Programming for the Java™ Virtual Machine

Joshua Engel is a programmer, computer scientist, and acknowledged expert in the Java virtual machine. He is Chief Software Developer for Knowledge Bus, Inc. (www.knowledgebus.com) During his extensive programming career, he has worked with dozens of programming languages and even designed a few of his own. 0201309726AB04062001

Preface.


1. Introduction to the Java Virtual Machine.


Java Virtual Machine and Java.



What Is the Java Virtual Machine?



Instruction Set.



class File Format.



Verification.



Java Platform.



Organization of the Java Virtual Machine.



Class Area.



Java Stack.



Heap.



Native Method Stacks.



Example.



Garbage Collection.



Finalization.



Timing of Garbage Collection.



JVM Implementations.



Versions of the Virtual Machine.



Future of the Java Virtual Machine.



2. Oolong.


Hello, World.



.class and .super Directives.



main Method.



Instructions.



Structure of an Oolong Program.



Defining the Class.



Superclasses.



Declaring Fields.



Declaring Methods.



Interfaces.



3. Writing Methods.


Some Definitions.



Types.



Numeric Types.



Object Types.



Type returnAddress.



Mnemonic Naming Conventions.



Testing Code Examples.



Returns.



Constants.



General Constants.



Small Constants and null.



Local Variables.



Initializing Variables.



Local Variables as Method Arguments.



Math.



Arithmetic Operations.



Nonnumbers and Infinity.



Bitwise Operations.



Floating-Point Arithmetic and strictfp.



Type Conversions.



Conversion Example.



Widening and Narrowing.



Stack Manipulations.



Arrays of Numbers.



Just Biding Your Time.



4. Classes and Objects.


What Is an Object?



Objects and References.



Class Names.



Packages.



Creating Objects.


Constructors.


Using Fields.


Types and getfield.



Inheriting Fields.



Changing Field Values.



Invoking Methods on Objects.



Virtual Invocation.



Method Inheritance and Overriding.



Overloading and Method Matching.



Invoking a Method Directly.



invokespecial and super.



Casting.



Casting, Fields, Methods, and Java.



Returning Objects.



Interfaces.



Static Fields and Methods.



Class Initialization.



Arrays.



Arrays of Reference.



Multidimensional Arrays.



Length of Arrays.



5. Control Instructions.


Comparing Integers.



Comparing References.



Other Comparisons.



Switches.



Subroutines.



Exceptions.



Multiple Exception Handlers.



.throws Directive.



Other Ways to Throw Exceptions.



A Gentler Way of Checking Type.



6. Verification Process.


How the Verification Algorithm Works.



Is It a Structurally Valid class File?



Are All Constant References Correct?



Will Each Instruction Always Find a Correctly Formed Stack and Local Variable Array?



Example 1: Hello, World.



Example 2: gotos and ifs.



Example 3: Code That Doesn’t Verify.



Example 4: Dealing with Subclasses.



Algorithm.



Do External References Check Out?



Java Language and Verification Algorithm.



Fooling the Virtual Machine with a Java Compiler.



Other Languages and the Verification Algorithm.



Other Safety Requirements.



Checking Verification.



7. Debugging.


Debugging Directives in Oolong.



.source Directive and .line Directives.



.var Directive.



Debugging Oolong Programs.



Runtime Tracing.



8. Class Loaders.


How Classes Are Loaded.



Loading.



Linking.



Loading Classes without a Class Loader.



Making Your Own Class Loader.



Caching Classes.



Examples.



Working with Class Objects.



Reflection.



9. Inside a Java class File.


class File Header.



Constant Pool.



UTF8 Entries.



Constant Entries.



Field, Method, and Class Entries.



Class Information.



Fields and Methods.



Class Attributes.



Other Attributes.



ConstantValue Attribute.



Exceptions Attribute.



InnerClasses Attribute.



10. Compiling Java.


Expressions and Statements.



Expression Types.



Numeric Types.



Object Types.



Expression Result Types.



Compile-Time Types and Type Restrictions.



Type Safety and Verifiability.



Compiling Statements and Expressions.



Local Variable Declarations.



Fields and Variables.



Abbreviations.



Other Assignments.



Assignments as Expressions.



