pop.add(menuItem4).addActionListener(new ActionListener(){
                               
                                public void actionPerformed(ActionEvent e){
            
           JFileChooser fileopen = new JFileChooser();

int ret = fileopen.showDialog(null, "Открыть файл");

if (ret == JFileChooser.APPROVE_OPTION) {
    File file = fileopen.getSelectedFile();
        String pathFile=  file.getPath();

             if(pathFile!=null){
                 
                 ReadExcelFile readExcel=new ReadExcelFile(pathFile,grouptovarSel,[color=red]THIS[/color]);
        
}}}}

public class FrTree {

    public void method() {
        new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                FrTree.this.toString();
            }
        };
    }
}