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