Added several useful classes

classpath/java/lang/Enum.java

@@ -0,0 +1,38 @@
+package java.lang;
+
+import java.lang.reflect.Method;
+
+public abstract class Enum<E extends Enum<E>> {
+  private final String name;
+  private final int ordinal;
+
+  public Enum(String name, int ordinal) {
+    this.name = name;
+    this.ordinal = ordinal;
+  }
+
+  public int compareTo(E other) {
+    return ordinal - other.ordinal;
+  }
+
+  public static <T extends Enum<T>> T valueOf(Class<T> enumType, String name) {
+    if (name != null) {
+      try {
+        Method method = enumType.getMethod("values");
+        Enum values[] = (Enum[])(method.invoke(null));
+        for (Enum value : values) {
+          if (name.equals(value.name)) {
+            return (T) value;
+          }
+        }
+      } catch (Exception ex) {
+        throw new RuntimeException(ex);
+      }
+    }
+    return null;
+  }
+
+  public int ordinal() {
+    return ordinal;
+  }
+}

classpath/java/lang/IncompatibleClassChangeError.java

@@ -0,0 +1,11 @@
+package java.lang;
+
+public class IncompatibleClassChangeError extends LinkageError {
+  public IncompatibleClassChangeError(String message) {
+    super(message);
+  }
+
+  public IncompatibleClassChangeError() {
+    super();
+  }
+}

classpath/java/lang/NoSuchFieldError.java

@@ -0,0 +1,11 @@
+package java.lang;
+
+public class NoSuchFieldError extends IncompatibleClassChangeError {
+  public NoSuchFieldError(String message) {
+    super(message);
+  }
+
+  public NoSuchFieldError() {
+    super();
+  }
+}

classpath/java/lang/annotation/Annotation.java

@@ -0,0 +1,4 @@
+package java.lang.annotation;
+
+public interface Annotation {
+}