Java实现打印文件路径和展示文件目录

/*
 * 输入文件或目录，若为文件打印其路径和名字，
 * 若为目录，可选文件后缀名，若不选，则打印其下所有文件，
 * 若选择后缀名，则打印其下所有匹配后缀名的文件
 * 
 * 
 * mist lee，2014-11-29*/



import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.Scanner;


public class DisplayFileState 
{
    private static boolean flag = false;
    
    public static void main(String[] args) throws IOException
    {
        //String fileName = rawInput();
        Scanner in = new Scanner(System.in);
        System.out.print("请输入文件或者目录路径：");
        String fileName = in.nextLine();
        File f = new File(fileName);
        if(f.isFile())
        {            
            System.out.println("所输入的路径是文件");
            System.out.println(f.getCanonicalPath());
        }
        else if(f.isDirectory())
        {
            System.out.println("所输入的路径是目录");
            System.out.println("请输入要查找文件的后缀名，若为空则显示所有文件");    
            String ext = in.nextLine();
            System.out.println("您要查找的文件的后缀名是：" + ext);
            spreadFileDir(f,ext);
        }
        else
        {
            System.out.println("输入有误，请确认后重新输入！");
        }
        if(flag)
            System.out.println("没能找到你所需要的文件");
    }

    //展开目录文件
    private static void spreadFileDir(File f, String ext) throws IOException 
    {
        String[] fileNames = f.list();
        //boolean flag = false;
        
            for(int i=0;i<fileNames.length;i++)
            {
                    File subFile = new File(f.getPath(),fileNames[i]);
                    if(subFile.isFile())
                    {
                        if(ext.equals(" "))
                            System.out.println(subFile.getCanonicalPath());                    
                        else 
                        {
                            ExtensionFilter extFilter = new ExtensionFilter(ext);
                            boolean isTrue = extFilter.accept(f, fileNames[i]);
                            if(isTrue)    
                                System.out.println(subFile.getCanonicalPath());    
                            else 
                                flag = true;
                            //flag = isTrue^false;
                        }
                    }
                    else if(subFile.isDirectory())
                    {
                        spreadFileDir(subFile,ext);
                    }
                    else
                    {
                        System.out.println("something is worong!");
                    }                
            }
    }

}


//辅助过滤类，用以处理文件的后缀名
class ExtensionFilter implements FilenameFilter
{

    public ExtensionFilter(String ext)
    {        
        extension = "." + ext;        
    }
    
    @Override
    public boolean accept(File dir, String name) {
        // TODO Auto-generated method stub
        return name.endsWith(extension);
    }
    
    private String extension;
    
}