Data Types & Variables
With only two possible values, it’s the simplest Java data type.
What is a boolean?
These special methods are invoked automatically when you create an instance of a class.
What are constructors?
The statement that chooses between two blocks of code based on a boolean condition.
What is if-else?
A loop that will always execute its body at least once before checking the condition at the end.
What is do-while?
The keyword used to create an instance of a class.
What is new?
This 16-bit type is primarily used to store Unicode characters.
What is char?
The keyword used within an instance method or constructor to refer to the current object.
What is this? (implicit parameter)
The statement allowing you to pick among multiple paths based on an integer or enum?
What is a switch?
A common Java class used for parsing input from files or from the console.
What is Scanner?
The public method that serves as the entry point of a standalone Java application.
What is the main method?
This type of variable is declared inside a method or block and cannot be accessed from outside that method or block.
What is a local variable?
These methods are used and named to safely retrieve and modify a specific private variable (field) in a class.
What are getters and setters?
The logical operator that is true only if both operands are true.
What is the && (AND)?
A class used to write data to a file?
What is PrintWriter?
When using a Scanner object, this method let's you know if there is more data to read from the Scanner's input buffer.
What is hasNext()?
The region of memory where local variables are stored and method calls are tracked.
What is the stack?
An instance variable declared with this keyword is shared by every instance of the class.
What is static?
A keyword you place at the end of each switch case to prevent the code from “falling through.”
What is break?
This version of a for loop allows you to iterate over arrays or collections without using an index.
What is the enhanced for loop or for-each loop?
In Java, this operator compares two object references to check if they point to the exact same instance, instead of comparing their contents.
What is == operator?
A 32-bit floating-point type used for decimal values.
What is a float?
This object-oriented principle says that data inside an object should be hidden from outside code.
What is encapsulation?
The compact operator, represented with ? and :, that functions like an inline if-else.
What is the ternary operator? (or the conditional operator)
What is the condition section (or conditional expression)?
This complex data structure is homogenous and contiguous?
What is an array?