#1428 False positive in UnusedPrivateField when local variable hides member variable

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/symboltable/DeclarationFinderFunction.java

@@ -0,0 +1,41 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+package net.sourceforge.pmd.lang.java.symboltable;
+
+import net.sourceforge.pmd.lang.symboltable.NameDeclaration;
+import net.sourceforge.pmd.lang.symboltable.NameOccurrence;
+import net.sourceforge.pmd.util.UnaryFunction;
+
+public class DeclarationFinderFunction implements UnaryFunction<NameDeclaration> {
+
+    private NameOccurrence occurrence;
+    private NameDeclaration decl;
+
+    public DeclarationFinderFunction(NameOccurrence occurrence) {
+        this.occurrence = occurrence;
+    }
+
+    public void applyTo(NameDeclaration nameDeclaration) {
+        if (isDeclaredBefore(nameDeclaration) && isSameName(nameDeclaration)) {
+            decl = nameDeclaration;
+        }
+    }
+
+    private boolean isDeclaredBefore(NameDeclaration nameDeclaration) {
+        if (nameDeclaration.getNode() != null && occurrence.getLocation() != null) {
+            return nameDeclaration.getNode().getBeginLine() <=
+                    occurrence.getLocation().getBeginLine();
+        }
+
+        return true;
+    }
+
+    private boolean isSameName(NameDeclaration nameDeclaration) {
+        return occurrence.getImage().equals(nameDeclaration.getName());
+    }
+
+    public NameDeclaration getDecl() {
+        return this.decl;
+    }
+}

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/symboltable/LocalScope.java

@@ -47,7 +47,7 @@ public class LocalScope extends AbstractJavaScope {
         if (occurrence.isThisOrSuper() || occurrence.isMethodOrConstructorInvocation()) {
             return null;
         }
-        ImageFinderFunction finder = new ImageFinderFunction(occurrence.getImage());
+        DeclarationFinderFunction finder = new DeclarationFinderFunction(occurrence);
         Applier.apply(finder, getVariableDeclarations().keySet().iterator());
         return finder.getDecl();
     }

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/unusedcode/xml/UnusedPrivateField.xml

@@ -459,6 +459,31 @@ public class UnusedPrivateFieldClass
             return m_bugTest.m_number == m_number;
         }
     }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>#1428 False positive in UnusedPrivateField when local variable hides member variable</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class IssueUnusedPrivateField {
+
+    private static Object helper;   // PMD warns unused
+
+    @BeforeClass
+    public static void setUpClass() {
+        helper = new Object();
+    }
+
+    @Test
+    public void testSomething() {
+        String str = helper.toString();     // used here
+        System.out.println("str = " + str);
+
+        String helper = "some new string";  // hidden here
+        System.out.println("helper = " + helper);
+    }
 }
         ]]></code>
     </test-code>

src/site/markdown/overview/changelog.md

@@ -14,6 +14,9 @@
 
 **Bugfixes:**
 
-*   [#1429](https://sourceforge.net/p/pmd/bugs/1429/): Java - Parse Error: Cast in return expression
+*   java-unusedcode/UnusedPrivateField
+    *   [#1428](https://sourceforge.net/p/pmd/bugs/1428/): False positive in UnusedPrivateField when local variable hides member variable
+*   General
+    *   [#1429](https://sourceforge.net/p/pmd/bugs/1429/): Java - Parse Error: Cast in return expression
 
 **API Changes:**