IDEA-178933 Complete current statement for if statement without opening bracket

java/java-impl/src/com/intellij/codeInsight/editorActions/smartEnter/IfConditionFixer.java

@@ -18,6 +18,7 @@ package com.intellij.codeInsight.editorActions.smartEnter;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.*;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.IncorrectOperationException;
 
 /**
@@ -53,5 +54,13 @@ public class IfConditionFixer implements Fixer {
         doc.insertString(condition.getTextRange().getEndOffset(), ")");
       }
     }
+    else if (psiElement instanceof PsiExpression && psiElement.getParent() instanceof PsiExpressionStatement) {
+      PsiElement prevLeaf = PsiTreeUtil.prevVisibleLeaf(psiElement);
+      if (prevLeaf != null && prevLeaf.textMatches(PsiKeyword.IF)) {
+        Document doc = editor.getDocument();
+        doc.insertString(psiElement.getTextRange().getEndOffset(), ")");
+        doc.insertString(psiElement.getTextRange().getStartOffset(), "(");
+      }
+    }
   }
 }

java/java-tests/testData/codeInsight/completeStatement/IfWithoutParentheses.java

@@ -0,0 +1,6 @@
+
+class Foo {
+    public void foo() {
+        if 1 > 2<caret>
+    }
+}

java/java-tests/testData/codeInsight/completeStatement/IfWithoutParentheses_after.java

@@ -0,0 +1,8 @@
+
+class Foo {
+    public void foo() {
+        if (1 > 2) {
+            <caret> 
+        }
+    }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/CompleteStatementTest.java

@@ -84,6 +84,7 @@ public class CompleteStatementTest extends EditorActionTestCase {
   public void testForIncrementExpressionAndBody() { doTest(); }
   public void testEmptyBeforeReturn() { doTest(); }
   public void testIf() { doTest(); }
+  public void testIfWithoutParentheses() { doTest(); }
   public void testBeforeStatement() { doTest(); }
   public void testTry1() { doTest(); }
   public void testInsideResourceVariable() { doTest(); }