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 the abstract {@link Constant} 28 * and represents a reference to a (external) class. 29 * 30 * @version $Id$ 31 * @see Constant 32 */ 33 public final class ConstantClass extends Constant implements ConstantObject { 34 35 private int name_index; // Identical to ConstantString except for the name 36 37 38 /** 39 * Initialize from another object. 40 */ 41 public ConstantClass(final ConstantClass c) { 42 this(c.getNameIndex()); 43 } 44 45 46 /** 47 * Initialize instance from file data. 48 * 49 * @param file Input stream 50 * @throws IOException 51 */ 52 ConstantClass(final DataInput file) throws IOException { 53 this(file.readUnsignedShort()); 54 } 55 56 57 /** 58 * @param name_index Name index in constant pool. Should refer to a 59 * ConstantUtf8. 60 */ 61 public ConstantClass(final int name_index) { 62 super(Const.CONSTANT_Class); 63 this.name_index = name_index; 64 } 65 66 67 /** 68 * Called by objects that are traversing the nodes of the tree implicitely 69 * defined by the contents of a Java class. I.e., the hierarchy of methods, 70 * fields, attributes, etc. spawns a tree of objects. 71 * 72 * @param v Visitor object 73 */ 74 @Override 75 public void accept( final Visitor v ) { 76 v.visitConstantClass(this); 77 } 78 79 80 /** 81 * Dump constant class to file stream in binary format. 82 * 83 * @param file Output file stream 84 * @throws IOException 85 */ 86 @Override 87 public final void dump( final DataOutputStream file ) throws IOException { 88 file.writeByte(super.getTag()); 89 file.writeShort(name_index); 90 } 91 92 93 /** 94 * @return Name index in constant pool of class name. 95 */ 96 public final int getNameIndex() { 97 return name_index; 98 } 99 100 101 /** 102 * @param name_index the name index in the constant pool of this Constant Class 103 */ 104 public final void setNameIndex( final int name_index ) { 105 this.name_index = name_index; 106 } 107 108 109 /** @return String object 110 */ 111 @Override 112 public Object getConstantValue( final ConstantPool cp ) { 113 final Constant c = cp.getConstant(name_index, Const.CONSTANT_Utf8); 114 return ((ConstantUtf8) c).getBytes(); 115 } 116 117 118 /** @return dereferenced string 119 */ 120 public String getBytes( final ConstantPool cp ) { 121 return (String) getConstantValue(cp); 122 } 123 124 125 /** 126 * @return String representation. 127 */ 128 @Override 129 public final String toString() { 130 return super.toString() + "(name_index = " + name_index + ")"; 131 } 132 } 133