Java Formatting Guide

Most beginner programmers have a bit of trouble with formatting their code. They aren’t consistent and when they are told to do it a particular way, they don’t like it. Experienced programmers understand that it has no effect on the actual program and it’s pure preference however it does make a statement as to how others view your code.

I put together a brief Java Formatting guide for beginners (only formatting is explained, variables, methods, structures are not) so they have a reference to use. Keep in mind that these are mere suggestions and are not universal, mandatory.

1. Single line comments should have 1space between the last slash and the first word.
2. The open and close of a multi-line comment should have no indentation while the contents should have the indentation of 1 tab.
3. import statements do not have formatting.
4. The class declaration (public class ClassName) does indentation.
5. Any occurrence of variable { or ) } should be separated by 1 space.
6. Each method in a class should have line of white space before another structure.
7. A method’s declaration should be indented by 1 tab. The last ) and the first { of the method should be separated by 1 space.
8. Things inside of the method should be indented by 1 space.
9. If a multiple statements are on a single line, there should be a space after each semi-color.
10. Declaration lists (int var1, var2, var3) should be separated by a comma followed by a space.
11. Declaration lists that also initialize values should have a space on both sides of the assignment operator and also follow the comma space rule for declaration lists.
12. A variable name should be lowercase letters if it’s only a single word.
13. For two word variables (theCat, myMoney, somethingElse) the first letter of the first word is left lowercase and the first letter of the second word is capitalized.
14. For multi-word variables, use the same format leaving the first word’s first letter lowercase but thereafter each first letter of each word should be capitalized. (This is called camelcase.)
15. When concatenating a string, there should 1 space between any occurrences of “, + or variable name. (String n = “hello” + “world”;)
16. if statements do not have an initial indentation.
17. All operators inside of a conditional statement should have 1 space on their left and their right.
18. Numbers (in other words, not variables) should always be listed first in a conditional. (10 == variableName)
19. Things inside of an if statement should indented by 1 tab.
20. If an if statement also has an else branch, the else should should start one space after the if branch’s last } and the first bracket of the else should be once space after the keyword else.
21. In a switch statement, there should be 1 space between the colon and the next statement.
22. A for, while or do loop should all have 1 their contents indented by 1 tab.
23. There is no formatting for the for, while or do loop declaration excepting noting the conditional statement rule and the ) { rule.
24. When declaring an array, the [] always go on the variable type.
25. When declaring and initializing an array, the values should be separated by a comma followed by a space..

Do you know any other structures in java that may need special formatting rules? If so, leave a comment.

Additionally, you can download the source code of a program that show cases these formatting rules.

Once again, I don’t advocate enforcing formatting because I don’t even format things myself. I use the auto-formatter in NetBeans and if not then prettyprinter. Most respected PHP formatters can format java without much problem too.