| Name | Description | Type | Package | Framework |
| Abort | Throwing an instance of this class causes (silent) termination of the main compiler method. | Class | com.sun.tools.javac.util | Fiji |
| BaseFileManager | Utility methods for building a filemanager. | Class | com.sun.tools.javac.util | Fiji |
| Bits | A class for extensible, mutable bit sets. | Class | com.sun.tools.javac.util | Fiji |
| ByteBuffer | A byte buffer is a flexible array which grows when elements are appended. | Class | com.sun.tools.javac.util | Fiji |
| Convert | Utility class for static conversion methods between numbers and strings in various formats. | Class | com.sun.tools.javac.util | Fiji |
| DiagnosticFormatter | A formatter for diagnostic messages. | Class | com.sun.tools.javac.util | Fiji |
| FatalError | Throwing an instance of this class causes immediate termination of the main compiler method. | Class | com.sun.tools.javac.util | Fiji |
| JCDiagnostic | An abstraction of a diagnostic message generated by the compiler. | Class | com.sun.tools.javac.util | Fiji |
| JCDiagnostic .DiagnosticPosition | A DiagnosticPosition provides information about the positions in a file that gave rise to a diagnostic. | Interface | com.sun.tools.javac.util.JCDiagnostic | Fiji |
| JCDiagnostic .DiagnosticSource | A simple abstraction of a source file, as needed for use in a diagnostic message. | Interface | com.sun.tools.javac.util.JCDiagnostic | Fiji |
| JCDiagnostic .DiagnosticType | A DiagnosticType defines the type of the diagnostic. | Class | com.sun.tools.javac.util.JCDiagnostic | Fiji |
| JCDiagnostic .Factory | A factory for creating diagnostic objects. | Class | com.sun.tools.javac.util.JCDiagnostic | Fiji |
| JCDiagnostic .SimpleDiagnosticPosition | A DiagnosticPosition that simply identifies a position, but no related tree node, as the location for a diagnostic. | Class | com.sun.tools.javac.util.JCDiagnostic | Fiji |
| LayoutCharacters | An interface containing layout character constants used in Java This is NOT part of any supported API. | Interface | com.sun.tools.javac.util | Fiji |
| List | A class for generic linked lists. | Class | com.sun.tools.javac.util | Fiji |
| ListBuffer | A class for constructing lists by appending elements. | Class | com.sun.tools.javac.util | Fiji |
| Log | A class for error logs. | Class | com.sun.tools.javac.util | Fiji |
| MandatoryWarningHandler | A handler to process mandatory warnings, setting up a deferred diagnostic to be printed at the end of the compilation if some warnings get suppressed | Class | com.sun.tools.javac.util | Fiji |
| Messages | Support for localized messages. | Class | com.sun.tools.javac.util | Fiji |
| Name | An abstraction for internal compiler strings. | Class | com.sun.tools.javac.util | Fiji |
| Name .Table | Class | com.sun.tools.javac.util.Name | Fiji | |
| Options | A table of all command-line options. | Class | com.sun.tools.javac.util | Fiji |
| Pair | A generic class for pairs. | Class | com.sun.tools.javac.util | Fiji |
| Position | A class that defines source code positions as simple character offsets from the beginning of the file. | Class | com.sun.tools.javac.util | Fiji |
| Position .LineMap | Interface | com.sun.tools.javac.util.Position | Fiji | |
| Position .LineTabMapImpl | A LineMap that handles tab expansion correctly. | Class | com.sun.tools.javac.util.Position | Fiji |
| PropagatedException | Used to propagate exceptions through to the user. | Class | com.sun.tools.javac.util | Fiji |
| Warner | An interface to support optional warnings, needed for support of unchecked conversions and unchecked casts. | Class | com.sun.tools.javac.util | Fiji |