만약 "setOpaque"를 "false" 로 설정되어 있다면 백그라운드 색은 적용되지 않습니다. User should see the background when my JFrame is on top of it. atomic. In this guide, we will cover how to use VarHandle for manipulating opaque memory, ensuring visibility guarantees without memory reordering issues. This replaces the AWT (Advanced Windowing Toolkit) update / paint mechanism. setOpaque (java. setOpaque (true); //Opaque값을 true로 미리 설정해 주어야 배경색이 적용된다. util. For example, when you change the background of a JCheckBox to Color. When you setOpaque ( true ), Swing wipes the background to the component’s background colour before calling your paintComponent method.