Introduction to Scanner Class in Java

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.