Java Variables and Literals

August 4, 2023

What is Java Variables and Literals?

Java Variables and Literals are where variables are used to store data values, while literals are used to represent fixed values in code.

Java literal is a fixed value that appears directly in the code, and its value cannot be changed during program execution.

To understand the more about Java Variables and Literals, Read the Complete Article.

Rules for Naming Variables in Java

Here are some rules for naming variables in Java:
- Variable names must begin with a letter, an underscore (_), or a dollar sign ($).
- After the first character, variable names may contain letters, digits, underscores, or dollar signs.
- Variable names are case sensitive, meaning that myVariable and myvariable are two different variables.
- Java reserves a set of keywords that cannot be used as variable names, such as if, else, while, and class.
- Variable names should be descriptive and meaningful. A good variable name should indicate the purpose of the variable in the program.

Steps to Change values of variables in Java

Declare the variable: Start by declaring the variable using the appropriate data type.

Assign a value to the variable: After declaring the variable, assign a value to it using the assignment operator "="

Change the value of the variable: To change the value of a variable, simply assign a new value to it using the same assignment operator "="

Use the new value of the variable: Once you have changed the value of the variable, you can use it in your program as needed.

Types of variables in Java programming

Local Variable: Variables declared inside a method or block of code, which are only accessible within the scope where they are declared. Local variables must be initialized before they are used.

Instance Variables Variables declared inside a class but outside any method, constructor or block, and are instantiated when an object is created from the class. They have class-level scope and each instance of the class has its own copy of the instance variables.

Class Variables: ( Static Variable ) Variables declared as static within a class, which means that they are shared among all instances of the class. They are initialized when the class is loaded and have class-level scope.

Parameter: A parameter is a variable that is used to pass data into a method or constructor. It is a special type of variable that is declared as part of the method or constructor signature and is used to receive values from the calling code.

Introduction to java

static variable in java

If statement in Java

Switch Statement in Java

Abstraction in Java

Java Literals

A Java literal is a fixed value that is directly used in the source code of a program. Literals can be of different types, such as integers, floating-point numbers, characters, strings, booleans, or null. They are constant values that cannot be changed during program execution.

Java supports different types of literals,:

Integer literals: Fixed values that represent integer numbers, such as 0, 1, -1, etc.

Floating-point literals: =Fixed values that represent decimal numbers, such as 3.14, -2.5, etc.

Boolean literals: Fixed values that represent the logical values of true and false.

Character literals: Fixed values that represent a single character, such as 'A', 'b', etc.

String literals: Fixed values that represent a sequence of characters, such as "Hello", "World", etc.

Examples Of Literals In Java

int num = 10;                  // integer literal
double price = 5.99;           // floating-point literal
char letter = 'A';             // character literal
String name = "John";          // string literal
boolean isTrue = true;         // boolean literal
Object obj = null;             // null literal

Example 2: Various types of Java literals including integer, floating-point, character, string, and boolean literals.

Run

//JavaLiteralsExample
public class Main {
   public static void main(String[] args) {
      // Integer literals
      int decimalLiteral = 100;
      int binaryLiteral = 0b1100100;
      int octalLiteral = 0144;
      int hexadecimalLiteral = 0x64;
      
      System.out.println("Decimal literal: " + decimalLiteral);
      System.out.println("Binary literal: " + binaryLiteral);
      System.out.println("Octal literal: " + octalLiteral);
      System.out.println("Hexadecimal literal: " + hexadecimalLiteral);
      
      // Floating-point literals
      float floatLiteral = 3.14159f;
      double doubleLiteral = 3.141592653589793;
      
      System.out.println("Float literal: " + floatLiteral);
      System.out.println("Double literal: " + doubleLiteral);
      
      // Character and string literals
      char charLiteral = 'a';
      String stringLiteral = "Hello, World!";
      
      System.out.println("Character literal: " + charLiteral);
      System.out.println("String literal: " + stringLiteral);
      
      // Boolean literals
      boolean trueLiteral = true;
      boolean falseLiteral = false;
      
      System.out.println("True literal: " + trueLiteral);
      System.out.println("False literal: " + falseLiteral);
   }
}

Output

Decimal literal: 100
Binary literal: 100
Octal literal: 100
Hexadecimal literal: 100
Float literal: 3.14159
Double literal: 3.141592653589793
Character literal: a
String literal: Hello, World!
True literal: true
False literal: false

Explanation:

It declares variables for each type of literal and then prints out the values of those variables using the System.out.println() method.

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