如何在java中使用hashMap获取特定的重复值键(How to get a specific duplicate values keys using hashMap in java)

 我的代码有这个问题。 我创建了一个hashMap，它将文件路径作为键存储，Md5哈希作为值存储，如下所示： 
 
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Valu   :  [36305b66726e9d3d8d9bbff2ec07e63b]
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value  :  [88434b1b9794feacb373048fccd901c1]
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value  :  [3743436e13b95c2e9ff46dbd8516ea48]
Key :  [C:\Users\Mbaegbu\Documents\.avi]  Value :  [416c2fe27204ce3a78abfb18963c4eb7]
Key :  [C:\Users\Mbaegbu\Documents\.jpg]  Value :  [8fd65bee3e7d26328e978cf2925c3625]
Key :  [C:\Users\Mbaegbu\Documents\.avi]  Value :  [37ba22d609b4e384c00c35ca70a1837d]
 
 我只希望它显示重复值，它键等价如下： 
 
  Key:[C:\Users\Mbaegbu\Documents\.jpg]  Value:[f884c30bfad89a285507d4c381700583]
  Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value:[f884c30bfad89a285507d4c381700583]
  Key :  [C:\Users\Mbaegbu\Documents\.jpg]  Value:[f884c30bfad89a285507d4c381700583]
 
 这是我的代码，当我运行它时，它显示如下的空集： 
 
 null null null null 
 
  Map<Set<String>, List<String>> map = new HashMap<>();
           try {
                for(File file : f.listFiles()){
                   //System.out.println((hashed(file)));
                        map.put(file(file),(hashed(file)));

               }

           } catch (IOException ex) {
               Logger.getLogger(DelDuplicate.class.getName()).log(Level.SEVERE,    null,   ex);
           }
          Map<Set<String>,List<String>> map2 = new HashMap<>();
          map2.putAll(map);
           for (Map.Entry<Set<String>, List<String> > entry : map2.entrySet()) {
               //System.out.println(" Key :  " + entry.getKey() 
                                  //+ "  Value :  " + entry.getValue());

                modedHash mode = new modedHash();
               System.out.println(mode.getKeys(getDuplicate(entry.getValue())));

            }               

     }
          public class modedHash extends HashMap{
            public List<Object> getKeys(Object value){
             List<Object> keys = null;
              if(containsValue(value)){
               keys = new ArrayList<>();
                Set<String> keyset = keySet();
          for (Object key : keyset){
            if(get(key).equals(value)){
              keys.add(key);
       }
   }
  }
  return keys;
}

  public  List<String> hashed(File file) throws IOException{
  List<String> list = new ArrayList<>();
  String hash;
  if(file.exists() && file != (null)){
      //for(File f : file.listFiles()){
            hash = MD5.asHex(MD5.getHash(file));
         list.add(hash);

  //}

  }
 return list;
}
     public  Set<String> file (File f){
       Set<String> list = new HashSet<>();

      if(f.exists() && f != (null)){
      //for(File file : f.listFiles()){
          list.add(f.getPath());
      // }
    }
    return list;
  }

 public static <T> List  getDuplicate(Collection<T> check){

  final List<T> duplicates = new ArrayList<>();

  Set<T> uniques = new HashSet<T>(){
    public boolean add(T e){
        if(contains(e)){
            duplicates.add(e);
        }
        return super.add(e);
    }


  };

  for(T t : check)
      uniques.add(t);

  return duplicates;
 
 } 
 
 modedHash类扩展HashMap，用于比较实际值键.getDuplcate方法检查List并仅输出重复项。 请高度赞赏你在这个问题上的帮助。 

I have this problem with my code. i created a hashMap that store file path as key and Md5 hash as values like this:
 
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Valu   :  [36305b66726e9d3d8d9bbff2ec07e63b]
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value  :  [88434b1b9794feacb373048fccd901c1]
Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value  :  [3743436e13b95c2e9ff46dbd8516ea48]
Key :  [C:\Users\Mbaegbu\Documents\.avi]  Value :  [416c2fe27204ce3a78abfb18963c4eb7]
Key :  [C:\Users\Mbaegbu\Documents\.jpg]  Value :  [8fd65bee3e7d26328e978cf2925c3625]
Key :  [C:\Users\Mbaegbu\Documents\.avi]  Value :  [37ba22d609b4e384c00c35ca70a1837d]
 
I only wanted it to display the duplicate values and it keys equivalence like this: 
 
  Key:[C:\Users\Mbaegbu\Documents\.jpg]  Value:[f884c30bfad89a285507d4c381700583]
  Key :  [C:\Users\Mbaegbu\Documents\.jpg] Value:[f884c30bfad89a285507d4c381700583]
  Key :  [C:\Users\Mbaegbu\Documents\.jpg]  Value:[f884c30bfad89a285507d4c381700583]
 
Here is my code, when ever i run it, it displays an null set like this:
 
null null null null
 
  Map<Set<String>, List<String>> map = new HashMap<>();
           try {
                for(File file : f.listFiles()){
                   //System.out.println((hashed(file)));
                        map.put(file(file),(hashed(file)));

               }

           } catch (IOException ex) {
               Logger.getLogger(DelDuplicate.class.getName()).log(Level.SEVERE,    null,   ex);
           }
          Map<Set<String>,List<String>> map2 = new HashMap<>();
          map2.putAll(map);
           for (Map.Entry<Set<String>, List<String> > entry : map2.entrySet()) {
               //System.out.println(" Key :  " + entry.getKey() 
                                  //+ "  Value :  " + entry.getValue());

                modedHash mode = new modedHash();
               System.out.println(mode.getKeys(getDuplicate(entry.getValue())));

            }               

     }
          public class modedHash extends HashMap{
            public List<Object> getKeys(Object value){
             List<Object> keys = null;
              if(containsValue(value)){
               keys = new ArrayList<>();
                Set<String> keyset = keySet();
          for (Object key : keyset){
            if(get(key).equals(value)){
              keys.add(key);
       }
   }
  }
  return keys;
}

  public  List<String> hashed(File file) throws IOException{
  List<String> list = new ArrayList<>();
  String hash;
  if(file.exists() && file != (null)){
      //for(File f : file.listFiles()){
            hash = MD5.asHex(MD5.getHash(file));
         list.add(hash);

  //}

  }
 return list;
}
     public  Set<String> file (File f){
       Set<String> list = new HashSet<>();

      if(f.exists() && f != (null)){
      //for(File file : f.listFiles()){
          list.add(f.getPath());
      // }
    }
    return list;
  }

 public static <T> List  getDuplicate(Collection<T> check){

  final List<T> duplicates = new ArrayList<>();

  Set<T> uniques = new HashSet<T>(){
    public boolean add(T e){
        if(contains(e)){
            duplicates.add(e);
        }
        return super.add(e);
    }


  };

  for(T t : check)
      uniques.add(t);

  return duplicates;
 
}
 
the modedHash class extends HashMap which is used to compare the actual values keys.The getDuplcate method checks the List and output only duplicates. Please your help in this issue will be highly appreciated.

原文：https://stackoverflow.com/questions/27274612