build file is allowed to be null in the model.

src/org/netbeans/gradle/project/model/GradleModelCache.java

@@ -42,19 +42,18 @@ public void removeChangeListener(ChangeListener listener) {
     public void addToCache(NbGradleModel model) {
         if (model == null) throw new NullPointerException("model");
 
-        File buildFile = FileUtil.toFile(model.getBuildFile());
+        File projectDir = FileUtil.toFile(model.getProjectDir());
 
         FileObject settingsFileObj = model.getSettingsFile();
         File settingsFile = settingsFileObj != null
                 ? FileUtil.toFile(settingsFileObj)
                 : null;
-        if (buildFile == null || (settingsFile == null && settingsFileObj != null)) {
-            // This can be null if the build file has been deleted as
-            // FileUtil.toFile returns null in this case.
+
+        if (projectDir == null || (settingsFile == null && settingsFileObj != null)) {
             return;
         }
 
-        CacheKey key = new CacheKey(buildFile, settingsFile);
+        CacheKey key = new CacheKey(projectDir, settingsFile);
 
         cacheLock.lock();
         try {
@@ -74,8 +73,8 @@ public void addToCache(NbGradleModel model) {
         }
     }
 
-    public NbGradleModel tryGet(File buildFile, File settingsFile) {
-        CacheKey key = new CacheKey(buildFile, settingsFile);
+    public NbGradleModel tryGet(File projectDir, File settingsFile) {
+        CacheKey key = new CacheKey(projectDir, settingsFile);
         cacheLock.lock();
         try {
             return cache.get(key);
@@ -85,19 +84,19 @@ public NbGradleModel tryGet(File buildFile, File settingsFile) {
     }
 
     private static class CacheKey {
-        private final File buildFile;
+        private final File projectDir;
         private final File settingsFile;
 
-        public CacheKey(File buildFile, File settingsFile) {
-            if (buildFile == null) throw new NullPointerException("buildFile");
-            this.buildFile = buildFile;
+        public CacheKey(File projectDir, File settingsFile) {
+            if (projectDir == null) throw new NullPointerException("buildFile");
+            this.projectDir = projectDir;
             this.settingsFile = settingsFile;
         }
 
         @Override
         public int hashCode() {
             int hash = 7;
-            hash = 89 * hash + this.buildFile.hashCode();
+            hash = 89 * hash + this.projectDir.hashCode();
             hash = 89 * hash + (this.settingsFile != null ? this.settingsFile.hashCode() : 0);
             return hash;
         }
@@ -114,7 +113,7 @@ public boolean equals(Object obj) {
                 return false;
             }
             final CacheKey other = (CacheKey)obj;
-            if (this.buildFile != other.buildFile && (!this.buildFile.equals(other.buildFile))) {
+            if (this.projectDir != other.projectDir && (!this.projectDir.equals(other.projectDir))) {
                 return false;
             }
             if (this.settingsFile != other.settingsFile && (this.settingsFile == null || !this.settingsFile.equals(other.settingsFile))) {

src/org/netbeans/gradle/project/model/GradleModelLoader.java

@@ -27,7 +27,6 @@
 import org.gradle.tooling.model.ExternalDependency;
 import org.gradle.tooling.model.GradleProject;
 import org.gradle.tooling.model.GradleTask;
-import org.gradle.tooling.model.HierarchicalElement;
 import org.gradle.tooling.model.Model;
 import org.gradle.tooling.model.idea.IdeaContentRoot;
 import org.gradle.tooling.model.idea.IdeaDependency;
@@ -60,22 +59,19 @@ public static void removeCacheChangeListener(ChangeListener listener) {
     }
 
