[CQ] Cleanup in the singleton utils package

flutter-idea/src/io/flutter/jxbrowser/JxBrowserManager.java

@@ -87,19 +87,17 @@ else if (Objects.equals(info.getMajorVersion(), "2020")) {
   public static final String ANALYTICS_CATEGORY = "jxbrowser";
   private static InstallationFailedReason latestFailureReason;
   private final JxBrowserUtils jxBrowserUtils;
-  private final FileUtils fileUtils;
 
   @VisibleForTesting
-  protected JxBrowserManager(@NotNull JxBrowserUtils jxBrowserUtils, @NotNull FileUtils fileUtils) {
+  protected JxBrowserManager(@NotNull JxBrowserUtils jxBrowserUtils) {
     this.jxBrowserUtils = jxBrowserUtils;
-    this.fileUtils = fileUtils;
   }
 
   @NotNull
   public static JxBrowserManager getInstance() {
     if (manager == null) {
       //noinspection ConstantConditions
-      manager = new JxBrowserManager(new JxBrowserUtils(), FileUtils.getInstance());
+      manager = new JxBrowserManager(new JxBrowserUtils());
     }
     return manager;
   }
@@ -229,7 +227,7 @@ public void setUp(@NotNull String projectName) {
 
     LOG.info(projectName + ": Installing JxBrowser");
 
-    final boolean directoryExists = fileUtils.makeDirectory(DOWNLOAD_PATH);
+    final boolean directoryExists = FileUtils.makeDirectory(DOWNLOAD_PATH);
     if (!directoryExists) {
       LOG.info(projectName + ": Unable to create directory for JxBrowser files");
       setStatusFailed(new InstallationFailedReason(FailureType.DIRECTORY_CREATION_FAILED));
@@ -251,7 +249,7 @@ public void setUp(@NotNull String projectName) {
     boolean allDownloaded = true;
     for (String fileName : fileNames) {
       assert fileName != null;
-      if (!fileUtils.fileExists(getFilePath(fileName))) {
+      if (!FileUtils.fileExists(getFilePath(fileName))) {
         allDownloaded = false;
         break;
       }
@@ -268,7 +266,7 @@ public void setUp(@NotNull String projectName) {
     for (String fileName : fileNames) {
       assert fileName != null;
       final String filePath = getFilePath(fileName);
-      if (!fileUtils.deleteFile(filePath)) {
+      if (!FileUtils.deleteFile(filePath)) {
         LOG.info(projectName + ": Existing file could not be deleted - " + filePath);
       }
     }
@@ -350,7 +348,7 @@ private void loadClasses(@NotNull String[] fileNames) {
           paths.add(Paths.get(getFilePath(fileName)));
         }
         //noinspection ConstantConditions
-        fileUtils.loadPaths(this.getClass().getClassLoader(), paths);
+        FileUtils.loadPaths(this.getClass().getClassLoader(), paths);
       }
       catch (Exception ex) {
         LOG.info("Failed to load JxBrowser file", ex);

flutter-idea/src/io/flutter/utils/AsyncUtils.java

@@ -15,13 +15,21 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;
 
+import org.jetbrains.annotations.NotNull;
+
 public class AsyncUtils {
+
+  private AsyncUtils() {
+    throw new AssertionError("No instances.");
+  }
+
   /**
    * Helper to get the value of a future on the UI thread.
    * <p>
    * The action will never be called if the future is cancelled.
    */
-  public static <T> void whenCompleteUiThread(CompletableFuture<T> future, BiConsumer<? super T, ? super Throwable> action) {
+  public static <T> void whenCompleteUiThread(@NotNull CompletableFuture<T> future,
+                                              @NotNull BiConsumer<? super T, ? super Throwable> action) {
     future.whenCompleteAsync(
       (T value, Throwable throwable) -> {
         // Exceptions due to the Future being cancelled need to be treated
@@ -39,7 +47,7 @@ public static <T> void whenCompleteUiThread(CompletableFuture<T> future, BiConsu
     );
   }
 
