Added new FinalFieldCouldBeStatic rule

git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@1874 51baf565-9d33-0410-a72c-fc3788e3496d

pmd/etc/changelog.txt

@@ -1,5 +1,5 @@
 ????? - 1.06:
-Added new rule: FinalizeShouldBeProtected
+Added new rules: FinalizeShouldBeProtected, FinalFieldCouldBeStatic
 Removed "verbose" attribute from PMD and CPD Ant tasks; now they use built in logging so you can do a "ant -verbose cpd" or "ant -verbose pmd".  Thanks to Philippe T'Seyen for the code.
 Added "excludes" feature to rulesets; thanks to Gael Marziou for the suggestion.
 TODO - fix it so tests and rules don't duplicate the xpath expressions

pmd/regress/test/net/sourceforge/pmd/rules/FinalFieldCouldBeStaticRuleTest.java

@@ -0,0 +1,51 @@
+package test.net.sourceforge.pmd.rules;
+
+import net.sourceforge.pmd.Rule;
+import net.sourceforge.pmd.cpd.CPD;
+import net.sourceforge.pmd.rules.XPathRule;
+
+public class FinalFieldCouldBeStaticRuleTest extends SimpleAggregatorTst {
+
+    private Rule rule;
+
+    public void setUp() {
+        rule = new XPathRule();
+        rule.addProperty("xpath", "//FieldDeclaration[@Final='true' and @Static='false']/VariableDeclarator/VariableInitializer/Expression/ConditionalAndExpression/InstanceOfExpression/PrimaryExpression/PrimaryPrefix/Literal");
+    }
+
+    public void testAll() {
+       runTests(new TestDescriptor[] {
+           new TestDescriptor(TEST1, "simple failure case", 1, rule),
+           new TestDescriptor(TEST2, "already static, OK", 0, rule),
+           new TestDescriptor(TEST3, "non-final, OK", 0, rule),
+           new TestDescriptor(TEST4, "non-primitive failure case - only works for String", 1, rule),
+           new TestDescriptor(TEST5, "final field that's a thread, OK", 0, rule)
+       });
+    }
+
+    private static final String TEST1 =
+    "public class Foo {" + CPD.EOL +
+    " public final int BAR = 42;" + CPD.EOL +
+    "}";
+
+    private static final String TEST2 =
+    "public class Foo {" + CPD.EOL +
+    " public static final int BAR = 42;" + CPD.EOL +
+    "}";
+
+    private static final String TEST3 =
+    "public class Foo {" + CPD.EOL +
+    " public int BAR = 42;" + CPD.EOL +
+    "}";
+
+    private static final String TEST4 =
+    "public class Foo {" + CPD.EOL +
+    " public final String BAR = \"42\";" + CPD.EOL +
+    "}";
+
+    private static final String TEST5 =
+    "public class Foo {" + CPD.EOL +
+    " public final Thread BAR = new Thread();" + CPD.EOL +
+    "}";
+
+}

pmd/rulesets/newrules.xml

@@ -73,6 +73,36 @@ public class Foo {
       </example>
     </rule>
 
+    <rule name="FinalFieldCouldBeStatic"
+          message="This final field could be made static"
+          class="net.sourceforge.pmd.rules.XpathRule">
+      <description>
+      If a final field is assigned to a compile-time constant, it could be
+          made static, thus saving overhead in each object
+      </description>
+        <properties>
+            <property name="xpath">
+                <value>
+                    <![CDATA[
+//FieldDeclaration
+ [@Final='true' and @Static='false']
+ /VariableDeclarator/VariableInitializer
+  /Expression/ConditionalAndExpression/InstanceOfExpression
+   /PrimaryExpression/PrimaryPrefix/Literal
+                    ]]>
+                </value>
+            </property>
+        </properties>
+        <priority>3</priority>
+
+      <example>
+  <![CDATA[
+public class Foo {
+ public final int BAR = 42; // this could be static and save some space
+}
+  ]]>
+      </example>
+    </rule>
 
   </ruleset>