Data Types, Variables, & Expressions

Question 1

What is a primitive data type in Java?

Answer 1

It specifies the size and type of variable values and has no additional methods.

Question 2

What are the most commonly used numeric types in Java?

Answer 2

1. int (for whole numbers)
2. double (for floating-point numbers).

Question 3

What are the integer types available in Java?

Answer 3

1. Byte
2. Short
3. Int
4. Long

Question 4

What are the floating-point types available in Java?

Answer 4

1. Float
2. Double

Question 5

How should you indicate a long value in Java?

Answer 5

You should end the value with an “L”.

Question 6

How should you indicate a float value in Java?

Answer 6

End the value with an “f”.

Question 7

How should you indicate a double value in Java?

Answer 7

End the value with a “d”.

Question 8

How can a floating-point number be expressed in scientific notation in Java?

Answer 8

Use an “e” to indicate the power of 10.

Question 9

What values can the boolean data type in Java take?

Answer 9

The boolean data type can only take the values true or false.

Question 10

What are boolean values mostly used for in Java?

Answer 10

Boolean values are mostly used for conditional testing.

Question 11

What is the purpose of the char data type in Java?

Answer 11

The char data type is used to store a single character.

Question 12

How should a character be enclosed in Java?

Answer 12

The character must be surrounded by single quotes, like ‘A’ or ‘c’.

Question 13

What is the String data type used for in Java?

Answer 13

The String data type is used to store a sequence of characters (text).

Question 14

How should String values be enclosed in Java?

Answer 14

String values must be surrounded by double quotes.

Question 15

Why is String considered a non-primitive data type in Java?

Answer 15

Because String refers to an object.

Question 16

What are non-primitive data types also known as, and why?

Answer 16

• ‘references’ because they refer to objects.

Question 17

Can you name some examples of non-primitive data types in Java?

Answer 17

Examples include String, Arrays, Classes, and Interfaces.

Question 18

How are primitive data types and non-primitive data types defined in Java?

Answer 18

Primitive types are predefined in Java, while non-primitive types are created by the programmer (except for String).

Question 19

What is a key functional difference between primitive and non-primitive data types in Java?

Answer 19

Non-primitive types can call methods to perform operations, whereas primitive types cannot.

Question 20

What is a key difference between primitive and non-primitive data types regarding their values?

Answer 20

A primitive type always has a value, while non-primitive types can be null.

Question 21

How do the naming conventions differ between primitive and non-primitive data types in Java?

Answer 21

Primitive types start with a lowercase letter, while non-primitive types start with an uppercase letter.

Question 22

What is the purpose of variables in Java?

Answer 22

Variables are containers for storing data values.

Question 23

How can you ensure a variable’s value cannot be changed in Java?

Answer 23

Use the final keyword to declare the variable as “final” or “constant,” making it unchangeable and read-only.

Question 24

What is type casting in Java?

Answer 24

It is when you assign a value of one primitive data type to another type.

Question 25

What are the two types of type casting in Java?

Answer 25

1. Widening Casting (automatically)
2. Narrowing Casting (manually)

Question 26

What is widening type casting in Java?

Answer 26

It is converting a smaller type to a larger type size.

Question 27

What is narrowing type casting in Java?

Answer 27

It is converting a larger type to a smaller size type.

Question 28

How can you combine text and a variable in Java?

Answer 28

Use the + character to concatenate text and a variable.

Question 29

What are identifiers in Java?

Answer 29

Identifiers are unique names used to identify Java variables.

Question 30

What is recommended when choosing identifiers for Java variables?

Answer 30

It is recommended to use descriptive names to create understandable and maintainable code.