Java Development Overview

Questions and Answers

When was the Java programming language developed and by whom? When was it introduced to the public?

The Java programming language was developed in the early 1990s by James Gosling at Sun Microsystems and was introduced to the public in 1995.

Where does processing begin in a Java application?

The processing of a Java application begins with the main method.

What do you predict would be the result of the following line in a Java program: System.out.println("Hello");?

The characters 'Hello' will be printed on the computer screen.

What do you predict would be the result of the following line in a Java program: //prints hello System.out.println("Hello");?

The entire line of code is a comment, so there is no result. Signup and view all the answers

Which of the following are not valid Java identifiers? (Select all that apply)

12345 Signup and view all the answers

Evaluate the following identifiers for a program: x, scoreSum, sumOfTheTestScoresOfTheStudents, smTstScr. Which is a good name to use?

scoreSum Signup and view all the answers

What is white space? How does it affect program execution and readability?

White space is spaces, tabs, and newline characters that separate words and symbols in a program. The compiler ignores extra white space; therefore, it doesn't affect execution. However, it is crucial to use white space appropriately to make a program readable. Signup and view all the answers

What is Java bytecode?

A low-level representation of a Java source code program, translated by the Java compiler. Signup and view all the answers

What type of error is caused by misspelling a Java reserved word?

Compile-time error Signup and view all the answers

What occurs when calculating the average of an empty list of numbers?

Run-time error Signup and view all the answers

What is described by printing a student's high test grade when the student's average test grade should have been output?

Logical error Signup and view all the answers

Study Notes

Java Development and Introduction

Developed in the early 1990s by James Gosling at Sun Microsystems.
Publicly introduced in 1995.

Java Application Processing

Processing starts with the main method in a Java application.

Standard Output in Java

Executing System.out.println("Hello"); prints "Hello" on the screen.
Comments, such as //prints hello, are ignored during execution, resulting in no output.

Valid Java Identifiers

Identifiers like RESULT, result, x1234y, and answer_7 are valid.
12345 and black&white are invalid identifiers due to starting with a digit and invalid character usage, respectively.

Identifier Naming Conventions

scoreSum is a good identifier name for representing test score sums.
Names like x, smTstScr may be less descriptive and therefore not as good.

White Space in Java

Refers to spaces, tabs, and newline characters that separate code elements.
Extra white space does not affect program execution but enhances human readability.

Java Bytecode

A low-level representation of Java source code generated by the Java compiler.
Bytecode can be executed by Java interpreters and may be transported over the web.

Types of Errors in Java

Compile-time error: Occurs from misspelling a Java reserved word.
Run-time error: Happens when performing operations like dividing zero by zero.
Logical error: Arises when incorrect output, such as printing a student's high score instead of the average, is produced.

Description

This quiz covers essential concepts in Java development, including the origins of Java, application processing, valid identifiers, and naming conventions. Test your understanding of how Java processes code and the significance of whitespace in programming.