Scanner

Scanner Methods

next()          returns the next element in the Scanner object as a String 
                (reads up to white space) (i.e. space, tab, or new line character) 
nextLine()      returns the next line in the Scanner object as a String (discards the new line character)

nextByte()      returns the next element in the Scanner object as a byte
nextShort()     returns the next element in the Scanner object as a short
nextInt()       returns the next element in the Scanner object as an int
nextLong()      returns the next element in the Scanner object as a long
nextFloat()     returns the next element in the Scanner object as a float
nextDouble()    returns the next element in the Scanner object as a double

hasNext()       returns true if there is another element in the Scanner object
hasNextLine()   returns true if there is another line in the Scanner object

hasNextByte()   returns true if the next element in the Scanner object is a byte
hasNextShort()  returns true if the next element in the Scanner object is a short
hasNextInt()    returns true if the next element in the Scanner object is an int
hasNextLong()   returns true if the next element in the Scanner object is a long
hasNextFloat()  returns true if the next element in the Scanner object is a float
hasNextDouble() returns true if the next element in the Scanner object is a double




Examples:




import java.util.*;


class Main {
  public static void main(String[] args) {

    // Creates a Scanner object.
    // You can get input from the user.
    // The variable kb will refer to the object.
    // The variable can be called kb,
    // or keyboard, or scan, or ?
    // Variables should always start with a
    // lower case letter, and then you can use
    // more letters or digits or an _

    Scanner kb = new Scanner(System.in);
    
    System.out.println("Area of a Triangle");
    System.out.println();
    System.out.println();

    // We prompt the user to enter the width
    // NOTE: we use print, NOT println()
    System.out.print("Enter the width: ");
    
    // The user should enter the width
    // We will convert the input to an int
    int width = kb.nextInt();
    kb.nextLine(); // flush the buffer

    // We prompt the user to enter the height.
    // NOTE: we use print, NOT println()
    System.out.print("Enter the height: ");

    // The user should enter the height.
    // We will convert the input to an int
    int height = kb.nextInt();
    kb.nextLine(); // flush the buffer

    // Here we calculate the area and store
    // the answer in the variable area.
    int area = width * height;

    // Skip a line before printing output
    System.out.println(); 

    // Finally, we print out the result.
    System.out.println("The area is " + area + " Square Units.");

  }
}




Scanner scan = new Scanner(System.in);  // reads from the keyboard

System.out.print("Enter your grade ");
int grade = scan.nextInt();  // stops and waits for the user to enter an integer number and press enter
System.out.println(grade);   // prints out the number that the user entered



Scanner scan = new Scanner("12 5 7");
       
scan.nextInt() // returns 12 as an int (and removes the 12 from the list) 
out.println(scan.nextInt()); // prints out 5 (and removes the 5 from the list) 
out.println(scan.nextInt()); // prints out 7 (and removes the 7 from the list) 



Scanner scan = new Scanner("abc 5 xyz");
       
out.println(scan.next()); // prints out abc 
out.println(scan.nextInt()); // prints out 5 
out.println(scan.next()); // prints out xyz



Scanner scan = new Scanner("12 xyz 7");
       
out.println(scan.nextInt()); // prints out 12
if (scan.hasNextInt()) 
	out.println(scan.nextInt()); // this is skipped
else
	out.println(scan.next()); // prints out xyz       		 
out.println(scan.nextInt()); // prints out 7




Scanner scan = new Scanner("12 5 7");
		
int sum = 0;
while (scan.hasNextInt())
{
	int value = scan.nextInt();
	sum = sum + value;
	System.out.print(value+" "); // prints out 12 5 7
}
System.out.println("The sum is " + sum);  // prints out 24




// reads in the data from the file  MyFile.txt
// suppose 12 5 7 is in the file
// you must include  import java.io.*; at the top of your program
// and you must include a try block or use a throws statement

try
{
    Scanner scan = new Scanner(new File("MyFile.txt")); 
		
    int sum = 0;
    while (scan.hasNextInt())
    {
	    int value = scan.nextInt();
	    sum = sum + value;
	    System.out.print(value+" "); // prints out 12 5 7
    }
    System.out.println("The sum is " + sum);  // prints out 24
}
catch (Exception e)
{
    System.out.println("There was an error reading the file");
}