Respond to the following in a minimum of 175 words and also leave a couple comme

Respond to the following in a minimum of 175 words and also leave a couple comme

Respond to the following in a minimum of 175 words and also leave a couple comments under the 175 words please do not combine the comments with the 175 words.
What is the purpose of comments and whitespaces in Java?
What are the Java statements and logic necessary to create a Java program that correctly prompts users to enter a username and password? Consider that the username is not case-sensitive, but the password is. The user needs to correctly type both username and password for the program to print out “Hello World.” Clearly explain the rationale behind the logic you used.
How do the rules set by Java decrease the likelihood of programming errors?