1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 package org.apache.bcel.classfile; 19 20 import java.io.DataInput; 21 import java.io.DataOutputStream; 22 import java.io.IOException; 23 24 import org.apache.bcel.Const; 25 26 /** 27 * This class is derived from <em>Attribute</em> and represents a constant 28 * value, i.e., a default value for initializing a class field. 29 * This class is instantiated by the <em>Attribute.readAttribute()</em> method. 30 * 31 * @version $Id$ 32 * @see Attribute 33 */ 34 public final class ConstantValue extends Attribute { 35 36 private int constantvalue_index; 37 38 39 /** 40 * Initialize from another object. Note that both objects use the same 41 * references (shallow copy). Use clone() for a physical copy. 42 */ ConstantValue(final ConstantValue c)43 public ConstantValue(final ConstantValue c) { 44 this(c.getNameIndex(), c.getLength(), c.getConstantValueIndex(), c.getConstantPool()); 45 } 46 47 48 /** 49 * Construct object from input stream. 50 * @param name_index Name index in constant pool 51 * @param length Content length in bytes 52 * @param input Input stream 53 * @param constant_pool Array of constants 54 * @throws IOException 55 */ ConstantValue(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)56 ConstantValue(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) 57 throws IOException { 58 this(name_index, length, input.readUnsignedShort(), constant_pool); 59 } 60 61 62 /** 63 * @param name_index Name index in constant pool 64 * @param length Content length in bytes 65 * @param constantvalue_index Index in constant pool 66 * @param constant_pool Array of constants 67 */ ConstantValue(final int name_index, final int length, final int constantvalue_index, final ConstantPool constant_pool)68 public ConstantValue(final int name_index, final int length, final int constantvalue_index, 69 final ConstantPool constant_pool) { 70 super(Const.ATTR_CONSTANT_VALUE, name_index, length, constant_pool); 71 this.constantvalue_index = constantvalue_index; 72 } 73 74 75 /** 76 * Called by objects that are traversing the nodes of the tree implicitely 77 * defined by the contents of a Java class. I.e., the hierarchy of methods, 78 * fields, attributes, etc. spawns a tree of objects. 79 * 80 * @param v Visitor object 81 */ 82 @Override accept( final Visitor v )83 public void accept( final Visitor v ) { 84 v.visitConstantValue(this); 85 } 86 87 88 /** 89 * Dump constant value attribute to file stream on binary format. 90 * 91 * @param file Output file stream 92 * @throws IOException 93 */ 94 @Override dump( final DataOutputStream file )95 public final void dump( final DataOutputStream file ) throws IOException { 96 super.dump(file); 97 file.writeShort(constantvalue_index); 98 } 99 100 101 /** 102 * @return Index in constant pool of constant value. 103 */ getConstantValueIndex()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 */ setConstantValueIndex( final int constantvalue_index )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 toString()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 copy( final ConstantPool _constant_pool )155 public Attribute copy( final ConstantPool _constant_pool ) { 156 final ConstantValue c = (ConstantValue) clone(); 157 c.setConstantPool(_constant_pool); 158 return c; 159 } 160 } 161