import java.io.*;import java.util.*;public class FindDuplicatedFile {        //fileList is the list of files in this directory    static private List
     
       fileList = new ArrayList<>();    static private void getFileList(String filePath)            throws NotDirectoryExpectation{        File file = new File(filePath);        if(!file.isDirectory()){            throw new NotDirectoryExpectation();        }        File[] fileArray = file.listFiles();        if(fileArray == null) return;        for(int i = 0; i
      
        getDuplicatedFile(String filePath)                     throws NotDirectoryExpectation{        getFileList(filePath);        List
       
         duplicateFiles = new ArrayList<>();        for(int i = 0; i< fileList.size(); i++){            File temp = fileList.get(i);            for(int j = i+1; j < fileList.size(); j++){                if(fileList.get(j).getName().equals(temp.getName())                        && fileList.get(j).length() == temp.length()) {                    duplicateFiles.add(fileList.get(j));                    duplicateFiles.add(temp);                }            }        }        return duplicateFiles;    }    public static void printDuplicates(List
        
          list){        Iterator
         
           it = list.iterator();        if(list.size() == 0){            System.out.println("no Duplicated File!");        }        while(it.hasNext()){            File temp= it.next();            System.out.println(temp.getName() + '\t' +                    temp.getAbsolutePath() + '\t' + temp.length());        }    }    public static void main(String[] args){        String filePath = args[0];        try {            printDuplicates(getDuplicatedFile(filePath));        }catch (Exception e){}    }    static private class NotDirectoryExpectation extends Exception{}}
         
        
       
      
     

这个主要就是File类的使用了