Java example source code file (Annotation.java)

This example Java source code file (Annotation.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation_element_value, array_element_value, class_element_value, enum_element_value, invalidannotation, ioexception, override, primitive_element_value, r\,p

The Annotation.java Java example source code

/*
 * Copyright (c) 2007, 2009, 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.tools.classfile;

import java.io.IOException;

/**
 * See JVMS, section 4.8.16.
 *
 *  <p>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public class Annotation {
    static class InvalidAnnotation extends AttributeException {
        private static final long serialVersionUID = -4620480740735772708L;
        InvalidAnnotation(String msg) {
            super(msg);
        }
    }

    Annotation(ClassReader cr) throws IOException, InvalidAnnotation {
        type_index = cr.readUnsignedShort();
        num_element_value_pairs = cr.readUnsignedShort();
        element_value_pairs = new element_value_pair[num_element_value_pairs];
        for (int i = 0; i < element_value_pairs.length; i++)
            element_value_pairs[i] = new element_value_pair(cr);
    }

    public Annotation(ConstantPool constant_pool,
            int type_index,
            element_value_pair[] element_value_pairs) {
        this.type_index = type_index;
        num_element_value_pairs = element_value_pairs.length;
        this.element_value_pairs = element_value_pairs;
    }

    public int length() {
        int n = 2 /*type_index*/ + 2 /*num_element_value_pairs*/;
        for (element_value_pair pair: element_value_pairs)
            n += pair.length();
        return n;
    }

    public final int type_index;
    public final int num_element_value_pairs;
    public final element_value_pair element_value_pairs[];

    /**
     * See JVMS, section 4.8.16.1.
     */
    public static abstract class element_value {
        public static element_value read(ClassReader cr)
                throws IOException, InvalidAnnotation {
            int tag = cr.readUnsignedByte();
            switch (tag) {
            case 'B':
            case 'C':
            case 'D':
            case 'F':
            case 'I':
            case 'J':
            case 'S':
            case 'Z':
            case 's':
                return new Primitive_element_value(cr, tag);

            case 'e':
                return new Enum_element_value(cr, tag);

            case 'c':
                return new Class_element_value(cr, tag);

            case '@':
                return new Annotation_element_value(cr, tag);

            case '[':
                return new Array_element_value(cr, tag);

            default:
                throw new InvalidAnnotation("unrecognized tag: " + tag);
            }
        }

        protected element_value(int tag) {
            this.tag = tag;
        }

        public abstract int length();

        public abstract <R,P> R accept(Visitor visitor, P p);

        public interface Visitor<R,P> {
            R visitPrimitive(Primitive_element_value ev, P p);
            R visitEnum(Enum_element_value ev, P p);
            R visitClass(Class_element_value ev, P p);
            R visitAnnotation(Annotation_element_value ev, P p);
            R visitArray(Array_element_value ev, P p);
        }

        public final int tag;
    }

    public static class Primitive_element_value extends element_value {
        Primitive_element_value(ClassReader cr, int tag) throws IOException {
            super(tag);
            const_value_index = cr.readUnsignedShort();
        }

        @Override
        public int length() {
            return 2;
        }

        public <R,P> R accept(Visitor visitor, P p) {
            return visitor.visitPrimitive(this, p);
        }

        public final int const_value_index;

    }

    public static class Enum_element_value extends element_value {
        Enum_element_value(ClassReader cr, int tag) throws IOException {
            super(tag);
            type_name_index = cr.readUnsignedShort();
            const_name_index = cr.readUnsignedShort();
        }

        @Override
        public int length() {
            return 4;
        }

        public <R,P> R accept(Visitor visitor, P p) {
            return visitor.visitEnum(this, p);
        }

        public final int type_name_index;
        public final int const_name_index;
    }

    public static class Class_element_value extends element_value {
        Class_element_value(ClassReader cr, int tag) throws IOException {
            super(tag);
            class_info_index = cr.readUnsignedShort();
        }

        @Override
        public int length() {
            return 2;
        }

        public <R,P> R accept(Visitor visitor, P p) {
            return visitor.visitClass(this, p);
        }

        public final int class_info_index;
    }

    public static class Annotation_element_value extends element_value {
        Annotation_element_value(ClassReader cr, int tag)
                throws IOException, InvalidAnnotation {
            super(tag);
            annotation_value = new Annotation(cr);
        }

        @Override
        public int length() {
            return annotation_value.length();
        }

        public <R,P> R accept(Visitor visitor, P p) {
            return visitor.visitAnnotation(this, p);
        }

        public final Annotation annotation_value;
    }

    public static class Array_element_value extends element_value {
        Array_element_value(ClassReader cr, int tag)
                throws IOException, InvalidAnnotation {
            super(tag);
            num_values = cr.readUnsignedShort();
            values = new element_value[num_values];
            for (int i = 0; i < values.length; i++)
                values[i] = element_value.read(cr);
        }

        @Override
        public int length() {
            int n = 2;
            for (int i = 0; i < values.length; i++)
                n += values[i].length();
            return n;
        }

        public <R,P> R accept(Visitor visitor, P p) {
            return visitor.visitArray(this, p);
        }

        public final int num_values;
        public final element_value[] values;
    }

    public static class element_value_pair {
        element_value_pair(ClassReader cr)
                throws IOException, InvalidAnnotation {
            element_name_index = cr.readUnsignedShort();
            value = element_value.read(cr);
        }

        public int length() {
            return 2 + value.length();
        }

        public final int element_name_index;
        public final element_value value;
    }
}