Java class loader

What is Java ClassLoader?

We know that Java Program runs on Java Virtual Machine (JVM). When we compile a Java Class, it transforms it in the form of bytecode that is platform and machine independent compiled program and store it as a .class file. After that when we try to use a Class, Java ClassLoader loads that class into memory.

There are three types of built-in ClassLoader in Java:

1.Bootstrap Class Loader – It loads JDK internal classes, typically loads rt.jar and other core classes for example java.lang.* package classes

2.Extensions Class Loader – It loads classes from the JDK extensions directory, usually $JAVA_HOME/lib/ext directory.

3.System Class Loader – It loads classes from the current classpath that can be set while invoking a program using -cp or -classpath command line options.

1-->You should never be messing with rt.jar, it contains class files which is trusted by JVM and loaded without stringent security check it does for other class files. The runtime (rt.jar) holds all the (most of the..) java classes that form the Java SE. It is added to the classpath automatically

follow linkhttps://www.journaldev.com/349/java-classloader