhuang/hmcl/setting/Accounts.java
index dccc1d195..e12700207 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/setting/Accounts.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/setting/Accounts.java
@@ -73,9 +73,8 @@ public final class Accounts {
     }
 
     public static Optional<String> getCurrentCharacter(Map<Object, Object> storage) {
-        Optional<Map> properties = Lang.get(storage, "properties", Map.class);
-        if (!properties.isPresent()) return Optional.empty();
-        return Lang.get(properties.get(), "character", String.class);
+        return Lang.get(storage, "properties", Map.class)
+                .flatMap(properties -> Lang.get(properties, "character", String.class));
     }
 
     static String getAccountId(Account account) {
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/setting/Settings.java b/HMCL/src/main/java/org/jackhuang/hmcl/setting/Settings.java
index 047d97f7a..7146156ea 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/setting/Settings.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/setting/Settings.java
@@ -69,7 +69,7 @@ public class Settings {
     {
         for (Map<Object, Object> settings : SETTINGS.getAccounts()) {
             Optional<String> characterName = Accounts.getCurrentCharacter(settings);
-            AccountFactory factory = Accounts.ACCOUNT_FACTORY.get(Lang.get(settings, "type", String.class, ""));
+            AccountFactory<?> factory = Accounts.ACCOUNT_FACTORY.get(Lang.get(settings, "type", String.class, ""));
             if (factory == null || !characterName.isPresent()) {
                 // unrecognized account type, so remove it.
                 SETTINGS.getAccounts().remove(settings);
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/setting/VersionSetting.java b/HMCL/src/main/java/org/jackhuang/hmcl/setting/VersionSetting.java
index 6bc4a7c0c..b79465121 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/setting/VersionSetting.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/setting/VersionSetting.java
@@ -138,7 +138,7 @@ public final class VersionSetting {
         permSizeProperty.set(permSize);
     }
 
-    private final ImmediateIntegerProperty maxMemoryProperty = new ImmediateIntegerProperty(this, "maxMemory", (int) OperatingSystem.SUGGESTED_MEMORY);
+    private final ImmediateIntegerProperty maxMemoryProperty = new ImmediateIntegerProperty(this, "maxMemory", OperatingSystem.SUGGESTED_MEMORY);
 
     public ImmediateIntegerProperty maxMemoryProperty() {
         return maxMemoryProperty;
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/AccountsPage.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/AccountsPage.java
index 5d9c8ac1e..36b7b8ca8 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/AccountsPage.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/AccountsPage.java
@@ -214,19 +214,19 @@ public final class AccountsPage extends StackPane implements DecoratorPage {
         this.title.set(title);
     }
 
-    public static String accountException(Exception account) {
-        if (account instanceof InvalidCredentialsException) {
+    public static String accountException(Exception exception) {
+        if (exception instanceof InvalidCredentialsException) {
             return Main.i18n("account.failed.invalid_credentials");
-        } else if (account instanceof NoCharacterException) {
+        } else if (exception instanceof NoCharacterException) {
             return Main.i18n("account.failed.no_charactor");
-        } else if (account instanceof ServerDisconnectException) {
+        } else if (exception instanceof ServerDisconnectException) {
             return Main.i18n("account.failed.connect_authentication_server");
-        } else if (account instanceof InvalidTokenException) {
+        } else if (exception instanceof InvalidTokenException) {
             return Main.i18n("account.failed.invalid_token");
-        } else if (account instanceof InvalidPasswordException) {
+        } else if (exception instanceof InvalidPasswordException) {
             return Main.i18n("account.failed.invalid_password");
         } else {
-            return account.getClass() + ": " + ((Exception) account).getLocalizedMessage();
+            return exception.getClass() + ": " + exception.getLocalizedMessage();
         }
     }
 
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/FXUtils.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/FXUtils.java
index e7861c399..8eef22adc 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/FXUtils.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/FXUtils.java
@@ -94,19 +94,36 @@ public final class FXUtils {
         });
     }
 
