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The JClass.java Java example source code
/*
* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.codemodel.internal;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* Represents a Java reference type, such as a class, an interface,
* an enum, an array type, a parameterized type.
*
* <p>
* To be exact, this object represents an "use" of a reference type,
* not necessarily a declaration of it, which is modeled as {@link JDefinedClass}.
*/
public abstract class JClass extends JType
{
protected JClass( JCodeModel _owner ) {
this._owner = _owner;
}
/**
* Gets the name of this class.
*
* @return
* name of this class, without any qualification.
* For example, this method returns "String" for
* <code>java.lang.String.
*/
abstract public String name();
/**
* Gets the package to which this class belongs.
* TODO: shall we move move this down?
*/
abstract public JPackage _package();
/**
* Returns the class in which this class is nested, or <tt>null if
* this is a top-level class.
*/
public JClass outer() {
return null;
}
private final JCodeModel _owner;
/** Gets the JCodeModel object to which this object belongs. */
public final JCodeModel owner() { return _owner; }
/**
* Gets the super class of this class.
*
* @return
* Returns the JClass representing the superclass of the
* entity (class or interface) represented by this {@link JClass}.
* Even if no super class is given explicitly or this {@link JClass}
* is not a class, this method still returns
* {@link JClass} for {@link Object}.
* If this JClass represents {@link Object}, return null.
*/
abstract public JClass _extends();
/**
* Iterates all super interfaces directly implemented by
* this class/interface.
*
* @return
* A non-null valid iterator that iterates all
* {@link JClass} objects that represents those interfaces
* implemented by this object.
*/
abstract public Iterator<JClass> _implements();
/**
* Iterates all the type parameters of this class/interface.
*
* <p>
* For example, if this {@link JClass} represents
* <code>Set<T>, this method returns an array
* that contains single {@link JTypeVar} for 'T'.
*/
public JTypeVar[] typeParams() {
return EMPTY_ARRAY;
}
/**
* Sometimes useful reusable empty array.
*/
protected static final JTypeVar[] EMPTY_ARRAY = new JTypeVar[0];
/**
* Checks if this object represents an interface.
*/
abstract public boolean isInterface();
/**
* Checks if this class is an abstract class.
*/
abstract public boolean isAbstract();
/**
* If this class represents one of the wrapper classes
* defined in the java.lang package, return the corresponding
* primitive type. Otherwise null.
*/
public JPrimitiveType getPrimitiveType() { return null; }
/**
* @deprecated calling this method from {@link JClass}
* would be meaningless, since it's always guaranteed to
* return <tt>this.
*/
public JClass boxify() { return this; }
public JType unboxify() {
JPrimitiveType pt = getPrimitiveType();
return pt==null ? (JType)this : pt;
}
public JClass erasure() {
return this;
}
/**
* Checks the relationship between two classes.
* <p>
* This method works in the same way as {@link Class#isAssignableFrom(Class)}
* works. For example, baseClass.isAssignableFrom(derivedClass)==true.
*/
public final boolean isAssignableFrom( JClass derived ) {
// to avoid the confusion, always use "this" explicitly in this method.
// null can be assigned to any type.
if( derived instanceof JNullType ) return true;
if( this==derived ) return true;
// the only class that is assignable from an interface is
// java.lang.Object
if( this==_package().owner().ref(Object.class) ) return true;
JClass b = derived._extends();
if( b!=null && this.isAssignableFrom(b) )
return true;
if( this.isInterface() ) {
Iterator<JClass> itfs = derived._implements();
while( itfs.hasNext() )
if( this.isAssignableFrom(itfs.next()) )
return true;
}
return false;
}
/**
* Gets the parameterization of the given base type.
