13af6ab5fSopenharmony_ci# Interfaces cannot extend classes 23af6ab5fSopenharmony_ci 33af6ab5fSopenharmony_ciRule ``arkts-extends-only-class`` 43af6ab5fSopenharmony_ci 53af6ab5fSopenharmony_ci**Severity: error** 63af6ab5fSopenharmony_ci 73af6ab5fSopenharmony_ciArkTS does not support interfaces that extend classes. Interfaces can extend 83af6ab5fSopenharmony_cionly interfaces. 93af6ab5fSopenharmony_ci 103af6ab5fSopenharmony_ci 113af6ab5fSopenharmony_ci## TypeScript 123af6ab5fSopenharmony_ci 133af6ab5fSopenharmony_ci 143af6ab5fSopenharmony_ci``` 153af6ab5fSopenharmony_ci 163af6ab5fSopenharmony_ci class Control { 173af6ab5fSopenharmony_ci state: number = 0 183af6ab5fSopenharmony_ci } 193af6ab5fSopenharmony_ci 203af6ab5fSopenharmony_ci interface SelectableControl extends Control { 213af6ab5fSopenharmony_ci select(): void 223af6ab5fSopenharmony_ci } 233af6ab5fSopenharmony_ci 243af6ab5fSopenharmony_ci``` 253af6ab5fSopenharmony_ci 263af6ab5fSopenharmony_ci## ArkTS 273af6ab5fSopenharmony_ci 283af6ab5fSopenharmony_ci 293af6ab5fSopenharmony_ci``` 303af6ab5fSopenharmony_ci 313af6ab5fSopenharmony_ci interface Control { 323af6ab5fSopenharmony_ci state: number 333af6ab5fSopenharmony_ci } 343af6ab5fSopenharmony_ci 353af6ab5fSopenharmony_ci interface SelectableControl extends Control { 363af6ab5fSopenharmony_ci select(): void 373af6ab5fSopenharmony_ci } 383af6ab5fSopenharmony_ci 393af6ab5fSopenharmony_ci``` 403af6ab5fSopenharmony_ci 413af6ab5fSopenharmony_ci 42