JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the com.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ com/sun/org/apache/xerces/internal/impl/xs/util/ObjectListImpl.java

/*
 * Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * 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 com.sun.org.apache.xerces.internal.impl.xs.util;

import java.lang.reflect.Array;
import java.util.AbstractList;

import com.sun.org.apache.xerces.internal.xs.datatypes.ObjectList;

/**
 * Contains a list of Objects.
 *
 * @xerces.internal
 *
 * @version $Id: ObjectListImpl.java,v 1.2 2010-10-26 23:01:04 joehw Exp $
 */
public final class ObjectListImpl extends AbstractList implements ObjectList {

    /**
     * An immutable empty list.
     */
    public static final ObjectListImpl EMPTY_LIST = new ObjectListImpl(new Object[0], 0);

    // The array to hold all data
    private final Object[] fArray;

    // Number of elements in this list
    private final int fLength;

    public ObjectListImpl(Object[] array, int length) {
        fArray = array;
        fLength = length;
    }

    public int getLength() {
        return fLength;
    }

    public boolean contains(Object item) {
        if (item == null) {
            for (int i = 0; i < fLength; i++) {
                if (fArray[i] == null)
                    return true;
            }
        }
        else {
            for (int i = 0; i < fLength; i++) {
                if (item.equals(fArray[i]))
                    return true;
            }
        }
        return false;
    }

    public Object item(int index) {
        if (index < 0 || index >= fLength) {
            return null;
        }
        return fArray[index];
    }

    /*
     * List methods
     */
    public Object get(int index) {
        if (index >= 0 && index < fLength) {
            return fArray[index];
        }
        throw new IndexOutOfBoundsException("Index: " + index);
    }

    public int size() {
        return getLength();
    }

    public Object[] toArray() {
        Object[] a = new Object[fLength];
        toArray0(a);
        return a;
    }

    public Object[] toArray(Object[] a) {
        if (a.length < fLength) {
            Class arrayClass = a.getClass();
            Class componentType = arrayClass.getComponentType();
            a = (Object[]) Array.newInstance(componentType, fLength);
        }
        toArray0(a);
        if (a.length > fLength) {
            a[fLength] = null;
        }
        return a;
    }

    private void toArray0(Object[] a) {
        if (fLength > 0) {
            System.arraycopy(fArray, 0, a, 0, fLength);
        }
    }
}

⏎ com/sun/org/apache/xerces/internal/impl/xs/util/ObjectListImpl.java

Or download all of them as a single archive file:

File name: jre-rt-com-1.8.0_191-src.zip
File size: 8099783 bytes
Release date: 2018-10-28
Download 

⇒ Backup JDK 8 Installation Directory

⇐ JRE 8 rt.jar - org.* Package Source Code

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)