Java Basic -How JVM Works – JVM Architecture?

JVM(Java Virtual Machine) acts as a run-time engine to run Java applications. JVM is the one that actually calls the main method present in a java code. JVM is a part of JRE(Java Run Environment).

Java applications are called WORA (Write Once Run Everywhere). This means a programmer can develop Java code on one system and can expect it to run on any other Java enabled system without any adjustment. This is all possible because of JVM.

When we compile a .java file, a .class file(contains byte-code) with the same filename is generated by the Java compiler. This .class file goes into various steps when we run it. These steps together describe the whole JVM.

Image Source : https://en.wikipedia.org/wiki/Java_virtual_machine

	class Test{
	public static void main(String args[]){
	Student s1 = new Student();
	Class c1 = s1.getClass();
	//getting class by creating JVM
	System.out.println(c1.getName());
	//Method m[] = c1.getDeclaredMethods();
	// for (Method method : m)
	// System.out.println(method.getName());
	// Field f[] = c1.getDeclaredFields();
	// for (Field field : f)
	// System.out.println(field.getName());
	// String class is loaded by bootstrap loader, and
	// bootstrap loader is not Java object, hence null
	System.out.println(String.class.getClassLoader());
	// Test class is loaded by Application loader
	System.out.println(Test.class.getClassLoader());
	}
	static class Student{
	private String name;
	private int roll;
	public void setName(String name){
	this.name = name;
	}
	public String getName(){
	return name;
	}
	public int getRoll(){
	return roll;
	}
	public void setRoll(int r){
	this.roll = r;
	}
	}
	}

view raw JvmWorks.java hosted with ❤ by GitHub