Transcript System.out.println

Input/Output in Java
Output
• To output to the command line, we use either
System.out.print () or System.out.println()
or System.out.printf()
Examples using println:
System.out.println(“One”);
System.out.println(“Two”);
System.out.println(“Buckle My Shoe”);
or
System.out.println(“One\nTwo\nBuckle My
Shoe”);
Output Continued
• Examples using print & println
System.out.print(“One “);
System.out.print(“Two “);
System.out.print(“Buckle my shoe”);
System.out.println();
Output Continued
• Examples using + (the concatenate
operator)
int x = 10, y = 20;
System.out.println (“x =“ + x + “\ny=“
+ y + “\nx + y = “ + (x + y));
What would be output if the parenthesis
around x + y were left off?
Using printf
• System.out.printf() is a method that receives
multiple arguments.
• The first argument is a string that tells how to
print the arguments that follow.
• Example: %s means print the argument as a
string
System.out.printf(“%s\n%s\n%s\n”, “One”,
“Two”, “Buckle my shoe”);
printf continued
int number1, number2, sum;
number1=10;
number1=30;
sum = number1 + number2;
System.out.printf(“The sum of %d + %d = %d”,
number1, number2, sum);
Command line Input
• The Scanner class is used for input from the
command line.
• The Scanner class is in the package java.util so
any program using the Scanner class must first
include an import statement that is used to help
the compiler locate the class.
• All import statements appear first in a java
program before the class definition or any other
statement (other than comments).
import java.util.Scanner;
public class AddTwoNumbers
{
public static void main(String[] str)
{
int x, y;
//create a Scanner object to get input
//System.in refers to standard input object
Scanner input = new Scanner(System.in);
//Prompt for and read the first integer
//using the Scanner object’s nextInt method.
//The program waits for the user to type in
//an integer and press the ENTER key
System.out.println(“Enter the first integer:”);
x = input.nextInt();
System.out.println (“Enter the next integer:”);
y = input.nextInt();
sum = x + y;
System.out.println (“Sum is %d\n”, sum);
} //end of main
} //end of class AddTwoNumbers
Displaying output using
JOptionPane
• JOptionPane is a class in the package
javax.swing that allows output to be
displayed in a dialog box.
Example:
JOptionPane.showMessageDialog(null,
“Welcome\nto\nJava”);
produces:
String name =
JOptionPane.showInputDialog(
“What is your name?”);
String message =
“Welcome, to Java Programming! “
+ name;
JOptionPane.showMessageDialog(null,
message);