-    public static <T> void addListener(Node node, String key, ObservableValue<T> value, Consumer<T> callback) {
-        ChangeListener<T> listener = (a, b, newValue) -> callback.accept(newValue);
-        node.getProperties().put(key, new Pair<>(callback, listener));
-        value.addListener(listener);
+    private static class ListenerPair<T> {
+        ObservableValue<T> value;
+        ChangeListener<? super T> listener;
+
+        ListenerPair(ObservableValue<T> value, ChangeListener<? super T> listener) {
+            this.value = value;
+            this.listener = listener;
+        }
+
+        void bind() {
+            value.addListener(listener);
+        }
+
+        void unbind() {
+            value.removeListener(listener);
+        }
     }
 
-    public static <T> void removeListener(Node node, String key) {
-        if (node.getProperties().get(key) instanceof Pair) {
-            Pair pair = (Pair) node.getProperties().get(key);
-            if (pair.getValue() instanceof ObservableValue && pair.getKey() instanceof ChangeListener) {
-                ((ObservableValue) pair.getValue()).removeListener((ChangeListener) pair.getKey());
-            }
-        }
+    public static <T> void addListener(Node node, String key, ObservableValue<T> value, Consumer<? super T> callback) {
+        ListenerPair<T> pair = new ListenerPair<>(value, (a, b, newValue) -> callback.accept(newValue));
+        node.getProperties().put(key, pair);
+        pair.bind();
+    }
+
+    public static void removeListener(Node node, String key) {
+        Lang.convert(node.getProperties().get(key), ListenerPair.class)
+                .ifPresent(info -> {
+                    info.unbind();
+                    node.getProperties().remove(key);
+                });
     }
 
     public static void setValidateWhileTextChanged(Node field, boolean validate) {
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/NoneMultipleSelectionModel.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/NoneMultipleSelectionModel.java
index 91418fbbc..cbebe3e2c 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/NoneMultipleSelectionModel.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/NoneMultipleSelectionModel.java
@@ -21,13 +21,9 @@ import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 import javafx.scene.control.MultipleSelectionModel;
 
-public final class NoneMultipleSelectionModel<T> extends MultipleSelectionModel<T> {
-    private static final NoneMultipleSelectionModel INSTANCE = new NoneMultipleSelectionModel();
-    private NoneMultipleSelectionModel() {}
+public class NoneMultipleSelectionModel<T> extends MultipleSelectionModel<T> {
 
-    @SuppressWarnings("unchecked")
-    public static <T> NoneMultipleSelectionModel<T> getInstance() {
-        return (NoneMultipleSelectionModel<T>) INSTANCE;
+    public NoneMultipleSelectionModel() {
     }
 
     @Override
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/RipplerContainer.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/RipplerContainer.java
index 0f91804c9..df7073f5a 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/RipplerContainer.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/construct/RipplerContainer.java
@@ -217,10 +217,12 @@ public class RipplerContainer extends StackPane {
     private static class StyleableProperties {
 
         private static final CssMetaData<RipplerContainer, Paint> RIPPLER_FILL = new CssMetaData<RipplerContainer, Paint>("-jfx-rippler-fill", StyleConverter.getPaintConverter(), Color.rgb(0, 200, 255)) {
+            @Override
             public boolean isSettable(RipplerContainer control) {
                 return control.ripplerFill == null || !control.ripplerFill.isBound();
             }
 
+            @Override
             public StyleableProperty<Paint> getStyleableProperty(RipplerContainer control) {
                 return control.ripplerFillProperty();
             }
@@ -232,7 +234,7 @@ public class RipplerContainer extends StackPane {
         }
 
         static {
-            List<CssMetaData<? extends Styleable, ?>> styleables = new ArrayList<>(Parent.getClassCssMetaData());
+            List<CssMetaData<? extends Styleable, ?>> styleables = new ArrayList<>(Node.getClassCssMetaData());
             Collections.addAll(styleables, RIPPLER_FILL);
             STYLEABLES = Collections.unmodifiableList(styleables);
         }
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ExportWizardProvider.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ExportWizardProvider.java
index 5fdb9c969..8686237bf 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ExportWizardProvider.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ExportWizardProvider.java
@@ -44,7 +44,10 @@ public final class ExportWizardProvider implements WizardProvider {
 