-  public static void invokeLater(Runnable runnable) {
+  public static void invokeLater(@NotNull Runnable runnable) {
     final Application app = ApplicationManager.getApplication();
     if (app == null || app.isUnitTestMode()) {
       // This case existing to support unit testing.
@@ -50,7 +58,7 @@ public static void invokeLater(Runnable runnable) {
     }
   }
 
-  public static void invokeAndWait(Runnable runnable) throws ProcessCanceledException {
+  public static void invokeAndWait(@NotNull Runnable runnable) throws ProcessCanceledException {
     final Application app = ApplicationManager.getApplication();
     if (app == null || app.isUnitTestMode()) {
       try {

flutter-idea/src/io/flutter/utils/CollectionUtils.java

@@ -14,7 +14,9 @@
 import java.util.stream.Stream;
 
 public class CollectionUtils {
+
   private CollectionUtils() {
+    throw new AssertionError("No instances.");
   }
 
   public static <T> boolean anyMatch(@NotNull T[] in, @NotNull final Predicate<T> predicate) {

flutter-idea/src/io/flutter/utils/ElementIO.java

@@ -16,6 +16,11 @@
  * Utilities for reading and writing IntelliJ run configurations to and from the disk.
  */
 public class ElementIO {
+
+  private ElementIO() {
+    throw new AssertionError("No instances.");
+  }
+
   public static void addOption(@NotNull Element element, @NotNull String name, @Nullable String value) {
     if (value == null) return;
 
@@ -25,7 +30,7 @@ public static void addOption(@NotNull Element element, @NotNull String name, @Nu
     element.addContent(child);
   }
 
-  public static Map<String, String> readOptions(Element element) {
+  public static Map<String, String> readOptions(@NotNull Element element) {
     final Map<String, String> result = new HashMap<>();
     for (Element child : element.getChildren()) {
       if ("option".equals(child.getName())) {

flutter-idea/src/io/flutter/utils/FileUtils.java

@@ -5,68 +5,63 @@
  */
 package io.flutter.utils;
 
-import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.util.lang.UrlClassLoader;
-import com.jetbrains.lang.dart.DartFileType;
-import org.jetbrains.annotations.NotNull;
 
 import java.io.File;
 import java.nio.file.Path;
 import java.util.List;
 
-public class FileUtils {
-  private static FileUtils fileUtils;
+import org.jetbrains.annotations.NotNull;
 
-  public static FileUtils getInstance() {
-    if (fileUtils == null) {
-      fileUtils = new FileUtils();
-    }
-    return fileUtils;
+public class FileUtils {
+
+  private FileUtils() {
+    throw new AssertionError("No instances.");
   }
 
   /**
    * Makes a directory at the provided path.
+   *
    * @param path path of the directory to be created.
    * @return true if the directory already existed, or if it was successfully created; false if the directory could not be created.
    */
-  public boolean makeDirectory(String path) {
+  public static boolean makeDirectory(@NotNull String path) {
     final File directory = new File(path);
     if (!directory.exists()) {
       return directory.mkdirs();
     }
     return true;
   }
 
-  public boolean fileExists(String path) {
+  public static boolean fileExists(@NotNull String path) {
     final File file = new File(path);
     return file.exists();
   }
 
   /**
    * Deletes a file at the provided path.
+   *
    * @param path path of the file to be deleted.
    * @return true if the file does not exist, or if it was successfully deleted; false if the file could not be deleted.
    */
-  public boolean deleteFile(String path) {
+  public static boolean deleteFile(@NotNull String path) {
     final File file = new File(path);
     if (file.exists()) {
       return file.delete();
     }
     return true;
   }
+
   /**
    * Loads a list of file paths with a class loader.
-   *
+   * <p>
    * This is only available for versions 211.4961.30 and later.
-   * @param classLoader classloader that can be used as a UrlClassLoader to load the files.
-   * @param paths list of file paths to load.
+   *
+   * @param classLoader classloader that can be used as an UrlClassLoader to load the files.
+   * @param paths       list of file paths to load.
    */
-  public void loadPaths(ClassLoader classLoader, List<Path> paths) {
-    final UrlClassLoader urlClassLoader = (UrlClassLoader) classLoader;
+  public static void loadPaths(@NotNull ClassLoader classLoader, @NotNull List<Path> paths) {
+    final UrlClassLoader urlClassLoader = (UrlClassLoader)classLoader;
     urlClassLoader.addFiles(paths);
   }
-
-  public static boolean isDartFile(@NotNull VirtualFile file) {
-    return file.getFileType().equals(DartFileType.INSTANCE);
-  }
 }

