[EC82][Java] Variable can be made constant

green-code-initiative · May 30, 2024 · b9d9228 · b9d9228
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -13,6 +13,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Deleted
 
+## [1.5.5]
+
+### Added
+- [#TODO](https://github.com/green-code-initiative/ecoCode/pull/TODO) [EC82] [Java] Variable can be made constant
+
+### Changed
+
+### Deleted
+
 ## [1.5.4] - 2024-05-24
 
 ### Added

diff --git a/RULES.md b/RULES.md
@@ -59,7 +59,7 @@ Some are applicable for different technologies.
 | EC78     | Const parameter in batch update                               | Don't set const parameter in batch update => Put its in query. Creating this parameter and destroying it consumes CPU cycles and RAM unnecessarily.                                                                                                                                                                                                                                                                          |                                                                                                                                                                         | ✅    | 🚫  | 🚫 | 🚫     | 🚫   | 🚫 | 🚫   |
 | EC79     | Free resources                                                | try-with-resources Statement needs to be implemented for any object that implements the AutoCloseable interface, it save computer resources.                                                                                                                                                                                                                                                                                 |                                                                                                                                                                         | ✅    | 🚫  | 🚫 | 🚫     | 🚫   | 🚫 | 🚫   |
 | EC81     | Specify struct layouts                                        | When possible, specify struct layouts to optimize their memory footprint                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                         | 🚫   | 🚫  | 🚫 | 🚫     | 🚫   | ✅  | 🚫   |
-| EC82     | Make variable constant                                        | A variable is never reassigned and can be made constant                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                         | 🚀   | 🚀  | 🚀 | 🚀     | 🚀   | ✅  | 🚫   |
+| EC82     | Make variable constant                                        | A variable is never reassigned and can be made constant                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                         | 🚧   | 🚀  | 🚀 | 🚀     | 🚀   | ✅  | 🚫   |
 | EC83     | Replace Enum ToString() with nameof                           | When no string format is applied, use nameof instead of ToString() for performance                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                         | 🚫   | 🚫  | 🚫 | 🚫     | 🚫   | ✅  | 🚫   |
 | EC84     | Avoid async void methods                                      | Use async Task methods instead, for performance, stability and testability                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                         | 🚫   | 🚫  | 🚫 | 🚫     | 🚫   | ✅  | 🚫   |
 | EC85     | Make type sealed                                              | Seal types that don't need inheritance for performance reasons                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                         | 🚫   | 🚫  | 🚫 | 🚫     | 🚫   | ✅  | 🚫   |

diff --git a/ecocode-rules-specifications/src/main/rules/EC82/EC82.json b/ecocode-rules-specifications/src/main/rules/EC82/EC82.json
@@ -10,5 +10,8 @@
     "eco-design",
     "ecocode"
   ],
-  "defaultSeverity": "Minor"
+  "defaultSeverity": "Minor",
+  "compatibleLanguages": [
+    "JAVA"
+  ]
 }
diff --git a/ecocode-rules-specifications/src/main/rules/EC82/java/EC82.asciidoc b/ecocode-rules-specifications/src/main/rules/EC82/java/EC82.asciidoc
@@ -0,0 +1,59 @@
+:!sectids:
+
+Variable can be made constant.
+
+## Why is this an issue ?
+
+Unlike variables, constant values are known at compile time and are injected as is in the code, requiring no runtime processing and therefore reducing the environmental footprint.
+Although good compilers will const eligible variables by themselves, it is still good practice to declare them constant, as it makes the code intent clearer.
+
+### When can it be ignored ?
+
+This rule should not be ignored.
+
+## Non-compliant examples
+
+```java
+public class MyClass {
+    private int varDefinedInClassNotReassigned = 0; // Noncompliant {{Make variable constant}}
+    private int varDefinedInClassReassigned = 0;
+
+    void changeVarDefinedInClassReassigned() {
+        varDefinedInClassReassigned = 1;
+        System.out.println("varDefinedInClassReassigned = " + varDefinedInClassReassigned);
+        System.out.println("varDefinedInClassNotReassigned = " + varDefinedInClassNotReassigned);
+    }
+
+    void simpleMethod() {
+        String varDefinedInMethodNotReassigned = "hello"; // Noncompliant
+        String varDefinedInMethodReassigned = "hello";
+        varDefinedInMethodReassigned = "bye";
+
+        System.out.println("varDefinedInMethodNotReassigned = " + varDefinedInMethodNotReassigned);
+        System.out.println("varDefinedInMethodReassigned = " + varDefinedInMethodReassigned);
+    }
+}
+```
+## Compliant examples
+
+```java
+public class MyClass {
+    private static final int VAR_DEFINED_IN_CLASS_NOT_REASSIGNED = 0; // Compliant
+    private static final int VAR_DEFINED_IN_METHOD_NOT_REASSIGNED = 0; // Compliant
+    private int varDefinedInClassReassigned = 0;
+
+    void changeVarDefinedInClassReassigned() {
+        varDefinedInClassReassigned = 1;
+        System.out.println("varDefinedInClassReassigned = " + varDefinedInClassReassigned);
+        System.out.println("varDefinedInClassNotReassigned = " + VAR_DEFINED_IN_CLASS_NOT_REASSIGNED);
+    }
+
+    void simpleMethod() {
+        String varDefinedInMethodReassigned = "hello";
+        varDefinedInMethodReassigned = "bye";
+
+        System.out.println("varDefinedInMethodNotReassigned = " + VAR_DEFINED_IN_METHOD_NOT_REASSIGNED);
+        System.out.println("varDefinedInMethodReassigned = " + varDefinedInMethodReassigned);
+    }
+}
+```