     @Override
     public Object finish(Map<String, Object> settings) {
-        return new HMCLModpackExportTask(profile.getRepository(), version, (List<String>) settings.get(ModpackFileSelectionPage.MODPACK_FILE_SELECTION),
+        @SuppressWarnings("unchecked")
+        List<String> whitelist = (List<String>) settings.get(ModpackFileSelectionPage.MODPACK_FILE_SELECTION);
+
+        return new HMCLModpackExportTask(profile.getRepository(), version, whitelist,
                 new Modpack(
                         (String) settings.get(ModpackInfoPage.MODPACK_NAME),
                         (String) settings.get(ModpackInfoPage.MODPACK_AUTHOR),
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ModpackFileSelectionPage.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ModpackFileSelectionPage.java
index ee0dbfcad..1f8f1e025 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ModpackFileSelectionPage.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/export/ModpackFileSelectionPage.java
@@ -62,7 +62,7 @@ public final class ModpackFileSelectionPage extends StackPane implements WizardP
         FXUtils.loadFXML(this, "/assets/fxml/modpack/selection.fxml");
         rootNode = getTreeItem(profile.getRepository().getRunDirectory(version), "minecraft");
         treeView.setRoot(rootNode);
-        treeView.setSelectionModel(NoneMultipleSelectionModel.getInstance());
+        treeView.setSelectionModel(new NoneMultipleSelectionModel<>());
     }
 
     private CheckBoxTreeItem<String> getTreeItem(File file, String basePath) {
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/AppDataUpgrader.java b/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/AppDataUpgrader.java
index 8d36d8e25..a7e60e87f 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/AppDataUpgrader.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/AppDataUpgrader.java
@@ -56,7 +56,7 @@ public class AppDataUpgrader extends IUpgrader {
                 al.add("--noupdate");
                 AccessController.doPrivileged((PrivilegedExceptionAction<Void>) () -> {
                     new URLClassLoader(new URL[]{jar.toURI().toURL()},
-                            URLClassLoader.getSystemClassLoader().getParent()).loadClass(mainClass)
+                            ClassLoader.getSystemClassLoader().getParent()).loadClass(mainClass)
                             .getMethod("main", String[].class).invoke(null, new Object[]{al.toArray(new String[0])});
                     return null;
                 });
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/OfflineAccount.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/OfflineAccount.java
index 8090c9401..f3c65e610 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/OfflineAccount.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/OfflineAccount.java
@@ -47,6 +47,7 @@ public class OfflineAccount extends Account {
             throw new IllegalArgumentException("Username cannot be blank");
     }
 
+    @Override
     public UUID getUUID() {
         return UUIDTypeAdapter.fromString(uuid);
     }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/yggdrasil/AuthlibInjectorBuildInfo.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/yggdrasil/AuthlibInjectorBuildInfo.java
index f27b9650b..0d3ed21f8 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/yggdrasil/AuthlibInjectorBuildInfo.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/yggdrasil/AuthlibInjectorBuildInfo.java
@@ -1,9 +1,8 @@
 package org.jackhuang.hmcl.auth.yggdrasil;
 
 import com.google.gson.JsonParseException;
-import org.jackhuang.hmcl.util.Constants;
 import org.jackhuang.hmcl.util.Immutable;
-import org.jackhuang.hmcl.util.Lang;
+import org.jackhuang.hmcl.util.JsonUtils;
 import org.jackhuang.hmcl.util.NetworkUtils;
 
 import java.io.IOException;
@@ -36,7 +35,7 @@ public final class AuthlibInjectorBuildInfo {
     }
 
     public static AuthlibInjectorBuildInfo requestBuildInfo(String updateUrl) throws IOException, JsonParseException {
-        return Lang.requireJsonNonNull(Constants.GSON.fromJson(NetworkUtils.doGet(NetworkUtils.toURL(updateUrl)), AuthlibInjectorBuildInfo.class));
+        return JsonUtils.fromNonNullJson(NetworkUtils.doGet(NetworkUtils.toURL(updateUrl)), AuthlibInjectorBuildInfo.class);
     }
 
     public static final String UPDATE_URL = "https://authlib-injector.to2mbn.org/api/buildInfo";
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/launch/DefaultLauncher.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/launch/DefaultLauncher.java
index bdf3ae488..bfdcc85e8 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/launch/DefaultLauncher.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/launch/DefaultLauncher.java
@@ -198,7 +198,7 @@ public class DefaultLauncher extends Launcher {
     }
 
