Programming Fundamentals/Variable Examples Java

Overview

The following examples demonstrate data types, arithmetic operations, and input in Java.

Data Types

// This program demonstrates variables, literal constants, and data types.publicclassMain{publicstaticvoidmain(String[]args){inti;doubled;Strings;booleanb;i=1234567890;d=1.23456789012345;s="string";b=true;System.out.println("Integer i = "+i);System.out.println("Double d = "+d);System.out.println("String s = "+s);System.out.println("Boolean b = "+b);}}

Output

Integer i = 1234567890 Double d = 1.23456789012345 String s = string Boolean b = true 

Discussion

Each code element represents:

• // begins a comment
• public class DataTypes begins the Data Types program
• { begins a block of code
• public static void main(String[] args) begins the main function
• int i defines an integer variable named i
• ; ends each line of Java code
• double d defines a double floating-point variable named d
• string s defines a string variable named s
• boolean b defines a Boolean variable named b
• i = , d = , s =, b = assign literal values to the corresponding variables
• System.out.println calls the  standard output print line function
• } ends a block of code

Arithmetic

// This program demonstrates arithmetic operations.publicclassMain{publicstaticvoidmain(String[]args){inta;intb;a=3;b=2;System.out.println("a = "+a);System.out.println("b = "+b);System.out.println("a + b = "+(a+b));System.out.println("a - b = "+(a-b));System.out.println("a * b = "+a*b);System.out.println("a / b = "+a/b);System.out.println("a % b = "+(a%b));}}

Output

a = 3 b = 2 a + b = 5 a - b = 1 a * b = 6 a / b = 1 a % b = 1 

Discussion

Each new code element represents:

• +, -, *, /, and % represent addition, subtraction, multiplication, division, and modulus, respectively.

Temperature

// This program converts an input Fahrenheit temperature to Celsius.importjava.util.*;publicclassMain{privatestaticScannerinput=newScanner(System.in);publicstaticvoidmain(String[]args){doublefahrenheit;doublecelsius;System.out.println("Enter Fahrenheit temperature:");fahrenheit=input.nextDouble();celsius=(fahrenheit-32)*5/9;System.out.println(Double.toString(fahrenheit)+"° Fahrenheit is "+celsius+"° Celsius");}}

Output

Enter Fahrenheit temperature: 100 100° Fahrenheit is 37.7777777777778° Celsius 

Discussion

Each new code element represents:

• private static Scanner input ... defines an object to read from standard input
• input.nextDouble() reads input as a double floating-point value

References

• Wikiversity: Computer Programming

Programming Fundamentals