flutter-idea/src/io/flutter/utils/FlutterModuleUtils.java

@@ -49,6 +49,7 @@ public class FlutterModuleUtils {
   public static final String DEPRECATED_FLUTTER_MODULE_TYPE_ID = "WEB_MODULE";
 
   private FlutterModuleUtils() {
+    throw new AssertionError("No instances.");
   }
 
   /**

flutter-idea/src/io/flutter/utils/JsonUtils.java

@@ -6,6 +6,7 @@
 package io.flutter.utils;
 
 import com.google.gson.*;
+
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
@@ -18,6 +19,7 @@
 public class JsonUtils {
 
   private JsonUtils() {
+    throw new AssertionError("No instances.");
   }
 
   @Nullable

flutter-idea/src/io/flutter/utils/OpenApiUtils.java

@@ -23,6 +23,10 @@
 
 public class OpenApiUtils {
 
+  private OpenApiUtils() {
+    throw new AssertionError("No instances.");
+  }
+
   public static @NotNull VirtualFile @NotNull [] getContentRoots(@NotNull Module module) {
     var moduleRootManager = ModuleRootManager.getInstance(module);
     return moduleRootManager == null ? VirtualFile.EMPTY_ARRAY : moduleRootManager.getContentRoots();

flutter-idea/src/io/flutter/utils/SystemUtils.java

@@ -12,21 +12,26 @@
 import com.intellij.execution.util.ExecUtil;
 import com.intellij.openapi.util.SystemInfo;
 import com.intellij.util.concurrency.AppExecutorUtil;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
 import java.util.concurrent.CompletableFuture;
 
 public class SystemUtils {
 
+  private SystemUtils() {
+    throw new AssertionError("No instances.");
+  }
+
   /**
    * Locate a given command-line tool given its name.
    * <p>
    * This is used to locate binaries that are not pre-installed. If it is necessary to find pre-installed
    * binaries it will require more work, especially on Windows.
    */
   @Nullable
-  public static String which(String toolName) {
+  public static String which(@NotNull String toolName) {
     final File gitExecutableFromPath =
       PathEnvironmentVariableUtil.findInPath(SystemInfo.isWindows ? toolName + ".exe" : toolName, getPath(), null);
     if (gitExecutableFromPath != null) {
@@ -45,7 +50,7 @@ private static String getPath() {
    * <p>
    * This is a non-blocking equivalient to {@link ExecUtil#execAndGetOutput(GeneralCommandLine)}.
    */
-  public static CompletableFuture<ProcessOutput> execAndGetOutput(GeneralCommandLine cmd) {
+  public static CompletableFuture<ProcessOutput> execAndGetOutput(@NotNull GeneralCommandLine cmd) {
     final CompletableFuture<ProcessOutput> future = new CompletableFuture<>();
 
     AppExecutorUtil.getAppExecutorService().submit(() -> {

flutter-idea/src/io/flutter/utils/UIUtils.java

@@ -10,6 +10,11 @@
 import org.jetbrains.annotations.NotNull;
 
 public class UIUtils {
+
+  private UIUtils() {
+    throw new AssertionError("No instances.");
+  }
+
   /**
    * All editor notifications in the Flutter plugin should get and set the background color from this method, which will ensure if any are
    * changed, they are all changed.

