Scanner input data types

Question

I need to write a test class that will do the following:

• a. Let the user input an integer and display it.
• b. Let the user input a float value and display it.
• c. Let the user input his/her name (no white spaces) and display the name as: “Hello <name>, welcome to Scanner!”
• d. Let the user input a character and display it.
• e. Let the user input any string (with white spaces) and display it.

My questions is, how can I simply scan just a Character and display it? And in number 2, How can I input a String with white spaces and display it? (letters "d" and "e")

I've searched around, but I cannot find the simplest solution (since I'm new to Java and programming).

Here is my code so far:

package aw;

import java.io.PrintStream;
import java.util.Scanner;

public class NewClass1
{
  public static void main(String[] args)
  {
      int num;
      double num2;
      String name;
      char c;
          Scanner sc = new Scanner(System.in);
          PrintStream ps = new PrintStream(System.out);

      //for integer
      System.out.println("Enter a number: ");
      num = sc.nextInt();
      ps.printf("%d\n", num);

      //for float
      System.out.println("Enter a float value: ");
      num2 = sc.nextDouble();
      ps.printf("%.2f\n", num2);

      //for name w/o white space
      System.out.print("Enter your first name: ");
      name = sc.next();
      ps.printf("Hello %s, welcome to Scanner\n", name);


      //for character
      System.out.print("Enter a character: ");
      c = sc.findWithinHorizon(".", 0).charAt(0);
      System.out.print(“%c”, c);

      //for name w/ white space
      System.out.print("Enter your full name: ");
      name = sc.nextLine();
      System.out.print(“%s”, name);
  }
}

I hope you can help me. Thanks!

Solution

First, there's no need to wrap System.out in a PrintStream because out already supports formatting with format() or printf() methods.

Next, you need to understand that when you input a line of data you also terminate it with a new line \n. The next<Type>() methods only consume the <Type> and nothing else. So, if a next<Type>() call may match \n, you need to skip over any extra new lines \n with another nextLine() before.

Here's your code with fixes:

  int num;
  double num2;
  String name;
  char c;

  Scanner sc = new Scanner(System.in);

  //for integer
  System.out.print("Enter a number: ");
  num = sc.nextInt();
  System.out.printf("%d\n", num);

  //for float
  System.out.print("Enter a float value: ");
  num2 = sc.nextDouble();
  System.out.printf("%.2f\n", num2);

  //for name w/o white space
  System.out.print("Enter your first name: ");
  name = sc.next();
  System.out.printf("Hello %s, welcome to Scanner\n", name);

  //for character
  System.out.print("Enter a character: ");
  c = sc.findWithinHorizon(".", 0).charAt(0);
  System.out.printf("%c\n", c);

  sc.nextLine(); // skip

  //for name w/ white space
  System.out.print("Enter your full name: ");
  name = sc.nextLine();
  System.out.printf("%s", name);

Comments

[Claude Rhay]

when I run the program, sc.nextLine doesn't allow me to scan, it ends the program right away.