src/com/sun/org/apache/bcel/internal/classfile/ConstantString.java

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package com.sun.org.apache.bcel.internal.classfile;

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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</A> class
 * and represents a reference to a String object.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @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);
  }
}