Field.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.bcel.classfile;
import java.io.DataInput;
import java.io.IOException;
import java.util.Objects;
import org.apache.bcel.Const;
import org.apache.bcel.generic.Type;
import org.apache.bcel.util.BCELComparator;
/**
* This class represents the field info structure, i.e., the representation for a variable in the class. See JVM
* specification for details.
*/
public final class Field extends FieldOrMethod {
/**
* Empty array constant.
*
* @since 6.6.0
*/
public static final Field[] EMPTY_ARRAY = {};
private static BCELComparator<Field> bcelComparator = new BCELComparator<Field>() {
@Override
public boolean equals(final Field a, final Field b) {
return a == b || a != null && b != null && Objects.equals(a.getName(), b.getName()) && Objects.equals(a.getSignature(), b.getSignature());
}
@Override
public int hashCode(final Field o) {
return o != null ? Objects.hash(o.getSignature(), o.getName()) : 0;
}
};
/**
* @return Comparison strategy object.
*/
public static BCELComparator<Field> getComparator() {
return bcelComparator;
}
/**
* @param comparator Comparison strategy object.
*/
public static void setComparator(final BCELComparator<Field> comparator) {
bcelComparator = comparator;
}
/**
* Constructs object from file stream.
*
* @param file Input stream.
*/
Field(final DataInput file, final ConstantPool constantPool) throws IOException, ClassFormatException {
super(file, constantPool);
}
/**
* Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
* physical copy.
*
* @param c Source to copy.
*/
public Field(final Field c) {
super(c);
}
/**
* @param accessFlags Access rights of field
* @param nameIndex Points to field name in constant pool
* @param signatureIndex Points to encoded signature
* @param attributes Collection of attributes
* @param constantPool Array of constants
*/
public Field(final int accessFlags, final int nameIndex, final int signatureIndex, final Attribute[] attributes, final ConstantPool constantPool) {
super(accessFlags, nameIndex, signatureIndex, attributes, constantPool);
}
/**
* Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
* I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
*
* @param v Visitor object
*/
@Override
public void accept(final Visitor v) {
v.visitField(this);
}
/**
* @return deep copy of this field
*/
public Field copy(final ConstantPool constantPool) {
return (Field) copy_(constantPool);
}
/**
* Return value as defined by given BCELComparator strategy. By default two Field objects are said to be equal when
* their names and signatures are equal.
*
* @see Object#equals(Object)
*/
@Override
public boolean equals(final Object obj) {
return obj instanceof Field && bcelComparator.equals(this, (Field) obj);
}
/**
* @return constant value associated with this field (may be null)
*/
public ConstantValue getConstantValue() {
for (final Attribute attribute : super.getAttributes()) {
if (attribute.getTag() == Const.ATTR_CONSTANT_VALUE) {
return (ConstantValue) attribute;
}
}
return null;
}
/**
* See https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.2.2
*
* @return type of field
*/
public Type getType() {
return Type.getType(getSignature());
}
/**
* Return value as defined by given BCELComparator strategy. By default return the hash code of the field's name XOR
* signature.
*
* @see Object#hashCode()
*/
@Override
public int hashCode() {
return bcelComparator.hashCode(this);
}
/**
* Return string representation close to declaration format, for example: 'public static final short MAX = 100'.
*
* @return String representation of field, including the signature.
*/
@Override
public String toString() {
String name;
String signature;
String access; // Short cuts to constant pool
// Get names from constant pool
access = Utility.accessToString(super.getAccessFlags());
access = access.isEmpty() ? "" : access + " ";
signature = Utility.signatureToString(getSignature());
name = getName();
final StringBuilder buf = new StringBuilder(64); // CHECKSTYLE IGNORE MagicNumber
buf.append(access).append(signature).append(" ").append(name);
final ConstantValue cv = getConstantValue();
if (cv != null) {
buf.append(" = ").append(cv);
}
for (final Attribute attribute : super.getAttributes()) {
if (!(attribute instanceof ConstantValue)) {
buf.append(" [").append(attribute).append("]");
}
}
return buf.toString();
}
}