Package com.sun.codemodel

Library for generating Java source code

See: Description

Interface Summary

Interface	Description
JAnnotatable	Annotatable program elements.
JAnnotationWriter<A extends Annotation>	Base interface for typed annotation writer.
JAssignmentTarget	Marker interface for code components that can be placed to the left of '=' in an assignment.
JClassContainer	The common aspect of a package and a class.
JDeclaration	Common interface for code components that can generate declarations of themselves.
JDocCommentable	Program elements that can have Javadoc
JExpression	A Java expression.
JGenerable	Common interface for code components that can generate uses of themselves.
JGenerifiable	Declarations that can have type variables.
JStatement	Common interface for code components that can generate uses of themselves as statements.

Class Summary

Class	Description
ClassType	This helps enable whether the JDefinedClass is a Class or Interface or AnnotationTypeDeclaration or Enum
CodeWriter	Receives generated code and writes to the appropriate storage.
JAnnotationArrayMember	Represents an arrays as annotation members
JAnnotationUse	Represents an annotation on a program element.
JAnnotationValue	Things that can be values of an annotation element.
JArray	array creation and initialization.
JAssignment	Assignment statements, which are also expressions.
JBlock	A block of Java code, which may contain statements and local declarations.
JCase	Case statement
JCatchBlock	Catch block for a try/catch/finally statement
JClass	Represents a Java reference type, such as a class, an interface, an enum, an array type, a parameterized type.
JCodeModel	Root of the code DOM.
JCommentPart	A part is a part of a javadoc comment, and it is a list of values.
JConditional	If statement, with optional else clause
JDefinedClass	A generated Java class/interface/enum/....
JDocComment	JavaDoc comment.
JDoLoop	Do loops
JEnumConstant	Enum Constant.
JExpr	Factory methods that generate various JExpressions.
JExpressionImpl	Provides default implementations for JExpression.
JFieldRef	Field Reference
JFieldVar	A field that can have a JDocComment associated with it
JForEach	ForEach Statement This will generate the code for statement based on the new j2se 1.5 j.l.s.
JForLoop	For statement
JFormatter	This is a utility class for managing indentation and other basic formatting for PrintWriter.
JInvocation	JMethod invocation
JJavaName	Utility methods that convert arbitrary strings into Java identifiers.
JLabel	Label that can be used for continue and break.
JMethod	Java method.
JMod	Modifier constants.
JMods	Modifier groups.
JNullType	Special class object that represents the type of "null".
JOp	JClass for generating expressions containing operators
JPackage	A Java package.
JPrimitiveType	Java built-in primitive types.
JResourceFile	Represents a resource file in the application-specific file format.
JStringLiteral	String literal.
JSwitch	Switch statement
JTryBlock	Try statement with Catch and/or Finally clause
JType	A representation of a type in codeModel.
JTypeVar	Type variable used to declare generics.
JVar	Variables and fields.
JWhileLoop	While statement

Exception Summary

Exception	Description
JClassAlreadyExistsException	Indicates that the class is already created.

Package com.sun.codemodel Description

Library for generating Java source code

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CodeModel is a library that allows you to generate Java source code in a type-safe fashion.

With CodeModel, you build the java source code by first building AST, then writing it out as text files that is Java source files. The AST looks like this:

You bulid this tree mostly from top-down. So, you first create a new JDefinedClass from JCodeModel, then you create a JMethod from JDefinedClass, and so on.

This design brings the following beneefits:

• source code can be written in random order
• generated source code nicely imports other classes
• generated source code is lexically always correct (no unbalanced parenthesis, etc.)
• code generation becomes relatively type-safe

The price you pay for that is increased memory footprint and the generation speed. See performance section for more discussions about the performance and possible improvements.

Using CodeModel

JCodeModel is the entry point to the library. See its javadoc for more details about how to use CodeModel.

Performance

Generally speaking, CodeModel is expected to be used in an environment where the resource constraint is not severe. Therefore, we haven't spent much effort in trying to make this library lean and mean.

That said, we did some benchmark and performance analysis. In case anyone is interested in making this library better performance wise, here's the findings.

Lists Maps, and other collections take up a lot of space. Allocating those things lazily is generally a good idea.

Compared to template-based code generator, the writing operation is slow, as it needs to traverse each AST node. Consider pre-encoding tokens (like 'public') to the target encoding, and consider exploting the subtree equivalence.