Apache BCEL Source Code Files are inside the Apache BCEL source package file like bcel-6.5.0-src.zip. Unzip the source package file and go to the "src/main" sub-directory, you will see source code files.

Here is the list of Java source code files of the Apache BCEL 6.5.0 in \Users\fyicenter\bcel-6.5.0\src:

⏎ org/apache/bcel/verifier/statics/IntList.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.verifier.statics;


import java.util.ArrayList;
import java.util.List;

/**
 * A small utility class representing a set of basic int values.
 *
 */
public class IntList{
    /** The int are stored as Integer objects here. */
    private final List<Integer> theList;
    /** This constructor creates an empty list. */
    IntList() {
        theList = new ArrayList<>();
    }
    /** Adds an element to the list. */
    void add(final int i) {
        theList.add(Integer.valueOf(i));
    }
    /** Checks if the specified int is already in the list. */
    boolean contains(final int i) {
        final Integer[] ints = new Integer[theList.size()];
        theList.toArray(ints);
        for (final Integer k : ints) {
            if (i == k.intValue()) {
                return true;
            }
        }
        return false;
    }
}

⏎ org/apache/bcel/verifier/statics/IntList.java

Or download all of them as a single archive file:

File name: bcel-6.5.0-fyi.zip
File size: 706792 bytes
Release date: 2020-07-03
Download 

⇒ JDK "javap" Command

⇐ Install Apache BCEL 6.5.0 Binary Package

⇑ Apache BCEL (Byte Code Engineering Library)

⇑⇑ Java Bytecode Tools