*
* <p>
* For example, given the following
* <pre><![CDATA[
* interface Foo<T> extends List<List<T>> {}
* interface Bar extends Foo<String> {}
* </xmp></pre>
* This method works like this:
* <pre><xmp>
* getBaseClass( Bar, List ) = List<List<String>
* getBaseClass( Bar, Foo ) = Foo<String>
* getBaseClass( Foo<? extends Number>, Collection ) = Collection<List<? extends Number>>
* getBaseClass( ArrayList<? extends BigInteger>, List ) = List<? extends BigInteger>
* </xmp></pre>
*
* @param baseType
* The class whose parameterization we are interested in.
* @return
* The use of {@code baseType} in {@code this} type.
* or null if the type is not assignable to the base type.
*/
public final JClass getBaseClass( JClass baseType ) {
if( this.erasure().equals(baseType) )
return this;
JClass b = _extends();
if( b!=null ) {
JClass bc = b.getBaseClass(baseType);
if(bc!=null)
return bc;
}
Iterator<JClass> itfs = _implements();
while( itfs.hasNext() ) {
JClass bc = itfs.next().getBaseClass(baseType);
if(bc!=null)
return bc;
}
return null;
}
public final JClass getBaseClass( Class<?> baseType ) {
return getBaseClass(owner().ref(baseType));
}
private JClass arrayClass;
public JClass array() {
if(arrayClass==null)
arrayClass = new JArrayClass(owner(),this);
return arrayClass;
}
/**
* "Narrows" a generic class to a concrete class by specifying
* a type argument.
*
* <p>
* <code>.narrow(X)</code> builds <code>Set<X></code> from <code>Set</code>.
*/
public JClass narrow( Class<?> clazz ) {
return narrow(owner().ref(clazz));
}
public JClass narrow( Class<?>... clazz ) {
JClass[] r = new JClass[clazz.length];
for( int i=0; i<clazz.length; i++ )
r[i] = owner().ref(clazz[i]);
return narrow(r);
}
/**
* "Narrows" a generic class to a concrete class by specifying
* a type argument.
*
* <p>
* <code>.narrow(X)</code> builds <code>Set<X></code> from <code>Set</code>.
*/
public JClass narrow( JClass clazz ) {
return new JNarrowedClass(this,clazz);
}
public JClass narrow( JType type ) {
return narrow(type.boxify());
}
public JClass narrow( JClass... clazz ) {
return new JNarrowedClass(this,Arrays.asList(clazz.clone()));
}
public JClass narrow( List<? extends JClass> clazz ) {
return new JNarrowedClass(this,new ArrayList<JClass>(clazz));
}
/**
* If this class is parameterized, return the type parameter of the given index.
*/
public List<JClass> getTypeParameters() {
return Collections.emptyList();
}
/**
* Returns true if this class is a parameterized class.
*/
public final boolean isParameterized() {
return erasure()!=this;
}
/**
* Create "? extends T" from T.
*
* @return never null
*/
public final JClass wildcard() {
return new JTypeWildcard(this);
}
/**
* Substitutes the type variables with their actual arguments.
*
* <p>
* For example, when this class is Map<String,Map<V>>,
* (where V then doing
* substituteParams( V, Integer ) returns a {@link JClass}
* for <code>Map<String,Map<Integer>></code>.
*
* <p>
* This method needs to work recursively.
*/
protected abstract JClass substituteParams( JTypeVar[] variables, List<JClass> bindings );
public String toString() {
return this.getClass().getName() + '(' + name() + ')';
}
public final JExpression dotclass() {
return JExpr.dotclass(this);
}
/** Generates a static method invocation. */
public final JInvocation staticInvoke(JMethod method) {
return new JInvocation(this,method);
}
/** Generates a static method invocation. */
public final JInvocation staticInvoke(String method) {
return new JInvocation(this,method);
}
/** Static field reference. */
public final JFieldRef staticRef(String field) {
return new JFieldRef(this, field);
}
/** Static field reference. */
public final JFieldRef staticRef(JVar field) {
return new JFieldRef(this, field);
}
public void generate(JFormatter f) {
f.t(this);
}
/**
* Prints the class name in javadoc @link format.
*/
void printLink(JFormatter f) {
f.p("{@link ").g(this).p('}');
}
}
</pre>
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