Hashmap holding different data types as values for instance Integer String and Object

Question

I need to create a hashmap with key as integer and it should hold multiple values of different data types  For example if the key is msg id and the values are   message of type string  timestamp of type time count of type integer  version of type integer    Then how to store the values of different data type with a single key into the hashmap

User · Answer

You have some variables that are different types in Java language like that:

 message of type string
 timestamp of type time
 count of type integer
 version of type integer

If you use a HashMap like:

HashMap<String,Object> yourHash = new HashMap<String,Object>();
yourHash.put("message","message");
yourHash.put("timestamp",timestamp);
yourHash.put("count ",count);
yourHash.put("version ",version);

If you want to use the yourHash:

for(String key : yourHash.keySet()){
  String message = (String) yourHash.get(key);
  Datetime timestamp= (Datetime) yourHash.get(key);
  int timestamp= (int) yourHash.get(key);
}

User · Answer

Do simply like below      HashMap lt String Object gt  yourHash   new HashMap lt String Object gt     yourHash put yourKey  message   message    yourHash put yourKey  timestamp  timestamp   yourHash put yourKey  count   count   yourHash put yourKey  version   version     typecast the value while getting back   For ex        int count   Integer parseInt yourHash get yourKey  count       or int count   Integer valueOf yourHash get yourKey  count       or int count    Integer yourHash get yourKey  count      or  int

User · Answer

Create an object holding following properties with an appropriate name    message  timestamp count version   and use this as a value in your map   Also consider overriding the equals   and hashCode   method accordingly if you do not want object equality to be used for comparison  e g  when inserting values into your map

User · Answer

If you don t have Your own Data Class  then you can design your map as follows  Map lt Integer  Object gt  map new HashMap lt Integer  Object gt      Here don t forget to use  instanceof  operator while retrieving the values from MAP   If you have your own Data class then then you can design your map as follows  Map lt Integer  YourClassName gt  map new HashMap lt Integer  YourClassName gt       import java util Date  import java util HashMap  import java util Map  import java util Set    public class HashMapTest   public static void main String   args        Map lt Integer Demo gt  map new HashMap lt Integer  Demo gt         Demo d1  new Demo 1  hi  new Date   1 1       Demo d2  new Demo 2  this  new Date   2 1       Demo d3  new Demo 3  is  new Date   3 1       Demo d4  new Demo 4  mytest  new Date   4 1         adding values to map     map put d1 getKey    d1       map put d2 getKey    d2       map put d3 getKey    d3       map put d4 getKey    d4         retrieving values from map     Set lt Integer gt  keySet  map keySet        for int i keySet           System out println map get i                searching key on map     System out println map containsKey d1 getKey            searching value on map     System out println map containsValue d1         class Demo      private int key      private String message      private Date time      private int count      private int version       public Demo int key String message  Date time  int count  int version           this key key          this message   message          this time   time          this count   count          this version   version            public String getMessage             return message            public Date getTime             return time            public int getCount             return count            public int getVersion             return version            public int getKey             return key             Override     public String toString             return  Demo  message     message      time     time                      count     count      version     version

User · Answer

Define a class to store your data first  public class YourDataClass        private String messageType      private Timestamp timestamp      private int count      private int version          your get setters                     And then initialize your map   Map lt Integer  YourDataClass gt  map   new HashMap lt Integer  YourDataClass gt

[java] Hashmap holding different data types as values for instance Integer, String and Object

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