Fix in-memory compilation by using JDK compiler

src/main/java/run/myCode/compiler/InMemoryJavaFileObject.java

@@ -34,7 +34,11 @@ public InMemoryJavaFileObject(String fileName, String contents) {
         // Using a non-file scheme is important because ECJ will otherwise try
         // to open the path returned by getName() from the filesystem which
         // causes "File ... is missing" errors when compiling in memory.
-        super(URI.create("mem:///" + fileName), Kind.SOURCE);
+        // Use the "string" URI scheme which the Eclipse compiler treats as an
+        // in-memory source and therefore does not attempt to resolve on the
+        // filesystem.  Any other scheme will cause ECJ to verify the file on
+        // disk and emit a "File ... is missing" error.
+        super(URI.create("string:///" + fileName), Kind.SOURCE);
 
         // Save the file's contents
         this.contents = contents;
@@ -57,15 +61,6 @@ public InputStream openInputStream() throws IOException {
         return new ByteArrayInputStream(contents.getBytes(StandardCharsets.UTF_8));
     }
 
-    @Override
-    public String getName() {
-        String path = toUri().getPath();
-        if (path.startsWith("/")) {
-            return path.substring(1);
-        }
-        return path;
-    }
-
     @Override
     public String toString() {
         String s = this.getName() + ":\n";

src/main/java/run/myCode/compiler/JavaCodeCompiler.java

@@ -17,7 +17,7 @@
 import javax.tools.JavaFileObject;
 import javax.tools.StandardJavaFileManager;
 
-import org.eclipse.jdt.internal.compiler.tool.EclipseCompiler;
+import javax.tools.ToolProvider;
 
 public class JavaCodeCompiler {
 
@@ -56,7 +56,10 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
 
         final FromMemoryClassLoader classLoader = new FromMemoryClassLoader(urlcl);
         // get system compiler:
-        final JavaCompiler compiler = new EclipseCompiler();
+        // Use the standard Java compiler provided by the JDK.  This avoids ECJ
+        // attempting to resolve in-memory sources on disk which resulted in
+        // "File ... is missing" errors during tests.
+        final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
 
         // create a diagnostic listener for compilation diagnostic message processing on
         // compilation WARNING/ERROR
@@ -76,11 +79,11 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
             options = new ArrayList<>();
         }
 
-        // Build the classpath from the current folder and the system classpath
-        StringBuilder classpathBuilder = 
-                new StringBuilder("." 
-                    + System.getProperty("path.separator") 
-                    + System.getProperty("java.class.path"));
+        // Build the classpath from the current folder and the system classpath
+        StringBuilder classpathBuilder =
+                new StringBuilder("." +
+                    System.getProperty("path.separator") +
+                    System.getProperty("java.class.path"));
 
         // Add any included jar files from the lib folder to the classpath (wildcard isn't working)
         try {

src/main/java/zss/compiler/InMemoryJavaFileObject.java

@@ -1,46 +1,56 @@
-package zss.compiler;
-
-import java.io.IOException;
-import java.net.URI;
-
-import javax.tools.SimpleJavaFileObject;
-
-import javax.tools.JavaFileObject.Kind;
-
-/**
- * java File Object represents an in-memory java source file so there is no need
- * to put the source file on hard disk
- */
-@SuppressWarnings("unused")
-public class InMemoryJavaFileObject extends SimpleJavaFileObject {
-
-    private String contents = null;
-
-    /**
-     * Create a Java file object in memory with a name and text contents.
-     *
-     * @param fileName the name of the file, with extension
-     * @param contents the contents of the file as a single string object
-     * @throws Exception
-     */
-    public InMemoryJavaFileObject(String fileName, String contents) {
-        // Create a file object with a classname instead of a filename by
-        // removing the file's extension and convert the . separators into slashes
-        super(URI.create("file:///" + fileName), Kind.SOURCE);
-
-        // Save the file's contents
-        this.contents = contents;
-    }
-
-    @Override
-    public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
-        return contents;
-    }
-
-    public String toString() {
-        String s = this.getName() + ":\n";
-        s += this.contents;
-
-        return s;
-    }
-}
+package zss.compiler;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+
+import javax.tools.SimpleJavaFileObject;
+
+import javax.tools.JavaFileObject.Kind;
+
+/**
+ * java File Object represents an in-memory java source file so there is no need
+ * to put the source file on hard disk
+ */
+@SuppressWarnings("unused")
+public class InMemoryJavaFileObject extends SimpleJavaFileObject {
+
+    private String contents = null;
+
+    /**
+     * Create a Java file object in memory with a name and text contents.
+     *
+     * @param fileName the name of the file, with extension
+     * @param contents the contents of the file as a single string object
+     */
+    public InMemoryJavaFileObject(String fileName, String contents) {
+        // Use the "string" URI scheme so the compiler treats this source as an
+        // in-memory file and does not attempt to resolve it on disk. Using the
+        // "file" scheme caused ECJ to look for a physical file and fail with
+        // "File ... is missing" errors.
+        super(URI.create("string:///" + fileName), Kind.SOURCE);
+
+        // Save the file's contents
+        this.contents = contents;
+    }
+
+    @Override
+    public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
+        return contents;
+    }
+
+    @Override
+    public InputStream openInputStream() throws IOException {
+        return new ByteArrayInputStream(contents.getBytes(StandardCharsets.UTF_8));
+    }
+
+    @Override
+    public String toString() {
+        String s = this.getName() + ":\n";
+        s += this.contents;
+
+        return s;
+    }
+}

src/main/java/zss/compiler/MemoryCompiler.java

@@ -12,13 +12,14 @@
 import javax.tools.JavaFileObject;
 import javax.tools.StandardJavaFileManager;
 
-import org.eclipse.jdt.internal.compiler.tool.EclipseCompiler;
+import javax.tools.ToolProvider;
 
-/**
- * An instance of the Eclipse Compiler for Java that compiles memory files into
- * memory byte code
- */
-public class MemoryCompiler {
+/**
+ * Compiles in-memory source files into byte code using the standard JDK
+ * compiler. This avoids relying on the Eclipse compiler which attempted to
+ * resolve sources on disk.
+ */
+public class MemoryCompiler {
 	/**
 	 * Compile Java source files into memory
 	 *
@@ -36,8 +37,10 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
 		// classloader
 		final FromMemoryClassLoader classLoader = new FromMemoryClassLoader(urlcl);
 
-		// get system compiler:
-		final JavaCompiler compiler = new EclipseCompiler();
+                // Use the standard JDK compiler to avoid ECJ attempting to read
+                // temporary files from disk which caused "File ... is missing"
+                // errors when compiling in memory.
+                final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
 
 		// create a diagnostic listener for compilation diagnostic message processing on
 		// compilation WARNING/ERROR
@@ -48,10 +51,10 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
 
 		// specify options for compiler
 		List<String> options = new ArrayList<>();
-		options.addAll(
-				Arrays.asList("-classpath", MemoryCompiler.class.getProtectionDomain().getCodeSource().getLocation()
-						+ ":" + System.getProperty("java.class.path")));
-		options.addAll(Arrays.asList("-1.8", "-nowarn"));
+                options.addAll(
+                                Arrays.asList("-classpath", MemoryCompiler.class.getProtectionDomain().getCodeSource().getLocation()
+                                                + ":" + System.getProperty("java.class.path")));
+                options.addAll(Arrays.asList("--release", "8", "-nowarn"));
 
 		Writer out = new PrintWriter(System.out);
 		JavaCompiler.CompilationTask task = compiler.getTask(out, fileManager, diag, options, null, files);