A Guide to Declaring Variables and Performing Operations in Java

Declaring Variables and Assigning Initial Values

When declaring a variable in Java, you need to specify the data type of the variable and then provide the variable name. Let’s take a look at some examples:

Declaring an Integer Variable

To declare an integer variable, use the int data type:

int num;

You can assign an initial value to the declared variable later on:

num = 100;

Alternatively, you can declare and assign a value to the variable at the same time:

int num = 100;

Declaring a Character Variable

Declaring a character variable is similar to declaring an integer variable. Use single quotes (' ') to assign an initial character:

char grade = 'A';

Declaring a Decimal Variable

To store a number with a decimal point, use the double data type:

double pi = 3.14;

Declaring a String Variable

To store a series of characters, use the String data type. Insert the string within double quotes (" "):

String greeting = "Hello, World!";

Performing Operations with Variables

In Java, you can perform various operations with variables using a variety of operators designed to work appropriately with different data types. Here are some examples:

int num1 = 10;
int num2 = 20;

int sum = num1 + num2; // addition
int sub = num1 - num2; // subtraction
int mult = num1 * num2; // multiplication
int div = num1 / num2; // division

Types of Data in Java

Java provides several types of data. Here’s a brief introduction to the main data types:

• Primitive data types: These include byte, short, int, long, float, double, char, and boolean.
• Reference/Object data types: These include Arrays, Class, Interface, and Enum.

An array is a data structure that holds consecutive data of the same type. It can be a primitive type or an object type. A class is a user-defined data type that consists of fields (variables) and methods. An interface is a collection of methods with prototypes that must be implemented in a class. An enum is a collection of specific values (constants).

By understanding these data types and how to declare variables and perform operations, you’ll be well-equipped to write efficient and effective Java programs.