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Programming Fundamentals/Variable Examples Java
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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:
// 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:
+, -, *, /, 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:
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