     private final Map<String, Supplier<Boolean>> forbiddens = Lang.mapOf(
-            new Pair<>("-Xincgc", () -> options.getJava().getParsedVersion() >= JavaVersion.JAVA_9)
+            new Pair<String, Supplier<Boolean>>("-Xincgc", () -> options.getJava().getParsedVersion() >= JavaVersion.JAVA_9)
     );
 
     protected Map<String, Supplier<Boolean>> getForbiddens() {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/CurseManifest.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/CurseManifest.java
index 90b9ecab6..1e013dbaf 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/CurseManifest.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/CurseManifest.java
@@ -20,15 +20,13 @@ package org.jackhuang.hmcl.mod;
 import com.google.gson.JsonParseException;
 import com.google.gson.annotations.SerializedName;
 import org.jackhuang.hmcl.util.CompressingUtils;
-import org.jackhuang.hmcl.util.Constants;
 import org.jackhuang.hmcl.util.Immutable;
-import org.jackhuang.hmcl.util.Lang;
+import org.jackhuang.hmcl.util.JsonUtils;
 
 import java.io.File;
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
-import java.util.Optional;
 
 /**
  *
@@ -120,7 +118,7 @@ public final class CurseManifest {
      */
     public static Modpack readCurseForgeModpackManifest(File f) throws IOException, JsonParseException {
         String json = CompressingUtils.readTextZipEntry(f, "manifest.json");
-        CurseManifest manifest = Lang.requireJsonNonNull(Constants.GSON.fromJson(json, CurseManifest.class));
+        CurseManifest manifest = JsonUtils.fromNonNullJson(json, CurseManifest.class);
         return new Modpack(manifest.getName(), manifest.getAuthor(), manifest.getVersion(), manifest.getMinecraft().getGameVersion(),
                 CompressingUtils.readTextZipEntryQuietly(f, "modlist.html").orElse( "No description"), manifest);
     }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Constants.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Constants.java
index 08ac96a2e..5526708e6 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Constants.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Constants.java
@@ -94,4 +94,8 @@ public final class Constants {
     public static <T> Predicate<T> falsePredicate() {
         return s -> false;
     }
+
+    public static <T> Consumer<T> emptyConsumer() {
+        return x -> {};
+    }
 }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateBooleanProperty.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateBooleanProperty.java
index af637d310..54ca83039 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateBooleanProperty.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateBooleanProperty.java
@@ -48,7 +48,7 @@ public class ImmediateBooleanProperty extends SimpleBooleanProperty {
         super.unbind();
     }
 
-    private Consumer<Boolean> listener = Lang.EMPTY_CONSUMER;
+    private Consumer<Boolean> listener = Constants.emptyConsumer();
     private final ChangeListener<Boolean> changeListener = (a, b, newValue) -> listener.accept(newValue);
 
     public void setChangedListener(Consumer<Boolean> listener) {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateDoubleProperty.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateDoubleProperty.java
index eb63b057d..f6937c132 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateDoubleProperty.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateDoubleProperty.java
@@ -49,7 +49,7 @@ public class ImmediateDoubleProperty extends SimpleDoubleProperty {
         super.unbind();
     }
 
-    private Consumer<Double> listener = Lang.EMPTY_CONSUMER;
+    private Consumer<Double> listener = Constants.emptyConsumer();
     private final ChangeListener<Number> changeListener = (a, b, newValue) -> listener.accept(newValue.doubleValue());
 
     public void setChangedListener(Consumer<Double> listener) {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateIntegerProperty.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateIntegerProperty.java
index 485c2f0be..49c4dea81 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateIntegerProperty.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateIntegerProperty.java
@@ -48,7 +48,7 @@ public class ImmediateIntegerProperty extends SimpleIntegerProperty {
         super.unbind();
     }
 
-    private Consumer<Integer> listener = Lang.EMPTY_CONSUMER;
+    private Consumer<Integer> listener = Constants.emptyConsumer();
     private final ChangeListener<Number> changeListener = (a, b, newValue) -> listener.accept(newValue.intValue());
 
     public void setChangedListener(Consumer<Integer> listener) {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateObjectProperty.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateObjectProperty.java
index 54361523e..d18f2c559 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateObjectProperty.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ImmediateObjectProperty.java
@@ -48,7 +48,7 @@ public class ImmediateObjectProperty<T> extends SimpleObjectProperty<T> {
         super.unbind();
     }
 
