< prev index next >

src/java.base/share/classes/java/lang/constant/ClassDesc.java

Print this page

 40  * A <a href="package-summary.html#nominal">nominal descriptor</a> for a
 41  * {@link Class} constant.
 42  *
 43  * <p>For common system types, including all the primitive types, there are
 44  * predefined {@linkplain ClassDesc} constants in {@link ConstantDescs}.
 45  * (The {@code java.lang.constant} APIs consider {@code void} to be a primitive type.)
 46  * To create a {@linkplain ClassDesc} for a class or interface type, use {@link #of} or
 47  * {@link #ofDescriptor(String)}; to create a {@linkplain ClassDesc} for an array
 48  * type, use {@link #ofDescriptor(String)}, or first obtain a
 49  * {@linkplain ClassDesc} for the component type and then call the {@link #arrayType()}
 50  * or {@link #arrayType(int)} methods.
 51  *
 52  * @see ConstantDescs
 53  *
 54  * @since 12
 55  */
 56 public sealed interface ClassDesc
 57         extends ConstantDesc,
 58                 TypeDescriptor.OfField<ClassDesc>
 59         permits PrimitiveClassDescImpl,
 60                 ReferenceClassDescImpl {
 61 
 62     /**
 63      * Returns a {@linkplain ClassDesc} for a class or interface type,
 64      * given the name of the class or interface, such as {@code "java.lang.String"}.
 65      * (To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
 66      * or {@link #arrayType()}; to create a descriptor for a primitive type, use
 67      * {@link #ofDescriptor(String)} or use the predefined constants in
 68      * {@link ConstantDescs}).
 69      *
 70      * @param name the fully qualified (dot-separated) binary class name
 71      * @return a {@linkplain ClassDesc} describing the desired class
 72      * @throws NullPointerException if the argument is {@code null}
 73      * @throws IllegalArgumentException if the name string is not in the
 74      * correct format
 75      * @see ClassDesc#ofDescriptor(String)
 76      * @see ClassDesc#ofInternalName(String)
 77      */
 78     static ClassDesc of(String name) {
 79         ConstantUtils.validateBinaryClassName(requireNonNull(name));
 80         return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");

152      * correct format
153      * @jvms 4.3.2 Field Descriptors
154      * @jvms 4.4.1 The CONSTANT_Class_info Structure
155      * @see ClassDesc#of(String)
156      * @see ClassDesc#ofInternalName(String)
157      */
158     static ClassDesc ofDescriptor(String descriptor) {
159         requireNonNull(descriptor);
160         if (descriptor.isEmpty()) {
161             throw new IllegalArgumentException(
162                     "not a valid reference type descriptor: " + descriptor);
163         }
164         int depth = ConstantUtils.arrayDepth(descriptor);
165         if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
166             throw new IllegalArgumentException(
167                     "Cannot create an array type descriptor with more than " +
168                     ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
169         }
170         return (descriptor.length() == 1)
171                ? new PrimitiveClassDescImpl(descriptor)
172                : new ReferenceClassDescImpl(descriptor);
173     }
174 
175     /**
176      * Returns a {@linkplain ClassDesc} for an array type whose component type
177      * is described by this {@linkplain ClassDesc}.
178      *
179      * @return a {@linkplain ClassDesc} describing the array type
180      * @throws IllegalStateException if the resulting {@linkplain
181      * ClassDesc} would have an array rank of greater than 255
182      * @jvms 4.4.1 The CONSTANT_Class_info Structure
183      */
184     default ClassDesc arrayType() {
185         int depth = ConstantUtils.arrayDepth(descriptorString());
186         if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
187             throw new IllegalStateException(
188                     "Cannot create an array type descriptor with more than " +
189                     ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
190         }
191         return arrayType(1);
192     }

278      */
279     default boolean isArray() {
280         return descriptorString().startsWith("[");
281     }
282 
283     /**
284      * Returns whether this {@linkplain ClassDesc} describes a primitive type.
285      *
286      * @return whether this {@linkplain ClassDesc} describes a primitive type
287      */
288     default boolean isPrimitive() {
289         return descriptorString().length() == 1;
290     }
291 
292     /**
293      * Returns whether this {@linkplain ClassDesc} describes a class or interface type.
294      *
295      * @return whether this {@linkplain ClassDesc} describes a class or interface type
296      */
297     default boolean isClassOrInterface() {
298         return descriptorString().startsWith("L");
299     }
300 
301     /**
302      * Returns the component type of this {@linkplain ClassDesc}, if it describes
303      * an array type, or {@code null} otherwise.
304      *
305      * @return a {@linkplain ClassDesc} describing the component type, or {@code null}
306      * if this descriptor does not describe an array type
307      */
308     default ClassDesc componentType() {
309         return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
310     }
311 
312     /**
313      * Returns the package name of this {@linkplain ClassDesc}, if it describes
314      * a class or interface type.
315      *
316      * @return the package name, or the empty string if the class is in the
317      * default package, or this {@linkplain ClassDesc} does not describe a class or interface type
318      */

