Static blocks in Java - Cheat Sheet & Quick Revision

overview

Recall & Review

beginner

What is a static block in Java?

A static block is a block of code inside a class that runs once when the class is loaded. It is used to initialize static variables or perform setup tasks.

beginner

When does a static block execute in Java?

A static block executes only once when the class is first loaded into memory, before any objects are created or static methods are called.

intermediate

Can a class have multiple static blocks? If yes, in what order do they execute?

Yes, a class can have multiple static blocks. They execute in the order they appear in the source code, from top to bottom.

advanced

What happens if an exception occurs inside a static block?

If an exception occurs inside a static block and is not caught, it causes an ExceptionInInitializerError, preventing the class from loading properly.

intermediate

Why use static blocks instead of initializing static variables directly?

Static blocks allow complex initialization code that can't be done in a single statement, such as loops, conditionals, or try-catch for error handling.

When is a static block executed in Java?

A Every time an object is created

B When the class is loaded

C When a method is called

D When the program ends

Can a Java class have more than one static block?

A No, only one static block is allowed

B Yes, but they execute randomly

C No, static blocks are not allowed in Java

D Yes, and they execute in the order they appear

What happens if an exception is thrown inside a static block and not caught?

A The program ignores it

B The exception is converted to a runtime exception

C The class fails to load with ExceptionInInitializerError

D The exception is logged but the program continues

Which of these is a good reason to use a static block?

A To initialize static variables with complex logic

B To initialize instance variables

C To execute code every time an object is created

D To replace constructors

Static blocks run before which of the following?

A All of the above

B Before main method runs

C Before any object is created

D Before any static method or variable is accessed

Explain what a static block is and when it runs in Java.

Describe how multiple static blocks behave in a Java class.