1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.bcel.internal.classfile;
  23 
  24 import java.io.DataInput;
  25 import java.io.DataOutputStream;
  26 import java.io.IOException;
  27 
  28 import com.sun.org.apache.bcel.internal.Const;
  29 
  30 /**
  31  * This class is derived from the abstract {@link Constant}
  32  * and represents a reference to a String object.
  33  *
  34  * @version $Id$
  35  * @see     Constant
  36  */
  37 public final class ConstantString extends Constant implements ConstantObject {
  38 
  39     private int string_index; // Identical to ConstantClass except for this name
  40 
  41 
  42     /**
  43      * Initialize from another object.
  44      */
  45     public ConstantString(final ConstantString c) {
  46         this(c.getStringIndex());
  47     }
  48 
  49 
  50     /**
  51      * Initialize instance from file data.
  52      *
  53      * @param file Input stream
  54      * @throws IOException
  55      */
  56     ConstantString(final DataInput file) throws IOException {
  57         this(file.readUnsignedShort());
  58     }
  59 
  60 
  61     /**
  62      * @param string_index Index of Constant_Utf8 in constant pool
  63      */
  64     public ConstantString(final int string_index) {
  65         super(Const.CONSTANT_String);
  66         this.string_index = string_index;
  67     }
  68 
  69 
  70     /**
  71      * Called by objects that are traversing the nodes of the tree implicitely
  72      * defined by the contents of a Java class. I.e., the hierarchy of methods,
  73      * fields, attributes, etc. spawns a tree of objects.
  74      *
  75      * @param v Visitor object
  76      */
  77     @Override
  78     public void accept( final Visitor v ) {
  79         v.visitConstantString(this);
  80     }
  81 
  82 
  83     /**
  84      * Dump constant field reference to file stream in binary format.
  85      *
  86      * @param file Output file stream
  87      * @throws IOException
  88      */
  89     @Override
  90     public final void dump( final DataOutputStream file ) throws IOException {
  91         file.writeByte(super.getTag());
  92         file.writeShort(string_index);
  93     }
  94 
  95 
  96     /**
  97      * @return Index in constant pool of the string (ConstantUtf8).
  98      */
  99     public final int getStringIndex() {
 100         return string_index;
 101     }
 102 
 103 
 104     /**
 105      * @param string_index the index into the constant of the string value
 106      */
 107     public final void setStringIndex( final int string_index ) {
 108         this.string_index = string_index;
 109     }
 110 
 111 
 112     /**
 113      * @return String representation.
 114      */
 115     @Override
 116     public final String toString() {
 117         return super.toString() + "(string_index = " + string_index + ")";
 118     }
 119 
 120 
 121     /** @return String object
 122      */
 123     @Override
 124     public Object getConstantValue( final ConstantPool cp ) {
 125         final Constant c = cp.getConstant(string_index, Const.CONSTANT_Utf8);
 126         return ((ConstantUtf8) c).getBytes();
 127     }
 128 
 129 
 130     /** @return dereferenced string
 131      */
 132     public String getBytes( final ConstantPool cp ) {
 133         return (String) getConstantValue(cp);
 134     }
 135 }