Java syntax

What is the correct file extension for a Java program?

• .java
• .js
• .py
• .txt

Answer explanation

Java files are saved with a .java extension.

Which keyword is used to declare a variable?

• variable
• var
• int
• let

Answer explanation

In Java, 'int' is used for integer variables.

What does the 'public' keyword signify in Java?

• It is private
• It is global
• It is accessible to all
• It is immutable

Answer explanation

public' allows access from any class in the program.

How do you print text to the console in Java?

• console.log()
• echo()
• System.out.println()
• PrintText()

Answer explanation

System.out.println() is the correct way to print to the console in Java.

What happens if a local int variable is used without initialization?

• It is initialized to 0
• It is assigned a default value of 1
• It results in compilation error
• it is assigned a default value of null

Answer explanation

"Local variables in Java must be explicitly initialized before use, as they do not have default values. Attempting to use an uninitialized local variable results in a compilation error.

What symbol is used to end a Java statement?

• .
• ;
• :
• #

Answer explanation

Java statements end with a semicolon (;).

Which of the following are valid Java data types?

• int
• float
• string
• boolean
• array

Answer explanation

Java supports int, float, and boolean as valid data types.

What is the correct syntax for a single-line comment?

• //
• /* ... */
• <!-- ... -->
• ''

Answer explanation

Single-line comments in Java start with //.

Which of the following are Java keywords?

• class
• interface
• if
• switch
• constant

Answer explanation

class', 'interface', 'if', and 'switch' are valid Java keywords.

What is the output of System.out.println(5 + "5")?

• 10
• 55
• Error
• undefined

Answer explanation

The + operator concatenates a string and a number, resulting in "55".