void (PsiClass anInterface) { final PsiReferenceList extendsList = anInterface.getExtendsList(); if (extendsList == null) { return; } final PsiReferenceList implementsList = anInterface.getImplementsList(); if (implementsList == null) { return; } final PsiJavaCodeReferenceElement[] referenceElements = implementsList.getReferenceElements(); for (final PsiJavaCodeReferenceElement referenceElement : referenceElements) { extendsList.add(referenceElement); referenceElement.delete(); } }