 40  * A <a href="package-summary.html#nominal">nominal descriptor</a> for a
 41  * {@link Class} constant.
 42  *
 43  * <p>For common system types, including all the primitive types, there are
 44  * predefined {@linkplain ClassDesc} constants in {@link ConstantDescs}.
 45  * (The {@code java.lang.constant} APIs consider {@code void} to be a primitive type.)
 46  * To create a {@linkplain ClassDesc} for a class or interface type, use {@link #of} or
 47  * {@link #ofDescriptor(String)}; to create a {@linkplain ClassDesc} for an array
 48  * type, use {@link #ofDescriptor(String)}, or first obtain a
 49  * {@linkplain ClassDesc} for the component type and then call the {@link #arrayType()}
 50  * or {@link #arrayType(int)} methods.
 51  *
 52  * @see ConstantDescs
 53  *
 54  * @since 12
 55  */
 56 public sealed interface ClassDesc
 57         extends ConstantDesc,
 58                 TypeDescriptor.OfField<ClassDesc>
 59         permits PrimitiveClassDescImpl,
 60                 ClassDescImpl {
 61 
 62     /**
 63      * Returns a {@linkplain ClassDesc} for a class or interface type,
 64      * given the name of the class or interface, such as {@code "java.lang.String"}.
 65      * (To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
 66      * or {@link #arrayType()}; to create a descriptor for a primitive type, use
 67      * {@link #ofDescriptor(String)} or use the predefined constants in
 68      * {@link ConstantDescs}).
 69      *
 70      * @param name the fully qualified (dot-separated) binary class name
 71      * @return a {@linkplain ClassDesc} describing the desired class
 72      * @throws NullPointerException if the argument is {@code null}
 73      * @throws IllegalArgumentException if the name string is not in the
 74      * correct format
 75      * @see ClassDesc#ofDescriptor(String)
 76      * @see ClassDesc#ofInternalName(String)
 77      */
 78     static ClassDesc of(String name) {
 79         ConstantUtils.validateBinaryClassName(requireNonNull(name));
 80         return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");

152      * correct format
153      * @jvms 4.3.2 Field Descriptors
154      * @jvms 4.4.1 The CONSTANT_Class_info Structure
155      * @see ClassDesc#of(String)
156      * @see ClassDesc#ofInternalName(String)
157      */
158     static ClassDesc ofDescriptor(String descriptor) {
159         requireNonNull(descriptor);
160         if (descriptor.isEmpty()) {
161             throw new IllegalArgumentException(
162                     "not a valid reference type descriptor: " + descriptor);
163         }
164         int depth = ConstantUtils.arrayDepth(descriptor);
165         if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
166             throw new IllegalArgumentException(
167                     "Cannot create an array type descriptor with more than " +
168                     ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
169         }
170         return (descriptor.length() == 1)
171                ? new PrimitiveClassDescImpl(descriptor)
172                : new ClassDescImpl(descriptor);
173     }
174 
175     /**
176      * Returns a {@linkplain ClassDesc} for an array type whose component type
177      * is described by this {@linkplain ClassDesc}.
178      *
179      * @return a {@linkplain ClassDesc} describing the array type
180      * @throws IllegalStateException if the resulting {@linkplain
181      * ClassDesc} would have an array rank of greater than 255
182      * @jvms 4.4.1 The CONSTANT_Class_info Structure
183      */
184     default ClassDesc arrayType() {
185         int depth = ConstantUtils.arrayDepth(descriptorString());
186         if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
187             throw new IllegalStateException(
188                     "Cannot create an array type descriptor with more than " +
189                     ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
190         }
191         return arrayType(1);
192     }

278      */
279     default boolean isArray() {
280         return descriptorString().startsWith("[");
281     }
282 
283     /**
284      * Returns whether this {@linkplain ClassDesc} describes a primitive type.
285      *
286      * @return whether this {@linkplain ClassDesc} describes a primitive type
287      */
288     default boolean isPrimitive() {
289         return descriptorString().length() == 1;
290     }
291 
292     /**
293      * Returns whether this {@linkplain ClassDesc} describes a class or interface type.
294      *
295      * @return whether this {@linkplain ClassDesc} describes a class or interface type
296      */
297     default boolean isClassOrInterface() {
298         return descriptorString().startsWith("L") || descriptorString().startsWith("Q");
299     }
300 
301     /**
302      * Returns the component type of this {@linkplain ClassDesc}, if it describes
303      * an array type, or {@code null} otherwise.
304      *
305      * @return a {@linkplain ClassDesc} describing the component type, or {@code null}
306      * if this descriptor does not describe an array type
307      */
308     default ClassDesc componentType() {
309         return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
310     }
311 
312     /**
313      * Returns the package name of this {@linkplain ClassDesc}, if it describes
314      * a class or interface type.
315      *
316      * @return the package name, or the empty string if the class is in the
317      * default package, or this {@linkplain ClassDesc} does not describe a class or interface type
318      */
< prev index next >