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/awt/event/TextListener.java

/*
 * Copyright (c) 1996, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt.event;

import java.util.EventListener;

/**
 * The listener interface for receiving text events.
 *
 * The class that is interested in processing a text event
 * implements this interface. The object created with that
 * class is then registered with a component using the
 * component's <code>addTextListener</code> method. When the
 * component's text changes, the listener object's
 * <code>textValueChanged</code> method is invoked.
 *
 * @author Georges Saab
 *
 * @see TextEvent
 *
 * @since 1.1
 */
public interface TextListener extends EventListener {

    /**
     * Invoked when the value of the text has changed.
     * The code written for this method performs the operations
     * that need to occur when text changes.
     */
    public void textValueChanged(TextEvent e);

}

⏎ java/awt/event/TextListener.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 

⇒ JRE 8 rt.jar - javax.* Package Source Code

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