Added violation case for InefficientEmptyStringCheckRule

String.trim().isEmpty() now triggers a violation.

Fixed checkstyle

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/strings/InefficientEmptyStringCheckRule.java

@@ -4,19 +4,21 @@
 package net.sourceforge.pmd.lang.java.rule.strings;
 
 import net.sourceforge.pmd.lang.ast.Node;
+import net.sourceforge.pmd.lang.java.ast.ASTPrimaryExpression;
 import net.sourceforge.pmd.lang.java.rule.AbstractInefficientZeroCheck;
 import net.sourceforge.pmd.lang.java.symboltable.JavaNameOccurrence;
 
 /**
  * This rule finds code which inefficiently determines empty strings. This code
- * <p/>
  *
  * <pre>
  *         if(str.trim().length()==0){....
  * </pre>
  *
- * <p/> is quite inefficient as trim() causes a new String to be created.
+ * <p>
- * Smarter code to check for an empty string would be: <p/>
+ * is quite inefficient as trim() causes a new String to be created. Smarter
+ * code to check for an empty string would be:
+ * </p>
  *
  * <pre>
  * Character.isWhitespace(str.charAt(i));
@@ -26,27 +28,39 @@ import net.sourceforge.pmd.lang.java.symboltable.JavaNameOccurrence;
  */
 public class InefficientEmptyStringCheckRule extends AbstractInefficientZeroCheck {
     
-    /**
+    @Override
-     * Determine if we're dealing with String.length method
-     * 
-     * @param occ
-     *            The name occurrence
-     * @return true if it's String.length, else false
-     */
     public boolean isTargetMethod(JavaNameOccurrence occ) {
         if (occ.getNameForWhichThisIsAQualifier() != null
                 && occ.getNameForWhichThisIsAQualifier().getImage().indexOf("trim") != -1) {
             Node pExpression = occ.getLocation().jjtGetParent().jjtGetParent();
-            if (pExpression.jjtGetNumChildren() >= 3
+            if (pExpression.jjtGetNumChildren() > 2 && "length".equals(pExpression.jjtGetChild(2).getImage())) {
-                    && "length".equals(pExpression.jjtGetChild(2).getImage())) {
                 return true;
             }
         }
         return false;
     }
     
+    @Override
     public boolean appliesToClassName(String name) {
         return "String".equals(name);
     }
     
+    @Override
+    public Object visit(ASTPrimaryExpression node, Object data) {
+        
+        if (node.jjtGetNumChildren() > 3) {
+            // Check last suffix
+            if (!"isEmpty".equals(node.jjtGetChild(node.jjtGetNumChildren() - 2).getImage())) {
+                return data;
+            }
+            
+            Node prevCall = node.jjtGetChild(node.jjtGetNumChildren() - 4);
+            String target = prevCall.jjtGetNumChildren() > 0 ? prevCall.jjtGetChild(0).getImage() : prevCall.getImage();
+            if (target != null && target.indexOf("trim") != -1) {
+                addViolation(data, node);
+            }
+        }
+        return data;
+    }
+    
 }

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/rule/strings/InefficientEmptyStringCheckTest.java

@@ -0,0 +1,21 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.java.rule.strings;
+
+import net.sourceforge.pmd.testframework.SimpleAggregatorTst;
+
+/**
+ * @author Clément Fournier (clement.fournier@insa-rennes.fr)
+ *
+ */
+public class InefficientEmptyStringCheckTest extends SimpleAggregatorTst {
+
+    private static final String RULESET = "java-strings";
+
+    @Override
+    public void setUp() {
+        addRule(RULESET, "InefficientEmptyStringCheck");
+    }
+}

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/strings/xml/InefficientEmptyStringCheck.xml

@@ -132,4 +132,52 @@ public class Foo {
 }
      ]]></code>
     </test-code>
+    <test-code>
+        <description><![CDATA[
+String.trim().isEmpty() is called, should have failed
+      ]]></description>
+        <expected-problems>1</expected-problems>
+        <code><![CDATA[
+public class Foo {
+    void bar() {
+        String foo = "foo";
+        boolean b = foo.trim().isEmpty(); 
+    }
+}
+     ]]></code>
+    </test-code>
+    
+     <test-code>
+        <description><![CDATA[
+String.trim().isEmpty() is called after a chain call, should have failed
+      ]]></description>
+        <expected-problems>2</expected-problems>
+        <code><![CDATA[
+public class Foo {
+    void bar() {
+        String foo = "foo";
+        boolean b =  Arrays.toString(foo.toCharArray()).trim().isEmpty();
+        int i = 2;
+        b =  String.valueOf(i).trim().isEmpty();
+    }
+}
+     ]]></code>
+    </test-code>
+    
+     <test-code>
+        <description><![CDATA[
+String.trim().isEmpty() is called after a chain call, should have failed twice
+      ]]></description>
+        <expected-problems>2</expected-problems>
+        <code><![CDATA[
+public class Foo {
+    void bar() {
+        String foo = "foo";
+        boolean b =  Arrays.toString(foo.toCharArray()).trim().isEmpty();
+        b =  String.valueOf(2).trim().isEmpty();
+    }
+}
+     ]]></code>
+    </test-code>
+    
 </test-data>