Class Object

The class java.lang.Class is the entry point for reflection. An instance of this class represents the metadata of a loaded Java type.

Three Ways to Obtain a Class Instance

• Class Literal: MyClass.class. Resolved at compile-time. Safe and performant because it does not trigger dynamic loading.
• Object Instance: instance.getClass(). Dynamic lookup at runtime on a concrete object.
• String Name: Class.forName("com.pkg.MyClass"). Dynamically loads the class by name at runtime. Throws ClassNotFoundException if not found.

Code Walkthrough

This program demonstrates the three ways to get a Class object.

public class ClassObjectDemo {
    public static void main(String[] args) throws ClassNotFoundException {
        // Way 1: Class Literal
        Class c1 = String.class;
// Way 2: Object Instance
        String str = "Hello";
        Class c2 = str.getClass();
// Way 3: Class.forName()
        Class c3 = Class.forName("java.lang.String");
System.out.println("Are they equal? " + (c1 == c2 && c2 == c3)); // true (same metadata reference)
    }
}

Interview-Relevant Information