查看指定路径里文件的个数和文件类型并打印路径

package cn;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class File05 {
    public static Map<String, List<String>> map=new HashMap<>();
    public static void main(String[] args) {
        count(System.getProperty("user.dir"));
       // System.out.println(map);
         map.forEach((k,v) -> System.out.printf("%s= %d %n %s %n",k,v.size(),v));
    }
    public static void count(String c){
       count(new File(c));
    }
    public static void count(File f){
       if(f.isDirectory()) {
           for (File t:f.listFiles()) {
               if(t.isDirectory()){
                 count(t);
               }else{
                   String s=t.getName();
                   String v=s.lastIndexOf(".")==-1 ?"未知":s.substring(s.lastIndexOf(".")+1);
                   if(map.containsKey(v)){
                      // map.put(v,map.get(v)+1);
                       List<String> list=map.get(v);
                       list.add(t.getAbsolutePath());
                       map.put(v,list);
                   }else {
                     //  map.put(v,1);
                       List<String> list=new ArrayList<>();
                               list.add(t.getAbsolutePath());
                               map.put(v,list);
                   }

               }

           }

       }
       }
    }