@startuml skinparam style strictuml title State Pattern class PhoneController { changeStateTo(PhoneState) handlePressButton() handlePlugPower() handleUnplugPower() } abstract class PhoneState { handlePressButton() handlePlugPower() handleUnplugPower() } class ScreenOffState extends PhoneState { handlePressButton() handlePlugPower() } class ScreenOnState extends PhoneState { handlePressButton() handlePlugPower() } class ScreenChargingState extends PhoneState { handleUnplugPower() } PhoneController -> "state 1" PhoneState : " " note right of PhoneState::handlePressButton do nothing in default methods end note note right of ScreenOffState::handlePressButton if (powerLow) { displayLowPowerMessage() } else { changeStateTo(ScreenOnState) } end note @enduml Submit amiga aws-orange black-knight bluegray blueprint cerulean-outline cerulean crt-amber crt-green cyborg-outline cyborg hacker lightgray mars materia-outline materia metal mimeograph minty plain reddress-darkblue reddress-darkgreen reddress-darkorange reddress-darkred reddress-lightblue reddress-lightgreen reddress-lightorange reddress-lightred sandstone silver sketchy-outline sketchy spacelab spacelab-white superhero-outline superhero toy united vibrant       🎉 Discover the future PlantUML Web Editor! 🚀  PNG  SVG  ASCII Art