Java Fundamentals Live Class: Constants, Variables, Data Types, Operators, and Objects

Java Fundamentals Live Class Overview

After last week's trial, the free live sharing class has started, and this week the live session will continue.

No registration required; simply join the meeting.

Time

The class is planned for Sunday, October 24. Exact time is pending; please follow the public account tomorrow's article and group announcement for updates.

Preparation

IntelliJ IDEA software

Java environment configuration

Pre‑install dependencies (not mandatory for this session)

It is recommended to download and build the project from GitHub ( https://github.com/JunManYuanLong/FunTester ) or Gitee ( https://gitee.com/fanapi/tester ) (also not mandatory)

Format

Tencent Meeting live broadcast; post‑class Q&A in a QQ group

No recorded video; participants with sufficient computer performance may record and add the public account watermark

Due to computer performance limitations, the host cannot record while streaming. Anyone with a capable machine is invited to help record and share the video.

Participants can purchase a 1‑yuan Q&A service or a 9.9‑yuan monthly VIP (unlimited Q&A) through the FunTester WeChat store.

Alternatively, join the 1‑yuan paid QQ group, which also serves as the live‑class Q&A group.

Pre‑study Content

Constants and Variables

① Define an int constant named COUNT with value 10 .

② Define a float constant named HEIGHT with value 10.2f .

③ and ④ Print the values of COUNT and HEIGHT .

In Java, constants are also called literals. A literal is a value directly specified in the source code, such as final int COUNT = 10 , where 10 is a literal.

Only basic types, String , and null can be assigned literals. Java supports eight kinds of literal data types:

Data Types

Basic Data Types

Java's primitive types are byte , short , int , long , char , float , double , and boolean . Their ranges are:

byte : 8‑bit, -128 to 127

short : 16‑bit, -32,768 to 32,767

int : 32‑bit, -2³¹ to 2³¹‑1

long : 64‑bit, -2⁶³ to 2⁶³‑1

float : 32‑bit, approx 3.4e‑45 to 3.4e38 (suffix f or F )

double : 64‑bit, approx 4.9e‑324 to 1.8e308 (suffix d or D optional)

boolean : true or false

char : 16‑bit Unicode character, enclosed in single quotes

Reference Data Types

Reference types are built on primitives and include arrays, classes, and interfaces. They are user‑defined and do not include C/C++‑style pointers, structs, unions, or enums.

Operators

Operator

Description

Example

+

Addition

A + B equals 30

-

Subtraction

A - B equals -10

*

Multiplication

A * B equals 200

/

Division

B / A equals 2

%

Modulo (remainder)

B % A equals 0

++

Increment (adds 1)

B++ or ++B equals 21

--

Decrement (subtracts 1)

B-- or --B equals 19

Type Conversion

Basic type conversion and explicit (cast) conversion are covered.

Java Classes and Objects

An object is an instance of a class, possessing state and behavior. For example, a dog object has attributes like color, name, breed, and behaviors such as wagging its tail or barking. A class is a template describing the attributes and behaviors of a group of objects.

Class Methods and Instance Methods

No pre‑study content provided.

Class Variables and Member Variables

No pre‑study content provided.

Follow the FunTester public account for original content, community recommendations, and to avoid unauthorized third‑party reposts.

Featured FunTester Articles

Programming Thinking for Everyone

2020 Tester Self‑Improvement

Future Tool: Fiddler Everywhere

Test Engineer Work Tips

Selenium 4 IDE Is Finally Here

Automation Testing Soul Questions: What, Why, and What to Do

Automation Testing Framework

End‑to‑End Testing in Agile

Fixed QPS Load Testing Exploration

Weak‑Network Testing: Minimum Smooth Speed?

Interface Testing Live Review