创建一个GUI应用程序，用于转换若干种货币。提供给用户一个JTextArea以用于输入数量。同时还应提供给用户一种选择源货币名称和目的货币名称的途径。同时为自己的测试设置至少三种不同的货币名称及转换汇率。-Create a GUI application for converting a number of currencies. To provide the user with a JTextArea for the import quantity. Should also provide an alternative source to the user name and purpose of the currency means the currency name. At the same time for their test set at least three different names and convert currency exchange rate.