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.IOException; 022import java.util.Objects; 023 024import org.apache.bcel.Const; 025import org.apache.bcel.generic.Type; 026import org.apache.bcel.util.BCELComparator; 027 028/** 029 * This class represents the field info structure, i.e., the representation 030 * for a variable in the class. See JVM specification for details. 031 * 032 * @version $Id$ 033 */ 034public final class Field extends FieldOrMethod { 035 036 private static BCELComparator bcelComparator = new BCELComparator() { 037 038 @Override 039 public boolean equals( final Object o1, final Object o2 ) { 040 final Field THIS = (Field) o1; 041 final Field THAT = (Field) o2; 042 return Objects.equals(THIS.getName(), THAT.getName()) 043 && Objects.equals(THIS.getSignature(), THAT.getSignature()); 044 } 045 046 047 @Override 048 public int hashCode( final Object o ) { 049 final Field THIS = (Field) o; 050 return THIS.getSignature().hashCode() ^ THIS.getName().hashCode(); 051 } 052 }; 053 054 055 /** 056 * Initialize from another object. Note that both objects use the same 057 * references (shallow copy). Use clone() for a physical copy. 058 */ 059 public Field(final Field c) { 060 super(c); 061 } 062 063 064 /** 065 * Construct object from file stream. 066 * @param file Input stream 067 */ 068 Field(final DataInput file, final ConstantPool constant_pool) throws IOException, 069 ClassFormatException { 070 super(file, constant_pool); 071 } 072 073 074 /** 075 * @param access_flags Access rights of field 076 * @param name_index Points to field name in constant pool 077 * @param signature_index Points to encoded signature 078 * @param attributes Collection of attributes 079 * @param constant_pool Array of constants 080 */ 081 public Field(final int access_flags, final int name_index, final int signature_index, final Attribute[] attributes, 082 final ConstantPool constant_pool) { 083 super(access_flags, name_index, signature_index, attributes, constant_pool); 084 } 085 086 087 /** 088 * Called by objects that are traversing the nodes of the tree implicitely 089 * defined by the contents of a Java class. I.e., the hierarchy of methods, 090 * fields, attributes, etc. spawns a tree of objects. 091 * 092 * @param v Visitor object 093 */ 094 @Override 095 public void accept( final Visitor v ) { 096 v.visitField(this); 097 } 098 099 100 /** 101 * @return constant value associated with this field (may be null) 102 */ 103 public final ConstantValue getConstantValue() { 104 for (final Attribute attribute : super.getAttributes()) { 105 if (attribute.getTag() == Const.ATTR_CONSTANT_VALUE) { 106 return (ConstantValue) attribute; 107 } 108 } 109 return null; 110 } 111 112 113 /** 114 * Return string representation close to declaration format, 115 * `public static final short MAX = 100', e.g.. 116 * 117 * @return String representation of field, including the signature. 118 */ 119 @Override 120 public final String toString() { 121 String name; 122 String signature; 123 String access; // Short cuts to constant pool 124 125 // Get names from constant pool 126 access = Utility.accessToString(super.getAccessFlags()); 127 access = access.isEmpty() ? "" : (access + " "); 128 signature = Utility.signatureToString(getSignature()); 129 name = getName(); 130 final StringBuilder buf = new StringBuilder(64); // CHECKSTYLE IGNORE MagicNumber 131 buf.append(access).append(signature).append(" ").append(name); 132 final ConstantValue cv = getConstantValue(); 133 if (cv != null) { 134 buf.append(" = ").append(cv); 135 } 136 for (final Attribute attribute : super.getAttributes()) { 137 if (!(attribute instanceof ConstantValue)) { 138 buf.append(" [").append(attribute).append("]"); 139 } 140 } 141 return buf.toString(); 142 } 143 144 145 /** 146 * @return deep copy of this field 147 */ 148 public final Field copy( final ConstantPool _constant_pool ) { 149 return (Field) copy_(_constant_pool); 150 } 151 152 153 /** 154 * @return type of field 155 */ 156 public Type getType() { 157 return Type.getReturnType(getSignature()); 158 } 159 160 161 /** 162 * @return Comparison strategy object 163 */ 164 public static BCELComparator getComparator() { 165 return bcelComparator; 166 } 167 168 169 /** 170 * @param comparator Comparison strategy object 171 */ 172 public static void setComparator( final BCELComparator comparator ) { 173 bcelComparator = comparator; 174 } 175 176 177 /** 178 * Return value as defined by given BCELComparator strategy. 179 * By default two Field objects are said to be equal when 180 * their names and signatures are equal. 181 * 182 * @see java.lang.Object#equals(java.lang.Object) 183 */ 184 @Override 185 public boolean equals( final Object obj ) { 186 return bcelComparator.equals(this, obj); 187 } 188 189 190 /** 191 * Return value as defined by given BCELComparator strategy. 192 * By default return the hashcode of the field's name XOR signature. 193 * 194 * @see java.lang.Object#hashCode() 195 */ 196 @Override 197 public int hashCode() { 198 return bcelComparator.hashCode(this); 199 } 200}