Java 8 ClassLoader Sınıf Yükleme Sırası

Giriş

Açıklaması şöyle. Yani 3 tane sınıf var. Bunlar şöyle 

1. BootStrap ClassLoader 

Açıklaması şöyle

JVM İlk Yüklenirken Çalışır

2. Extension ClassLoader

Açıklaması şöyle

The extension class loader is a child of the bootstrap class loader, and takes care of loading the extensions of the standard core Java classes so that they're available to all applications running on the platform.

The extension class loader loads from the JDK extensions directory, usually the $JAVA_HOME/lib/ext directory, or any other directory mentioned in the java.ext.dirs system property.

3.Application ClassLoader veya System ClassLoader

Açıklaması şöyle

Kendi sınıflarımızı yükler

Açıklaması şöyle

The system or application class loader, on the other hand, takes care of loading all the application level classes into the JVM. It loads files found in the classpath environment variable, -classpath, or -cp command line option. It's also a child of the extensions class loader.

Şeklen şöyle

Örnek

Elimizde şöyle bir kod olsun

import com.sun.javafx.util.Logging;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;

public class PrintClassLoader {

  public void printClassLoaders() throws ClassNotFoundException {

    System.out.println("Classloader of this class:" 
      + PrintClassLoader.class.getClassLoader()); // Kendi kodumuz
    System.out.println("Classloader of Logging:" 
      + Logging.class.getClassLoader()); // Extension kodu
    System.out.println("Classloader of ArrayList:" 
      + ArrayList.class.getClassLoader()); // JDK kodu
  }
}

Çıktısı şöyle.

Class loader of this class:sun.misc.Launcher$AppClassLoader@18b4aac2
Class loader of Logging:sun.misc.Launcher$ExtClassLoader@3caeaf62
Class loader of ArrayList:null