flutter-idea/src/io/flutter/utils/UrlUtils.java

@@ -4,19 +4,25 @@
 import java.net.URL;
 
 public class UrlUtils {
-    public static String generateHtmlFragmentWithHrefTags(String input) {
-        StringBuilder builder = new StringBuilder();
-        for (String token : input.split(" ")) {
-            if (!builder.isEmpty()) {
-                builder.append(" ");
-            }
-            try {
-                URL url = new URL(token);
-                builder.append("<a href=\"").append(url).append("\">").append(url).append("</a>");
-            } catch(MalformedURLException e) {
-                builder.append(token);
-            }
-        }
-        return builder.toString();
+
+  private UrlUtils() {
+    throw new AssertionError("No instances.");
+  }
+
+  public static String generateHtmlFragmentWithHrefTags(String input) {
+    StringBuilder builder = new StringBuilder();
+    for (String token : input.split(" ")) {
+      if (!builder.isEmpty()) {
+        builder.append(" ");
+      }
+      try {
+        URL url = new URL(token);
+        builder.append("<a href=\"").append(url).append("\">").append(url).append("</a>");
+      }
+      catch (MalformedURLException e) {
+        builder.append(token);
+      }
     }
+    return builder.toString();
+  }
 }

flutter-idea/testSrc/unit/io/flutter/jxbrowser/JxBrowserManagerTest.java

@@ -34,7 +34,7 @@ public void testSetUpIfKeyNotFound() throws FileNotFoundException {
     when(mockUtils.getJxBrowserKey()).thenThrow(new FileNotFoundException("Key not found"));
 
     // If the directory for JxBrowser files cannot be created, the installation should fail.
-    final JxBrowserManager manager = new JxBrowserManager(mockUtils, mock(FileUtils.class));
+    final JxBrowserManager manager = new JxBrowserManager(mockUtils);
 
     manager.setUp(projectName);
     Assert.assertEquals(JxBrowserStatus.INSTALLATION_FAILED, manager.getStatus());
@@ -49,7 +49,7 @@ public void testSetUpIfDirectoryFails() throws FileNotFoundException {
     when(mockFileUtils.makeDirectory(DOWNLOAD_PATH)).thenReturn(false);
 
     // If the directory for JxBrowser files cannot be created, the installation should fail.
-    final JxBrowserManager manager = new JxBrowserManager(mockUtils, mockFileUtils);
+    final JxBrowserManager manager = new JxBrowserManager(mockUtils);
 
     manager.setUp(projectName);
     Assert.assertEquals(JxBrowserStatus.INSTALLATION_FAILED, manager.getStatus());
@@ -65,7 +65,7 @@ public void testSetUpIfPlatformFileNotFound() throws FileNotFoundException {
     when(mockFileUtils.makeDirectory(DOWNLOAD_PATH)).thenReturn(true);
 
     // If the system platform is not found among JxBrowser files, then the installation should fail.
-    final JxBrowserManager manager = new JxBrowserManager(mockUtils, mockFileUtils);
+    final JxBrowserManager manager = new JxBrowserManager(mockUtils);
 
     manager.setUp(projectName);
     Assert.assertEquals(JxBrowserStatus.INSTALLATION_FAILED, manager.getStatus());
@@ -84,7 +84,7 @@ public void testSetUpIfAllFilesExist() throws FileNotFoundException {
     when(mockFileUtils.fileExists(anyString())).thenReturn(true);
 
     // If all of the files are already downloaded, we should load the existing files.
-    final JxBrowserManager manager = new JxBrowserManager(mockUtils, mockFileUtils);
+    final JxBrowserManager manager = new JxBrowserManager(mockUtils);
 
     manager.setUp(projectName);
     final String[] expectedFileNames = {PLATFORM_FILE_NAME, API_FILE_NAME, SWING_FILE_NAME};
@@ -108,7 +108,7 @@ public void testSetUpIfFilesMissing() throws FileNotFoundException {
     when(mockFileUtils.deleteFile(anyString())).thenReturn(true);
 
     // If any of our required files do not exist, we want to delete any existing files and start a download of all of the required files.
-    final JxBrowserManager manager = new JxBrowserManager(mockUtils, mockFileUtils);
+    final JxBrowserManager manager = new JxBrowserManager(mockUtils);
     final JxBrowserManager spy = spy(manager);
     final String[] expectedFileNames = {PLATFORM_FILE_NAME, API_FILE_NAME, SWING_FILE_NAME};
     doNothing().when(spy).downloadJxBrowser(expectedFileNames);