Content
This does not apply to files that do not contain any class declarations, such as package-info.java. In Java, constants must be defined with the keyword final. If the constant is used by multiple methods, declare it as static final. It is a good idea to define static final variables as privateif no other class has an interest in them.
- Note that this implies that other white space characters must be written in escaped form.
- Test classes are named starting with the name of the class they are testing, and ending with Test.
- The short forms (e.g. \t) are commonly used and easier to recognize than the corresponding longer forms (\011, \u0009).
A test class has a name that ends with Test, for example, HashIntegrationTest. If it covers a single class, its name is the name of that class plus Test, for example HashImplTest. Comments are not enclosed in boxes drawn with asterisks or other characters.
Do not use wildcard imports
Location of config file for SuppressionFilter can be defined by system property org.checkstyle.sun.suppressionfilter.config (default value is checkstyle-suppressions.xml). Location of config file for SuppressionXpathFiltercan be defined by system property org.checkstyle.sun.suppressionxpathfilter.config (default value is checkstyle-xpath-suppressions.xml). This is a fragment—a noun phrase or verb phrase, not a complete sentence. It does not begin with A is a…, or This method returns…, nor does it form a complete imperative sentence like Save the record.. However, the fragment is capitalized and punctuated as if it were a complete sentence. Interface names may also be nouns or noun phrases , but may sometimes be adjectives or adjective phrases instead . After each comma that follows an enum constant, a line-break is optional.
Comments should not be trivial, i.e. should not repeat information visible in the method name and parameter names and types. We like to move fast and build working prototypes. Functionality is often omitted in the interest of carrying out a demonstration or a specific case study on a deadline. It is all too easy to forget that a particular function is only half-implemented, turning a conscious simplification into a strange bug. Beyond where required by the language or other style rules, and apart from literals, comments and Javadoc, a single ASCII space also appears in the following places only. Package and import statements (see Sections 3.2 Package statement and 3.3 Import statements). Methods of a class that share the same name appear in a single contiguous group with no other members in between.
Access Level Modifiers
It is easier to understand changes to functionality later when they are not mixed with changes to wrapping, brackets, comments etc. Like other programming style guides, the issues covered span not only aesthetic issues of formatting, but other types of conventions or coding standards as well. However, this document focuses primarily on the hard-and-fast rules that we follow universally, and avoids giving advice that isn’t clearly enforceable . Catch each exception separately as separate catch blocks after a single try. This can be awkward but is still preferable to catching all Exceptions.Beware repeating too much code in the catch blocks.
- When a reference to a static class member must be qualified, it is qualified with that class’s name, not with a reference or expression of that class’s type.
- This does not apply to files that do not contain any class declarations, such as package-info.java.
- Only space characters may be used for indentation.
- We like to move fast and build working prototypes.
- Do not reformat code in files unrelated to the current changeset, even if the code doesn’t adhere to the guidelines.
- Format an abbreviation as a word if the it is part of a longer class name.
Within method bodies, as needed to create logical groupings of statements. When a class has multiple constructors, or multiple methods with the same name, these appear sequentially, with no intervening members. Wildcard static imports are encouraged for test imports like JUnit, EasyMock, and Hamcrest.
1 License or copyright information, if present
Javadoc is addressed separately in Section 7, Javadoc. This practice is permitted, but is never required by Google Style. It is not even required to maintain horizontal alignment in places where it was already used. Lines where obeying the column limit is not possible .
- Especially if the behavior of the method is not clear from the context.
- In Java, constants must be defined with the keyword final.
- The order you choose for the members and initializers of your class can have a great effect on learnability.
- Import statements should be sorted… …primarily by non-static / static with non-static imports first.
- This coding style guide is a simplified version of one that has been used with good success both in industrial practice and for college courses.
Over the long term, the vast majority of time spent on software is maintenance and operations. Someone will eventually need to reverse-engineer what you’ve written, and that someone may well be your future self who’s completely forgotten this code. If you write the comments as you create the code, it also helps double-check your thinking to have “redundant” versions of the same logic side by side in prose and symbolic form. Underscores may appear in JUnit test method names to separate logical components of the name, with each component written in lowerCamelCase, for example transferMoney_deductsFromSource. There is no One Correct Way to name test methods. A single blank line may also appear anywhere it improves readability, for example between statements to organize the code into logical subsections. A blank line before the first member or initializer, or after the last member or initializer of the class, is neither encouraged nor discouraged.
Do not reformat code in files unrelated to the current changeset, even if the code doesn’t adhere to the guidelines. Minor cleanups in files that are already touched for other reasons are fine. Put the cleanups in a separate patch if you think it will simplify the review process. Large cleanups should always go in a separate changeset. Putting opening braces on the end of the line is a long standing Java convention. Always suffix the names of numeric variables with the units in which they are expressed.
Variables and Constants
If the block comes last in an enclosing block, it must have braces. Although method parameters should typically not be mutated, consistently marking all parameters in every methods as final is an exaggeration. Having more than one wildcard import makes the code fragile since adding a new class in one of the imported packages can introduce a name clash.
Format an abbreviation as a word if the it is part of a longer class name. For bound instance method references, or methods with arity greater than one, a lambda expression may be easier to understand and therefore preferred. Especially if the behavior of the method is not clear from the context. Agreeing on a common line delimiter character is important since different operating systems have different defaults.
This rule applies even when modifiers such as static orprivate differ between the methods. This document serves as the complete definition of Google’s coding standards for source code in the Java™ Programming Language. A Java source file is described as being in Google Style if and only if it adheres to the rules herein. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check’s default tokens.
Always use symbolic constants for numbers included in expressions unless the source and meaning of the number is completely obvious. Numeric constants in Java can have underscores in them to group thousands. This makes it easier to visually sanity check the magnitude of the constant. Any of the standard “block tags” that are used appear in the order @param,@return, @throws, @deprecated, and these four types never appear with an empty description. When a block tag doesn’t fit on a single line, continuation lines are indented four spaces from the position of the @. Even when final and immutable, local variables are not considered to be constants, and should not be styled as constants. Except as noted below, any line that would exceed this limit must be line-wrapped, as explained in Section 4.5, Line-wrapping.
Units and Symbolic Constants
All class and interface names start with uppercase and are followed by lowercase letters ; for example, BankTeller. On both sides of the double slash (//) that begins an end-of-line comment. Here, multiple spaces are allowed, but not required.
How I plan my code tasks?
That doesn’t mean that programmers using them are evil or incompetent. It does mean that the constructs are not essential and can be expressed just as well or even better with other language constructs. A style guide makes you a more productive programmer because it reduces gratuitous choice. If you don’t have to make choices about trivial matters, you can spend your energy on the solution of real problems. Test classes are named starting with the name of the class they are testing, and ending with Test. When line-wrapping, each line after the first is indented at least +8 from the original line. Command lines in a comment that may be cut-and-pasted into a shell.
