The nextInt() method of a Scanner object reads in a string of digits (characters) and converts them into an int type.

The Scanner object reads the characters one by one until it has collected those that are used for one integer. Then it converts them into a 32-bit numeric value. Usually that value is stored in an int variable.

The picture shows a program that reads in character data and then converts it into an integer which is stored in num. Next the program does arithmetic with num and stores the result in square. Finally the result is sent to println which converts the numeric result into characters and prints them out.

The nextInt() method scans through the input stream character by character, gathering characters into a group that can be converted into numeric data. It ignores spaces and end-of-lines that may preceed the group.

A space or end-of-line character that follows a string of digits ends the group. A non-digit character cannot be part of a group (not even at the end.) For example,

and

    123   

are legitimate input, but

is not.

Question 12:
Which of the following are legitimate input for nextInt() ?
 4  
 
    45  
    
 456  
 
 923X  
 
     23   876