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🔍 JAVA INTERVIEW QUESTIONS

❓ Can we overload the main() method? 🔄

✅ Yes, we can have multiple methods with the name "main" in a single class. However, if we run the class, the java runtime environment will look for the main method with syntax as public static void main(String args[]). 🏃‍♂️

❓ Can we have multiple public classes in a java source file? 🤔

✅ We can't have more than one public class in a single java source file. A single source file can have multiple classes that are not public. 📄

❓ What is a Java Package and which package is imported by default? 📦

✅ Java package is the mechanism to organize the java classes by grouping them. The grouping logic can be based on functionality or modules based. A java class fully classified name contains package and class name.

For example, java.lang.Object is the fully classified name of Object class that is part of java.lang package.

The java.lang package is imported by default and we don't need to import any class from this package explicitly. 🛍️

❓ What are access modifiers in Java? 🛡️

✅ Java provides access control through public, private and protected access modifier keywords. When none of these are used, it's called default access modifier.

A java class can only have public or default access modifier. Read Java Access Modifiers to learn more about these in detail. 📘

❓ What is a final keyword? 🔒

✅ The final keyword is used with Class to make sure no other class can extend it. For example, the String class is final and we can't extend it..

We can use the final keyword with methods to make sure child classes can't override it.

Java's final keyword can be used with variables to make sure that it can be assigned only once. However the state of the variable can be changed, for example, we can assign a final variable to an object only once but the object variables can change later on.

Java interface variables are by default final and static. 🎯

❓ What is a static keyword? 🚀

✅ The static keyword can be used with class-level variables to make it global i.e all the objects will share the same variable.

We can use static keyword with methods also. A static method can access only static variables of class and invoke only static methods of the class. Read more in detail at java static keyword. 🌀

❓ What is finally and finalize in java? 🎉

✅ The finally block is used with try-catch to put the code that you want to get executed always, even if an exception is thrown by the try-catch block. finally block is mostly used to release resources created in the try block.

The finalize() is a special method in Object class that we can override in our classes. This method gets called by the garbage collector when the object is getting garbage collected. This method is usually overridden to release system resources when the object is garbage collected. 🧹

❓ Can we declare a class as static? 🏢

✅ We can't declare a top-level class as static however an inner class can be declared as static. If the inner class is declared as static, it's called a static nested class.

The static nested class is the same as any other top- level class and is nested for only packaging convenience.

Read more about inner classes at java inner class. 📦

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