如何在java gui中创建动画矩形？

To be clear, I want to have a blue circle bouncing left to right which stops on click. This part works. But I also need to have a red rectangle bouncing up and down in the same gui which also stops on click. Each object should stop individually. However, two circles appear where one is moving and the other one is just still. Thanks in Advance! Help is appreciated.To be clear, I want to have a blue circle bounc