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All rules, listed in this document, supplement or override the rules of the Google Java Style Guide.
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This rule overrides section 4.2 of Google Java Style Guide (only indentation size).
Each time a new block or block-like construct is opened, the indent increases by 4 spaces.
This rule overrides section 4.4 of Google Java Style Guide (only limit size).
Java code has a column limit of 140 characters.
This rule overrides section 4.6.3 of Google Java Style Guide.
Alignment can aid readability, but it creates problems for future maintenance. So horizontal alignment is disallowed.
All natural language sentences must follow generally accepted punctuation rules. It also means that every sentence must end with dot (.
), exclamation point (!
) or question mark (?
) depending on sentence semantics. This requirement applies to:
Exclusions:
These rules supplement section 4.8.5 of Google Java Style Guide.
Ignite 3 uses JetBrains nullability annotations. For the sake of code clarity, it is prohibited to use @NotNull
annotation, even if it compromises the completeness of the static analysis. However, it is required to use @Nullable
in the following places:
null
;null
as this parameter will not end in throwing an exception;null
.There are multiple ways to annotate a Java array, which lead to different interpretations by the static analysis tool:
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@Nullable Object[] x; // x array can *contain* null values
Object @Nullable [] x; // x itself can be null
@Nullable Object @Nullable [] x; // x array can contain null values *and* be null itself |
It is recommended to enable all inspections, related to this topic. Please note, that all nested options should also be enabled:
All these options will be set automatically when importing inspections settings from the repository.
var
keywordThe local variable type inference is the powerful feature of Java language. Nevertheless, one of the main goals of the code style guide is to ensure readability for developers, not for the compiler.
Based on this statement there are limited uses cases where var
keyword is allowed. The var
keyword is allowed only in cases where a right part of an assignment expression contains an explicit type of variable, that is for assignments of literals and the result of constructor invocation.
Allowed only for assignments of literals, result of constructor invocation and explicit casts:
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var i = 42;
var l = 42L;
var s = "Hello";
var list = new ArrayList<Integer>();
var t = (long) l; |
Disallowed for all other cases:
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var i = Integer.parseInt("42");
var s = "Hello".substring(0, 3);
var list = Arrays.asList(1, 2, 3);
var map = getMapping(); // some method invocation
var val = map.get(42); |
async
suffixAsync method is a method that returns Future
, CompletableFuture
, or CompletionStage
.
In some cases, both sync and async variants exist, and async
suffix is used to distinguish between them:
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void upsert(@Nullable Transaction tx, R rec);
CompletableFuture<Void> upsertAsync(@Nullable Transaction tx, R rec); |
In other cases, only async variant may be present, but it should have the async
suffix anyway.
CompletableFuture
- not CompletionStage
Historically Apache Ignite developers try to avoid redundant Java object instantiations due to the additional GC pressure. Of course, escape analysis exists but we can't trust this feature and should keep objects instantiation under control where it is possible and justified.
So it is recommended to avoid usage of Stream API at least on the hot code path.
Using of 3rd party libraries in production code is prohibited. But there are some exceptions to this rule: