[java-completion] Complete statement: complete to method instead of field

Fixes IDEA-23781 Complete statement: missing method body

GitOrigin-RevId: 8d37de51bc4e90f36fbf2bbb30e0e50edc79f763

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

@@ -15,6 +15,7 @@
  */
 package com.intellij.codeInsight.editorActions.smartEnter;
 
+import com.intellij.codeInsight.daemon.JavaErrorBundle;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.*;
@@ -28,6 +29,31 @@ import static com.intellij.psi.PsiModifier.*;
 public class MissingMethodBodyFixer implements Fixer {
   @Override
   public void apply(Editor editor, JavaSmartEnterProcessor processor, PsiElement psiElement) throws IncorrectOperationException {
+    if (psiElement instanceof PsiField) {
+      // replace something like `int x` with `int x() {...}`
+      // while it's ambiguous whether user wants a field or a method, declaring a field is easier (just append a semicolon),
+      // so completing a method looks more useful
+      PsiField field = (PsiField)psiElement;
+      if (field.hasInitializer()) return;
+      PsiElement lastChild = field.getLastChild();
+      if (!(lastChild instanceof PsiErrorElement)) return;
+      if (!((PsiErrorElement)lastChild).getErrorDescription().equals(JavaErrorBundle.message("expected.semicolon"))) return;
+      PsiModifierList modifiers = field.getModifierList();
+      if (modifiers == null) return;
+      // Impossible modifiers for a method
+      if (modifiers.hasExplicitModifier(TRANSIENT) || modifiers.hasExplicitModifier(VOLATILE)) return;
+      // Modifier combination which is unlikely to see on methods but quite reasonable on fields
+      if ((modifiers.hasExplicitModifier(STATIC) || modifiers.hasExplicitModifier(PRIVATE)) &&
+          modifiers.hasExplicitModifier(FINAL)) {
+        return;
+      }
+      int endOffset = field.getTextRange().getEndOffset();
+      editor.getDocument().insertString(endOffset, "(){}");
+      editor.getCaretModel().moveToOffset(endOffset + 1);
+      processor.registerUnresolvedError(endOffset + 1);
+      processor.setSkipEnter(true);
+      return;
+    }
     if (!(psiElement instanceof PsiMethod)) return;
     PsiMethod method = (PsiMethod) psiElement;
     if (!shouldHaveBody(method)) return;

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

@@ -1,6 +1,7 @@
 public class Test {
 
-    private String s;<caret>
+    private String s(<caret>) {
+    }
 
     @Deprecated private String foo;
 }

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

@@ -0,0 +1,3 @@
+public class FieldWithEquals {
+  int test=<caret>
+}

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

@@ -0,0 +1,3 @@
+public class FieldWithEquals {
+    int test = <caret>;
+}

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

@@ -1,3 +1,4 @@
 public class Test {
-    String s;<caret>
+    String s(<caret>) {
+    }
 }

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

@@ -0,0 +1,3 @@
+public class FieldWithEquals {
+  static final int foo<caret>
+}

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

@@ -0,0 +1,3 @@
+public class FieldWithEquals {
+    static final int foo;<caret>
+}

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

@@ -84,6 +84,8 @@ public class CompleteStatementTest extends EditorActionTestCase {
   public void testIncompleteElseIf() { doTest(); }
   public void testField() { doTest(); }
   public void testMethod() { doTest(); }
+  public void testLikelyField() { doTest(); }
+  public void testFieldWithEquals() { doTest(); }
   public void testClass() { doTest(); }
   public void testInnerEnumBeforeMethod() { doTest(); }
   public void testInnerEnumBeforeMethodWithSpace() { doTest(); }