[java] BlockJoinLinesHandler: handle more tricky cases from IDEA-263507

GitOrigin-RevId: 1661c82421ea73a3a18c349330889c309769e053

java/java-impl/src/com/intellij/codeInsight/editorActions/BlockJoinLinesHandler.java

@@ -58,7 +58,7 @@ public class BlockJoinLinesHandler implements JoinLinesHandlerDelegate {
     }
     if (foundStatement == null) return -1;
     PsiElement parent = codeBlock.getParent();
-    if (foundStatement instanceof PsiIfStatement && parent instanceof PsiBlockStatement) {
+    if (isPotentialShortIf(foundStatement) && parent instanceof PsiBlockStatement) {
       PsiElement grandParent = parent.getParent();
       if (grandParent instanceof PsiIfStatement &&
           ((PsiIfStatement)grandParent).getThenBranch() == parent &&
@@ -81,6 +81,20 @@ public class BlockJoinLinesHandler implements JoinLinesHandlerDelegate {
     return -1;
   }
 
+  private static boolean isPotentialShortIf(PsiElement statement) {
+    while (true) {
+      // JLS 14.5
+      if (statement instanceof PsiLabeledStatement) {
+        statement = ((PsiLabeledStatement)statement).getStatement();
+      }
+      else if (statement instanceof PsiForStatement || statement instanceof PsiForeachStatement || statement instanceof PsiWhileStatement) {
+        statement = ((PsiLoopStatement)statement).getBody();
+      }
+      else break;
+    }
+    return statement instanceof PsiIfStatement;
+  }
+
   private static int getForceBraceSetting(PsiElement statement) {
     CodeStyleSettings settings = CodeStyle.getSettings(statement.getContainingFile());
     final CommonCodeStyleSettings codeStyleSettings = settings.getCommonSettings(JavaLanguage.INSTANCE);

java/java-tests/testData/codeInsight/joinLines/UnwrapCodeBlockIfElse2.java

@@ -0,0 +1,12 @@
+class C {
+  private static void fn(boolean condA, boolean condB) {
+    if (condA) {<caret>
+      for(int i=0; i<10; i++)
+        if (condB) {
+          System.out.println("condA && condB");
+        }
+    } else {
+      System.out.println("!condA");
+    }
+  }
+}

java/java-tests/testData/codeInsight/joinLines/UnwrapCodeBlockIfElse2_after.java

@@ -0,0 +1,11 @@
+class C {
+  private static void fn(boolean condA, boolean condB) {
+    if (condA) { for(int i=0; i<10; i++)
+        if (condB) {
+          System.out.println("condA && condB");
+        }
+    } else {
+      System.out.println("!condA");
+    }
+  }
+}

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

@@ -197,6 +197,7 @@ public class JoinLinesTest extends LightJavaCodeInsightTestCase {
   }
   
   public void testUnwrapCodeBlockIfElse() { doTest(); }
+  public void testUnwrapCodeBlockIfElse2() { doTest(); }
   public void testAssignmentExpression() { doTest(); }
   public void testAssignmentExpression2() { doTest(); }
   public void testAssignmentExpressionPrecedence() { doTest(); }