为什么要创建这个类文件？

Question

In Java all classes are loaded into the JVM dynamically, upon the first use of a class.

Does it mean if i have class in a my source file and I do not make any reference to it then its Class object is not created (ie .class file is not created)?

In the sample code below iam not making a refernce to test3 class but still its class object gets created.

class test1 {
    static {
        System.out.println("static block of test1");
    }
}   
class test2{
    static {
        System.out.println("static block of test2");
    }
}
class test3 {}
class MyExample1 {
    public static void main(String ...strings ) {
    new test1();
    new test2();
    }
}

Why test3.class file gets created?

Answer 1

.class file was created at compilation time. But, it will be loaded from .class file by first usage (probably).

From where it should be loaded without .class file?)

Answer 2

You have to distinguish between the file test3.class (which is created by the compiler) and the class object test3.class of class test3 , which is created on runtime when the class is loaded by the classloader.

The class file is always created if you compile a .java source file (compilation unit) with the class in it (most often class3.java , but it can also be named anything else, if the class is not public) - or implicitely if the class is used by another compiled class.

The class object is created by the classloader when the class is first loaded - this occurs whenever it is needed, or earlier. The normal URLClassLoader loads your class from a file with the same name, but in principle the data could also be generated on the fly, loaded from a database or similar. It (the class) then is initialized by invoking the static blocks. (The initialization is a second step, not necessarily at the same time, but both are before your first use of the class.)