Java tutorial
/* * 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.commons.bcel6.classfile; import java.io.DataInput; import java.io.DataOutputStream; import java.io.IOException; import java.io.Serializable; import org.apache.commons.bcel6.Constants; /** * This class represents a local variable within a method. It contains its * scope, name, signature and index on the method's frame. * * @version $Id$ * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A> * @see LocalVariableTable */ public final class LocalVariable implements Constants, Cloneable, Node, Serializable { private static final long serialVersionUID = -51081099265972179L; private int start_pc; // Range in which the variable is valid private int length; private int name_index; // Index in constant pool of variable name private int signature_index; // Index of variable signature private int index; /* Variable is `index'th local variable on * this method's frame. */ private ConstantPool constant_pool; /** * Initialize from another object. Note that both objects use the same * references (shallow copy). Use copy() for a physical copy. */ public LocalVariable(LocalVariable c) { this(c.getStartPC(), c.getLength(), c.getNameIndex(), c.getSignatureIndex(), c.getIndex(), c.getConstantPool()); } /** * Construct object from file stream. * @param file Input stream * @throws IOException */ LocalVariable(DataInput file, ConstantPool constant_pool) throws IOException { this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), constant_pool); } /** * @param start_pc Range in which the variable * @param length ... is valid * @param name_index Index in constant pool of variable name * @param signature_index Index of variable's signature * @param index Variable is `index'th local variable on the method's frame * @param constant_pool Array of constants */ public LocalVariable(int start_pc, int length, int name_index, int signature_index, int index, ConstantPool constant_pool) { this.start_pc = start_pc; this.length = length; this.name_index = name_index; this.signature_index = signature_index; this.index = index; this.constant_pool = constant_pool; } /** * Called by objects that are traversing the nodes of the tree implicitely * 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 */ public void accept(Visitor v) { v.visitLocalVariable(this); } /** * Dump local variable to file stream in binary format. * * @param file Output file stream * @throws IOException */ public final void dump(DataOutputStream file) throws IOException { file.writeShort(start_pc); file.writeShort(length); file.writeShort(name_index); file.writeShort(signature_index); file.writeShort(index); } /** * @return Constant pool used by this object. */ public final ConstantPool getConstantPool() { return constant_pool; } /** * @return Variable is valid within getStartPC() .. getStartPC()+getLength() */ public final int getLength() { return length; } /** * @return Variable name. */ public final String getName() { ConstantUtf8 c; c = (ConstantUtf8) constant_pool.getConstant(name_index, CONSTANT_Utf8); return c.getBytes(); } /** * @return Index in constant pool of variable name. */ public final int getNameIndex() { return name_index; } /** * @return Signature. */ public final String getSignature() { ConstantUtf8 c; c = (ConstantUtf8) constant_pool.getConstant(signature_index, CONSTANT_Utf8); return c.getBytes(); } /** * @return Index in constant pool of variable signature. */ public final int getSignatureIndex() { return signature_index; } /** * @return index of register where variable is stored */ public final int getIndex() { return index; } /** * @return Start of range where he variable is valid */ public final int getStartPC() { return start_pc; } /** * @param constant_pool Constant pool to be used for this object. */ public final void setConstantPool(ConstantPool constant_pool) { this.constant_pool = constant_pool; } /** * @param length the length of this local variable */ public final void setLength(int length) { this.length = length; } /** * @param name_index the index into the constant pool for the name of this variable */ public final void setNameIndex(int name_index) { this.name_index = name_index; } /** * @param signature_index the index into the constant pool for the signature of this variable */ public final void setSignatureIndex(int signature_index) { this.signature_index = signature_index; } /** * @param index the index in the local variable table of this variable */ public final void setIndex(int index) { this.index = index; } /** * @param start_pc Specify range where the local variable is valid. */ public final void setStartPC(int start_pc) { this.start_pc = start_pc; } /** * @return string representation. */ @Override public final String toString() { String name = getName(), signature = Utility.signatureToString(getSignature()); return "LocalVariable(start_pc = " + start_pc + ", length = " + length + ", index = " + index + ":" + signature + " " + name + ")"; } /** * @return deep copy of this object */ public LocalVariable copy() { try { return (LocalVariable) clone(); } catch (CloneNotSupportedException e) { } return null; } }