     private static NbGradleModel tryGetFromCache(FileObject projectDir) {
-        try {
-            File buildFile = FileUtil.toFile(NbGradleModel.getBuildFile(projectDir));
-            FileObject settingFileObj = NbGradleModel.findSettingsGradle(projectDir);
-            File settingsFile = settingFileObj != null
-                    ? FileUtil.toFile(settingFileObj)
-                    : null;
-
-            return buildFile != null
-                    ? CACHE.tryGet(buildFile, settingsFile)
-                    : null;
-        } catch (IOException ex) {
-            LOGGER.log(Level.WARNING,
-                    "Failure to read project directory while attempting to"
-                    + " retrieve the model from the cache: " + projectDir, ex);
+        File projectDirFile = FileUtil.toFile(projectDir);
+        FileObject settingFileObj = NbGradleModel.findSettingsGradle(projectDir);
+        File settingsFile = settingFileObj != null
+                ? FileUtil.toFile(settingFileObj)
+                : null;
+        if (settingsFile == null && settingFileObj != null) {
+            LOGGER.log(Level.WARNING, "Settings file of the project disappeared: {0}", settingFileObj);
             return null;
         }
+
+        return projectDirFile != null
+                ? CACHE.tryGet(projectDirFile, settingsFile)
+                : null;
     }
 
     public static void tryGetModelFromCache(
@@ -385,13 +381,9 @@ private static NbGradleModel parseFromIdeaModel(
         for (NbGradleModule module: parsedModules.values()) {
             if (module != null && module != parsedMainModule) {
                 FileObject moduleDir = FileUtil.toFileObject(module.getModuleDir());
-                try {
-                    if (moduleDir != null) {
-                        NbGradleModel model = new NbGradleModel(moduleDir, settings, module);
-                        CACHE.addToCache(model);
-                    }
-                } catch (IOException ex) {
-                    LOGGER.log(Level.INFO, "Gradle project without build.gradle: {0}", module.getUniqueName());
+                if (moduleDir != null) {
+                    NbGradleModel model = new NbGradleModel(moduleDir, settings, module);
+                    CACHE.addToCache(model);
                 }
             }
         }

src/org/netbeans/gradle/project/model/NbGradleModel.java

@@ -1,6 +1,5 @@
 package org.netbeans.gradle.project.model;
 
-import java.io.IOException;
 import org.netbeans.gradle.project.GradleProjectConstants;
 import org.openide.filesystems.FileObject;
 
@@ -19,30 +18,34 @@ public final class NbGradleModel {
 
     public NbGradleModel(
             FileObject projectDir,
-            NbGradleModule mainModule) throws IOException {
+            NbGradleModule mainModule) {
         this(projectDir, findSettingsGradle(projectDir), mainModule);
     }
 
     public NbGradleModel(
             FileObject projectDir,
             FileObject settingsFile,
-            NbGradleModule mainModule) throws IOException {
+            NbGradleModule mainModule) {
+        this(projectDir, getBuildFile(projectDir), settingsFile, mainModule);
+    }
+
+    public NbGradleModel(
+            FileObject projectDir,
+            FileObject buildFile,
+            FileObject settingsFile,
+            NbGradleModule mainModule) {
         if (projectDir == null) throw new NullPointerException("projectDir");
         if (mainModule == null) throw new NullPointerException("mainModule");
 
         this.projectDir = projectDir;
         this.mainModule = mainModule;
 
-        this.buildFile = getBuildFile(projectDir);
+        this.buildFile = buildFile;
         this.settingsFile = settingsFile;
     }
 
-    public static FileObject getBuildFile(FileObject projectDir) throws IOException {
-        FileObject buildFile = projectDir.getFileObject(GradleProjectConstants.BUILD_FILE_NAME);
-        if (buildFile == null) {
-            throw new IOException("Missing build.gradle in the project directory: " + projectDir);
-        }
-        return buildFile;
+    public static FileObject getBuildFile(FileObject projectDir) {
+        return projectDir.getFileObject(GradleProjectConstants.BUILD_FILE_NAME);
     }
 
     public static FileObject findSettingsGradle(FileObject projectDir) {

src/org/netbeans/gradle/project/view/GradleProjectChildFactory.java

@@ -131,7 +131,9 @@ public Image getOpenedIcon(int type) {
     private void addProjectFiles(List<SingleNodeFactory> toPopulate) throws DataObjectNotFoundException {
         NbGradleModel model = project.getCurrentModel();
         FileObject buildGradle = model.getBuildFile();
-        addGradleFile(buildGradle, toPopulate);
+        if (buildGradle != null) {
+            addGradleFile(buildGradle, toPopulate);
+        }
 
         FileObject settingsGradle = model.getSettingsFile();
         if (settingsGradle != null) {