Program Specification:

Write a Java program that does the following:

Prompts the user to input exactly four characters, which constitude a valid double literal in Java.

Gets whatever the user enters and stores it into a String variable, using the the Scanner's $.$nextLine$()$ method.

Determines if the input string is indeed a valid four character double literal :

Consists of exactly the following characters: $\text{'}+\text{'},\text{'}-\text{'},\text{'},($decimal point$),$ and $\text{'}0\text{'}$ through $\text{'}9\text{'}$

Either the $\text{'}+\text{'}$ or $\text{'}-\text{'}$ character may appear only as the first character

The $\text{'}?($decimal point$)$ character must appear exactly once

All other characters must be the $\text{'}0\text{'}$ through $\text{'}9\text{'}$ characters

Displays this determination to the user in a reasonable report format.

Grading:

$\backslash$table$[[$Performance Indicator,$1,2,3$