JVM Tutorials - Herong's Tutorial Examples - v5.13, by Herong Yang
ClassChecker.java - Reports Class Locations
This section provides a tutorial example, ClassChecker.java, which reports class locations from the classpath of a given class.
ClassChecker.java can also be used to find the location of a given class. For example:
herong> java ClassChecker ClassChecker Class: ClassChecker Loader: jdk.internal.loader.ClassLoaders$AppClassLoader@629f0666 Loaded from: file:/C:/herong/ClassChecker.class All locations: file:/C:/herong/ClassChecker.class
The output tells me that class "ClassChecker" is loaded from a file at: C:/herong/ClassChecker.class
If I check the "Hello" class from "MyZIP.zip", it tells me that "Hello" is loaded from a JAR file: C:/herong/MyZIP.zip:
herong> java -classpath MyZIP.zip;. ClassChecker Hello Class: Hello Loader: jdk.internal.loader.ClassLoaders$AppClassLoader@129a8472 Loaded from: jar:file:/C:/herong/MyZIP.zip!/Hello.class All locations: jar:file:/C:/herong/MyZIP.zip!/Hello.class
If a class is found at multiple locations from the classpath, it reports me all the locations:
herong> java -classpath .;.\src\Hello.jar;.\src;.\MyZIP.zip \ ClassChecker Hello Class: Hello Loader: jdk.internal.loader.ClassLoaders$AppClassLoader@129a8472 Loaded from: jar:file:/C:/herong/src/Hello.jar!/Hello.class All locations: jar:file:/C:/herong/src/Hello.jar!/Hello.class file:/C:/herong/src/Hello.class jar:file:/C:/herong/MyZIP.zip!/Hello.class
Table of Contents
JVM (Java Virtual Machine) Specification
Java HotSpot VM - JVM by Oracle/Sun
java.lang.Runtime Class - The JVM Instance
java.lang.System Class - The Operating System
►ClassLoader Class - Class Loaders
What Is java.lang.ClassLoader Class
Accessing the ClassLoader of a Class
loadClass() Method - Loading Classes Explicitly
getSystemResource() Method - Finding Files
Class Loading Problem - JAR Hell
ClassChecker.java - Reports Class Loader
►ClassChecker.java - Reports Class Locations
"superclass access check failed" Class Load Error
Class Loading Followed by Class Initialization
Class Class - Class Reflections
JVM Stack, Frame and Stack Overflow
Thread Testing Program and Result
CPU Impact of Multi-Thread Applications
I/O Impact of Multi-Thread Applications
Micro Benchmark Runner and JVM Options
Micro Benchmark Tests on "int" Operations
Micro Benchmark Tests on "long" Operations
Micro Benchmark Tests in JIT Compilation Mode
Micro Benchmark Tests on "float" and "double" Operations