27.3.9: Java Examples
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Overview
The following examples demonstrate data types, arithmetic operations, and input in Java.
Data Types
// This program demonstrates variables, literal constants, and data types. public class Main { public static void main(String[] args) { int i; double d; String s; boolean b; 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:
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//
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. public class Main { public static void main(String[] args) { int a; int b; 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:
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+, -, *, /, and %
represent addition, subtraction, multiplication, division, and modulus, respectively.
Temperature
// This program converts an input Fahrenheit temperature to Celsius. import java.util.*; public class Main { private static Scanner input = new Scanner(System.in); public static void main(String[] args) { double fahrenheit; double celsius; 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:
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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