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/beans/VetoableChangeListener.java

/*
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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.beans;

/**
 * A VetoableChange event gets fired whenever a bean changes a "constrained"
 * property.  You can register a VetoableChangeListener with a source bean
 * so as to be notified of any constrained property updates.
 */
public interface VetoableChangeListener extends java.util.EventListener {
    /**
     * This method gets called when a constrained property is changed.
     *
     * @param     evt a <code>PropertyChangeEvent</code> object describing the
     *                event source and the property that has changed.
     * @exception PropertyVetoException if the recipient wishes the property
     *              change to be rolled back.
     */
    void vetoableChange(PropertyChangeEvent evt)
                                throws PropertyVetoException;
}

⏎ java/beans/VetoableChangeListener.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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