我在同一个java文件中有以下代码。importjavax.swing.SwingUtilities;importjava.io.File;publicclassMainClass2{publicstaticvoidmain(String[]args){SwingUtilities.invokeLater(newRunnable(){publicvoidrun(){javax.swing.JFileChooserjfc=newMyFileChooser();Filefile=jfc.getSelectedFile();}});}}classMyFileChooserextendsjav