设计一合并文本文件程序，可按以下步骤实现：l　　创建一窗口框架；l　　输入三个文本文件名（可用FileDialog对象进行文件选择）；l　　分别打开前面两个文件，将其内容合并到第三个文件上，也就是file3 = file1 + file2。l　　然后再将file3的内容显示在窗口上。-The design of a consolidated text file program, according to the following steps to achieve: l create a window frame　l three text input file name (available FileDialog object file selection)　l open the first two files to merge the contents to the third files, that is, file3 = file1+ file2. l file3 and then displayed on the window.