-    private Consumer<T> listener = Lang.EMPTY_CONSUMER;
+    private Consumer<T> listener = Constants.emptyConsumer();
     private final ChangeListener<T> changeListener = (a, b, newValue) -> listener.accept(newValue);
 
     public void setChangedListener(Consumer<T> listener) {
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/JsonUtils.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/JsonUtils.java
new file mode 100644
index 000000000..de5fe0a0b
--- /dev/null
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/JsonUtils.java
@@ -0,0 +1,15 @@
+package org.jackhuang.hmcl.util;
+
+import com.google.gson.JsonParseException;
+
+public final class JsonUtils {
+
+    private JsonUtils() {}
+
+    public static <T> T fromNonNullJson(String json, Class<T> classOfT) throws JsonParseException {
+        T parsed = Constants.GSON.fromJson(json, classOfT);
+        if (parsed == null)
+            throw new JsonParseException("Json object cannot be null.");
+        return parsed;
+    }
+}
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Lang.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Lang.java
index c41211ed9..3beebeeec 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Lang.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/Lang.java
@@ -5,8 +5,6 @@
  */
 package org.jackhuang.hmcl.util;
 
-import com.google.gson.JsonParseException;
-
 import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -22,19 +20,7 @@ public final class Lang {
     private Lang() {
     }
 
-    public static final Consumer EMPTY_CONSUMER = a -> {
-    };
-
-    public static <T> T requireJsonNonNull(T obj) throws JsonParseException {
-        return requireJsonNonNull(obj, "Json object cannot be null.");
-    }
-
-    public static <T> T requireJsonNonNull(T obj, String message) throws JsonParseException {
-        if (obj == null)
-            throw new JsonParseException(message);
-        return obj;
-    }
-
+    @SafeVarargs
     public static <K, V> Map<K, V> mapOf(Pair<K, V>... pairs) {
         HashMap<K, V> map = new HashMap<>();
         for (Pair<K, V> pair : pairs)
@@ -42,14 +28,14 @@ public final class Lang {
         return map;
     }
 
-    public static <K, V> V getOrPut(Map<K, V> map, K key, Supplier<V> defaultValue) {
+    public static <K, V> V computeIfAbsent(Map<K, V> map, K key, Supplier<V> computingFunction) {
         V value = map.get(key);
         if (value == null) {
-            V answer = defaultValue.get();
-            map.put(key, answer);
-            return answer;
-        } else
-            return value;
+            V newValue = computingFunction.get();
+            map.put(key, newValue);
+            return newValue;
+        }
+        return value;
     }
 
     public static <E extends Throwable> void throwable(Throwable exception) throws E {
@@ -230,8 +216,8 @@ public final class Lang {
         return convert(map.get(key), clazz, defaultValue);
     }
 
-    public static <T> List<T> merge(Collection<T> a, Collection<T> b) {
-        LinkedList<T> result = new LinkedList<>();
+    public static <T> List<T> merge(Collection<? extends T> a, Collection<? extends T> b) {
+        List<T> result = new ArrayList<>();
         if (a != null)
             result.addAll(a);
         if (b != null)
@@ -239,17 +225,6 @@ public final class Lang {
         return result;
     }
 
-    public static <T> List<T> merge(Collection<T> a, Collection<T> b, Collection<T> c) {
-        LinkedList<T> result = new LinkedList<>();
-        if (a != null)
-            result.addAll(a);
-        if (b != null)
-            result.addAll(b);
-        if (c != null)
-            result.addAll(c);
-        return result;
-    }
-
     public static void executeDelayed(Runnable runnable, TimeUnit timeUnit, long timeout, boolean isDaemon) {
         thread(() -> {
             try {
@@ -322,6 +297,7 @@ public final class Lang {
         }
     }
 
+    @SafeVarargs
     public static <T> T nonNull(T... t) {
         for (T a : t) if (a != null) return a;
         return null;
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/NetworkUtils.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/NetworkUtils.java
index 6bdc7f104..98806ad3e 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/NetworkUtils.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/NetworkUtils.java
@@ -17,10 +17,6 @@
  */
 package org.jackhuang.hmcl.util;
 