Type-Checking in Assignments.



Creating New Objects.



Class Name Abbreviations.



Arithmetic Expressions.



Numeric Coercions.



Casting Numeric Values.



Operator.



Method Calls.



Virtual Method Calls.



Static Method Calls.



Example of Method Calls.



Overriding.



Overloading.



Interfaces.



Expressions as Statements.



Ifs and Booleans.



Boolean Values.



if Statements.



Comparisons.



Floating-Point Comparisons and NaN.



Integer Comparisons.



References and Object Equality.



Boolean Operators.



Other Control Structures.



Loops.



Compiling Control Constructs.



Compound Statements and Verification.



Returns.



Field Declarations.



Method Declarations.



Constructors.



Using Other Constructors in the Same Class.



Default Constructors.



Field Initializers and the Constructor.



Conclusion.



11. Compiling Other Languages.


Java Version 1.1.



Class Literals.



Inner Classes.



Variable Scoping with Inner Classes.



Regular Expressions.



Iterators.



Iterators in Sather.



Implementing Iterators.



Iterators with Arguments.



Using Iterators.



Parameterized Types.



Implementing Parameterized Types with a Generic Class.



Implementing Parameterized Types as Templates.



Multiple Inheritance.



Interfaces for Multiple Inheritance.



Implementing the Interfaces.



Fields.



Conclusion.



12. Implementing Scheme.


Scheme Concepts.



Compiling Scheme into Bytecodes.



Compiling Lambda Expressions.



Example.



Scheme Library.



Optimizing Scheme.



Static Scoping.



Using Local Variables.



Inlining.



Tail Recursion.



Using Type Information.



13. Implementing Prolog.


Introduction to Prolog.



Asking Questions.



Binding Patterns.



Implications.



Binding Patterns and Implications.



Facts as Rules.



More About Unification.



Implementation Basics.



Unification.



Unification Algorithm.



Managing Bindings.



Rules as Programs.



inside.



within.



yield and Backtracking.



Implementing Rules.



Implementing within.



Implementing Conjunctions.



Constructing within.



Compiling Facts.



Case Study.



14. Performance.


Fast Virtual Machines.



Garbage Collection Performance.



Implementing References.



Bytecode Optimization Techniques.



Warning.



Constant Propagation.



Strength Reduction.



Loop Unrolling.



Peephole Optimization.



Inlining.



Inlining Fields.



Separate Compilation.



15. Security and the Virtual Machine.


Java platform and Need for Security.



Security Promises of the JVM.



Security Architecture and Security Policy.



Example.



Basic Applet Security Policy.



More Sophisticated Policies.



Some Potential Attacks.



Implementation Details.



Protecting the Security Manager.



Bypassing Java Security.



Using Unconstructed Objects.



Invalid Casts.



Changing the Class of a Reference.



Reading Uninitialized Fields.



Array Bounds Checks.



Catching Exceptions.



Hidden Code.



Conclusion.



16. Threads and Synchronization.


Threads.



Example: Multithreaded Web Server.



Exceptions and Threads.



Sharing State Between Threads.



Need for Synchronization.



Exception: longs and doubles.



Monitors and Object Locks.



Synchronization in Java.



Synchronized Methods.



Scheduling.



Surrendering Control of the CPU.



Waiting for Another Thread.



Conclusion.


A. Tables.


Instructions by Opcode.



Instructions Alphabetically.



Instructions by Category.



Arithmetic.



Array.



Constant.



Control.



Data Type Conversion.



Object.



Stack Manipulation.



Synchronization.



Variable.



B. Oolong Reference.


Using the Oolong Assembler.



Gnoloo.



DumpClass.



Oolong Language.



Comments.



source.



class.



interface.



end class.



super.



implements.



field.



method.



limit locals.



limit stack.



line.



var.



throws.



catch.



end method.



Instructions.



Instructions with No Arguments.



Integers.



Labels.



Classes.



Fields and Methods.



invokeinterface.



multianewarray.



ldc, ldc_w, and ldc2_w.



newarray.



tableswitch.



lookupswitch.



C. Answers to Selected Exercises.


Further Readings.


Java and the JVM.


Newsgroup.


Other Languages.


Compilers.


Index. 0201309726T04062001