001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.bcel.classfile; 019 020import java.io.DataInput; 021import java.io.DataOutputStream; 022import java.io.IOException; 023 024import org.apache.bcel.Const; 025 026/** 027 * This class is derived from <em>Attribute</em> and represents a constant 028 * value, i.e., a default value for initializing a class field. 029 * This class is instantiated by the <em>Attribute.readAttribute()</em> method. 030 * 031 * @version $Id: ConstantValue.java 1749603 2016-06-21 20:50:19Z ggregory $ 032 * @see Attribute 033 */ 034public final class ConstantValue extends Attribute { 035 036 private int constantvalue_index; 037 038 039 /** 040 * Initialize from another object. Note that both objects use the same 041 * references (shallow copy). Use clone() for a physical copy. 042 */ 043 public ConstantValue(final ConstantValue c) { 044 this(c.getNameIndex(), c.getLength(), c.getConstantValueIndex(), c.getConstantPool()); 045 } 046 047 048 /** 049 * Construct object from input stream. 050 * @param name_index Name index in constant pool 051 * @param length Content length in bytes 052 * @param input Input stream 053 * @param constant_pool Array of constants 054 * @throws IOException 055 */ 056 ConstantValue(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) 057 throws IOException { 058 this(name_index, length, input.readUnsignedShort(), constant_pool); 059 } 060 061 062 /** 063 * @param name_index Name index in constant pool 064 * @param length Content length in bytes 065 * @param constantvalue_index Index in constant pool 066 * @param constant_pool Array of constants 067 */ 068 public ConstantValue(final int name_index, final int length, final int constantvalue_index, 069 final ConstantPool constant_pool) { 070 super(Const.ATTR_CONSTANT_VALUE, name_index, length, constant_pool); 071 this.constantvalue_index = constantvalue_index; 072 } 073 074 075 /** 076 * Called by objects that are traversing the nodes of the tree implicitely 077 * defined by the contents of a Java class. I.e., the hierarchy of methods, 078 * fields, attributes, etc. spawns a tree of objects. 079 * 080 * @param v Visitor object 081 */ 082 @Override 083 public void accept( final Visitor v ) { 084 v.visitConstantValue(this); 085 } 086 087 088 /** 089 * Dump constant value attribute to file stream on binary format. 090 * 091 * @param file Output file stream 092 * @throws IOException 093 */ 094 @Override 095 public final void dump( final DataOutputStream file ) throws IOException { 096 super.dump(file); 097 file.writeShort(constantvalue_index); 098 } 099 100 101 /** 102 * @return Index in constant pool of constant value. 103 */ 104 public final int getConstantValueIndex() { 105 return constantvalue_index; 106 } 107 108 109 /** 110 * @param constantvalue_index the index info the constant pool of this constant value 111 */ 112 public final void setConstantValueIndex( final int constantvalue_index ) { 113 this.constantvalue_index = constantvalue_index; 114 } 115 116 117 /** 118 * @return String representation of constant value. 119 */ 120 @Override 121 public final String toString() { 122 Constant c = super.getConstantPool().getConstant(constantvalue_index); 123 String buf; 124 int i; 125 // Print constant to string depending on its type 126 switch (c.getTag()) { 127 case Const.CONSTANT_Long: 128 buf = String.valueOf(((ConstantLong) c).getBytes()); 129 break; 130 case Const.CONSTANT_Float: 131 buf = String.valueOf(((ConstantFloat) c).getBytes()); 132 break; 133 case Const.CONSTANT_Double: 134 buf = String.valueOf(((ConstantDouble) c).getBytes()); 135 break; 136 case Const.CONSTANT_Integer: 137 buf = String.valueOf(((ConstantInteger) c).getBytes()); 138 break; 139 case Const.CONSTANT_String: 140 i = ((ConstantString) c).getStringIndex(); 141 c = super.getConstantPool().getConstant(i, Const.CONSTANT_Utf8); 142 buf = "\"" + Utility.convertString(((ConstantUtf8) c).getBytes()) + "\""; 143 break; 144 default: 145 throw new IllegalStateException("Type of ConstValue invalid: " + c); 146 } 147 return buf; 148 } 149 150 151 /** 152 * @return deep copy of this attribute 153 */ 154 @Override 155 public Attribute copy( final ConstantPool _constant_pool ) { 156 final ConstantValue c = (ConstantValue) clone(); 157 c.setConstantPool(_constant_pool); 158 return c; 159 } 160}