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 java.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ java/security/Guard.java

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.security;

/**
 * <p> This interface represents a guard, which is an object that is used
 * to protect access to another object.
 *
 * <p>This interface contains a single method, {@code checkGuard},
 * with a single {@code object} argument. {@code checkGuard} is
 * invoked (by the GuardedObject {@code getObject} method)
 * to determine whether or not to allow access to the object.
 *
 * @see GuardedObject
 *
 * @author Roland Schemers
 * @author Li Gong
 */

public interface Guard {

    /**
     * Determines whether or not to allow access to the guarded object
     * {@code object}. Returns silently if access is allowed.
     * Otherwise, throws a SecurityException.
     *
     * @param object the object being protected by the guard.
     *
     * @exception SecurityException if access is denied.
     *
     */
    void checkGuard(Object object) throws SecurityException;
}

⏎ java/security/Guard.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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