Java Scanner Class: Learn What it is and How to Use

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Questions and Answers

What is used in Java 5 and above to allow the user to enter their own values for a program to act on?

Hardcoded values

PrintWriter class

BufferedReader class

Scanner class (correct)

What is the problem with the program Add2Numbers.java mentioned in the text?

It always gives a result of 43 (correct)

It doesn't add the numbers correctly

It doesn't allow data input at runtime

It doesn't declare variables

In order to make the Scanner class accessible to the compiler, what do we need to do?

Import java.Scanner.*

Use Scanner class directly without importing

Import java.utils.Scanner

Import java.util.Scanner; (correct)

What does the asterisk () mean when used in 'import java.util.;'?

It imports all classes in the util package Signup and view all the answers

Which class allows us to read keyboard input in a convenient manner in Java?

Scanner class Signup and view all the answers

What type of values can be entered using the Scanner class in Java?

User-entered values at runtime Signup and view all the answers

What is used to read input from the keyboard?

Scanner class Signup and view all the answers

Which method is used to read an integer value using the Scanner class?

nextIntValue() Signup and view all the answers

How is a sequence of characters enclosed in quotation marks defined?

String literal Signup and view all the answers

How can you declare a string object in Java?

stringObject = new String(); Signup and view all the answers

Which method is used to read a line up until it reaches a white space?

nextType() Signup and view all the answers

What object should be passed to the Scanner constructor to read input from the keyboard?

System.in Signup and view all the answers

What method is used to read in a double using the Scanner class?

nextDouble() Signup and view all the answers

What should be used to read the first character of a string input using the Scanner object?

keyboardIn.next().charAt(0) Signup and view all the answers

What method is used to print the initials entered by the user in the 'Initials' class example?

System.out.print() Signup and view all the answers

What is used to prompt the user to enter a value in the 'IntegerInput' class example?

System.out.print() Signup and view all the answers

Which method reads a line up until it reaches 'Enter' using the Scanner object?

nextLine() Signup and view all the answers

Study Notes

Input and Output in Java

In Java 5 and above, the Scanner class is used to allow users to enter their own values for a program to act on.
The problem with the Add2Numbers.java program is not specified in the text, but it likely relates to the use of the Scanner class.

Importing the Scanner Class

To make the Scanner class accessible to the compiler, you need to import the java.util package using import java.util.*;.
The asterisk (*) in import java.util.*; means "all classes in the java.util package".

Reading Input in Java

The Scanner class allows us to read keyboard input in a convenient manner in Java.
The Scanner class can be used to enter integer, double, and string values.
The System.in object should be passed to the Scanner constructor to read input from the keyboard.

Reading Specific Input

The nextInt() method is used to read an integer value using the Scanner class.
The nextDouble() method is used to read a double value using the Scanner class.
The next() method is used to read a line up until it reaches a white space using the Scanner class.
The nextLine() method is used to read a line up until it reaches 'Enter' using the Scanner class.
The next() method should be used to read the first character of a string input using the Scanner object.

Strings in Java

A sequence of characters enclosed in quotation marks is defined as a string.
A string object can be declared in Java using String myString = "my string";.
The System.out.print() method is used to print the initials entered by the user in the 'Initials' class example.
The System.out.print() method is used to prompt the user to enter a value in the 'IntegerInput' class example.

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Description

Learn about the Scanner class in Java which allows users to input values for the program to act upon. This quiz covers the basics of using the Scanner class and its implementation in Java 5 and above.