设置一个JLabel组件、JText和JCombox组件，下拉列表框的内容初始为红色、绿色、蓝色，当在JText中输入内容回车时把输入的内容添加到下拉列表框中，当选择下拉列表框中的选项时，在JLabel中显示所选择的内容。-Set a JLabel component, JText and JCombox components, the initial drop-down list box the contents of the red, green, blue, JText the input when the input when the contents of carriage return added to the drop-down list box, when Select the drop-down list box option, in the JLabel to display the selected content.