Static variables in Java - Cheat Sheet & Quick Revision

overview

Recall & Review

beginner

What is a static variable in Java?

A static variable is a variable that belongs to the class, not to any specific object. It is shared by all instances of the class.

beginner

How many copies of a static variable exist in a Java program?

Only one copy of a static variable exists, regardless of how many objects of the class are created.

beginner

How do you declare a static variable in Java?

Use the keyword static before the variable type, for example: static int count;

beginner

Can static variables be accessed without creating an object?

Yes, static variables can be accessed using the class name directly, like <code>ClassName.variableName</code>.

beginner

What happens to a static variable when you change it through one object?

Changing a static variable through one object changes it for all objects because there is only one shared copy.

What keyword is used to declare a static variable in Java?

A volatile

B final

C static

D const

How many copies of a static variable exist across all instances of a class?

A One

B One per object

C None

D Depends on the number of threads

How do you access a static variable without creating an object?

A Using the class name

B Using the object reference

C Using the super keyword

D You cannot access it without an object

If you change a static variable through one object, what happens to other objects?

A They get an error

B They keep their own copy

C They reset the value

D They see the updated value

Which of these is NOT true about static variables?

A They are shared by all instances

B Each object has its own copy

C They belong to the class

D They can be accessed without creating an object

Explain what a static variable is and how it differs from instance variables in Java.

Describe how you would use a static variable to count how many objects of a class have been created.