-import javax.net.ssl.HostnameVerifier;
-import javax.net.ssl.HttpsURLConnection;
-import javax.net.ssl.SSLContext;
-import javax.net.ssl.X509TrustManager;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -28,9 +24,6 @@ import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.Proxy;
 import java.net.URL;
-import java.security.GeneralSecurityException;
-import java.security.SecureRandom;
-import java.security.cert.X509Certificate;
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.Supplier;
@@ -46,41 +39,6 @@ public final class NetworkUtils {
     private NetworkUtils() {
     }
 
-    private static final X509TrustManager XTM = new X509TrustManager() {
-        @Override
-        public void checkClientTrusted(X509Certificate[] xcs, String string) {
-        }
-
-        @Override
-        public void checkServerTrusted(X509Certificate[] xcs, String string) {
-        }
-
-        @Override
-        public X509Certificate[] getAcceptedIssuers() {
-            return new X509Certificate[0];
-        }
-    };
-
-    private static final HostnameVerifier HNV = (a, b) -> true;
-
-    private static volatile boolean initHttps = false;
-
-    private static synchronized void initHttps() {
-        if (initHttps)
-            return;
-
-        initHttps = true;
-
-        System.setProperty("https.protocols", "SSLv3,TLSv1");
-        try {
-            SSLContext c = SSLContext.getInstance("SSL");
-            c.init(null, new X509TrustManager[] { XTM }, new SecureRandom());
-            HttpsURLConnection.setDefaultSSLSocketFactory(c.getSocketFactory());
-        } catch (GeneralSecurityException ignore) {
-        }
-        HttpsURLConnection.setDefaultHostnameVerifier(HNV);
-    }
-
     private static Supplier<String> userAgentSupplier = RandomUserAgent::randomUserAgent;
 
     public static String getUserAgent() {
@@ -92,7 +50,6 @@ public final class NetworkUtils {
     }
 
     public static HttpURLConnection createConnection(URL url, Proxy proxy) throws IOException {
-        initHttps();
         HttpURLConnection connection = (HttpURLConnection) url.openConnection(proxy);
         connection.setDoInput(true);
         connection.setUseCaches(false);
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/RandomUserAgent.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/RandomUserAgent.java
index 3795779e1..4aaf3731f 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/RandomUserAgent.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/RandomUserAgent.java
@@ -3,6 +3,9 @@ package org.jackhuang.hmcl.util;
 import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * Optifine has blocked Java's useragent, so we have to make up one.
+ */
 public class RandomUserAgent {
 
     private static final HashMap<String, String[]> uaMap = new HashMap<>();
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ReflectionHelper.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ReflectionHelper.java
index f2eb46ffe..3fb336020 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ReflectionHelper.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/ReflectionHelper.java
@@ -52,14 +52,14 @@ public final class ReflectionHelper {
         }
 
         PRIMITIVES = Lang.mapOf(
-                new Pair("byte", Byte.class),
-                new Pair("short", Short.class),
-                new Pair("int", Integer.class),
-                new Pair("long", Long.class),
-                new Pair("char", Character.class),
-                new Pair("float", Float.class),
-                new Pair("double", Double.class),
-                new Pair("boolean", Boolean.class)
+                new Pair<>("byte", Byte.class),
+                new Pair<>("short", Short.class),
+                new Pair<>("int", Integer.class),
+                new Pair<>("long", Long.class),
+                new Pair<>("char", Character.class),
+                new Pair<>("float", Float.class),
+                new Pair<>("double", Double.class),
+                new Pair<>("boolean", Boolean.class)
         );
     }
 
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/SimpleMultimap.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/SimpleMultimap.java
index 65e3cc6e9..9f83dc2c8 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/SimpleMultimap.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/SimpleMultimap.java
@@ -62,7 +62,7 @@ public final class SimpleMultimap<K, V> {
     }
 
     public Collection<V> get(K key) {
-        return Lang.getOrPut(map, key, valuer);
+        return Lang.computeIfAbsent(map, key, valuer);
     }
 
     public void put(K key, V value) {