extract method: allow to fold parameters if calls to fields are involved

java/java-analysis-impl/src/com/intellij/refactoring/extractMethod/ParametersFolder.java

@@ -270,7 +270,7 @@ public class ParametersFolder {
         final PsiElement resolved = expression.resolve();
         if (resolved instanceof PsiVariable) {
           final PsiVariable variable = (PsiVariable)resolved;
-          if (!inputVariables.contains(variable)) {
+          if (!(variable instanceof PsiField) && !inputVariables.contains(variable)) {
             localVarsUsed[0] = true;
             return;
           }

java/java-tests/testData/refactoring/extractMethod/FoldingWithFieldInvolved.java

@@ -0,0 +1,10 @@
+class Main {
+    private String [] args;
+
+    void foo(Main m, int i) {
+        <selection>if (m.args[i] != null) {
+            System.out.println(m.args[i]);
+        }</selection>
+           
+    }
+}

java/java-tests/testData/refactoring/extractMethod/FoldingWithFieldInvolved_after.java

@@ -0,0 +1,14 @@
+class Main {
+    private String [] args;
+
+    void foo(Main m, int i) {
+        newMethod(m.args[i]);
+
+    }
+
+    private void newMethod(String arg) {
+        if (arg != null) {
+            System.out.println(arg);
+        }
+    }
+}

java/java-tests/testSrc/com/intellij/refactoring/ExtractMethodTest.java

@@ -344,6 +344,9 @@ public class ExtractMethodTest extends LightCodeInsightTestCase {
     doTest();
   }
 
+  public void testFoldingWithFieldInvolved() throws Exception {
+    doTest();
+  }
 
   public void testIDEADEV11748() throws Exception {
     doTest();