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Java example source code file (ConstantString.java)

This example Java source code file (ConstantString.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

constant, constantclass, constantobject, constantstring, identical, ioexception, string

The ConstantString.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal.classfile;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import  com.sun.org.apache.bcel.internal.Constants;
import  java.io.*;

/**
 * This class is derived from the abstract
 * <A HREF="com.sun.org.apache.bcel.internal.classfile.Constant.html">Constant class
 * and represents a reference to a String object.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 * @see     Constant
 */
public final class ConstantString extends Constant implements ConstantObject {
  private int string_index; // Identical to ConstantClass except for this name

  /**
   * Initialize from another object.
   */
  public ConstantString(ConstantString c) {
    this(c.getStringIndex());
  }
  /**
   * Initialize instance from file data.
   *
   * @param file Input stream
   * @throws IOException
   */
  ConstantString(DataInputStream file) throws IOException
  {
    this((int)file.readUnsignedShort());
  }
  /**
   * @param string_index Index of Constant_Utf8 in constant pool
   */
  public ConstantString(int string_index)
  {
    super(Constants.CONSTANT_String);
    this.string_index = string_index;
  }
  /**
   * Called by objects that are traversing the nodes of the tree implicitely
   * defined by the contents of a Java class. I.e., the hierarchy of methods,
   * fields, attributes, etc. spawns a tree of objects.
   *
   * @param v Visitor object
   */
  public void accept(Visitor v) {
    v.visitConstantString(this);
  }
  /**
   * Dump constant field reference to file stream in binary format.
   *
   * @param file Output file stream
   * @throws IOException
   */
  public final void dump(DataOutputStream file) throws IOException
  {
    file.writeByte(tag);
    file.writeShort(string_index);
  }
  /**
   * @return Index in constant pool of the string (ConstantUtf8).
   */
  public final int getStringIndex() { return string_index; }
  /**
   * @param string_index.
   */
  public final void setStringIndex(int string_index) {
    this.string_index = string_index;
  }
  /**
   * @return String representation.
   */
  public final String toString()
  {
    return super.toString() + "(string_index = " + string_index + ")";
  }

  /** @return String object
   */
  public Object getConstantValue(ConstantPool cp) {
    Constant c = cp.getConstant(string_index, Constants.CONSTANT_Utf8);
    return ((ConstantUtf8)c).getBytes();
  }

  /** @return dereferenced string
   */
  public String getBytes(ConstantPool cp) {
    return (String)getConstantValue(cp);
  }
}

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