CODEWITHSUNDEEP
java
Stella
Stella

Reputation: 1868

Store multiple values in HashMap and get it later

I am storing a data in HashMap and getting the value in later stage.

HashMap<String, byte[]> hm = new HashMap<String, byte[]>();

Now, I want to store two more values into it. For example, I want to store info like below. Could someone please advise me, how can i modify the Hashmap to ahieve this way? I also require to read all these stored values and find some value from it in later stage.

Key 1
    IPAddress
    RandomNumber
    Byte data
Key 2
    IPAddress
    RandomNumber
    Byte data

Thank you!

Upvotes: 0

Views: 2212

Answers (3)

Evgeni Dimitrov
Evgeni Dimitrov

Reputation: 22506

You have to create a class with these properties:

class MyData{
    private String IPAddress;
    private long RandomNumber;
    private byte[] data;

    //getters setters...
}

Map<String, MyData> hm = new HashMap<String, MyData>();

You can get the values as:

MyData dataObj = hm.get("Key 1");
dataObj.getRandomNumber();

or directly

  hm.get("Key 1").getData();
  hm.get("Key 1").getRandomNumber();

To iterate over the map:

    Iterator it = hm.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry myDataEntry = (Map.Entry)it.next();
        System.out.println(myDataEntry.getKey() + " = " + myDataEntry.getValue());
        it.remove(); // avoids a ConcurrentModificationException
    }

Taken from here: Iterate through a HashMap

Upvotes: 2

Olimpiu POP
Olimpiu POP

Reputation: 5067

I see two options for your issue:

1 - make a bean to wrap all the needed content (as advised by other posters)

2 - if you want to have more values for a single key and adding a new library to your project is not an issue you can use google guava library, more particularly the Multimap class. There you can have more values for a single key.

Nevertheless I would advise in writing a java bean that wraps the content you want in a single object.

Upvotes: 0

eltabo
eltabo

Reputation: 3807

Create a class like:

public class Key{
    int randomNumber;
    byte[] data;
    String ipAddress;
}

And store it like a value of your Map.

Map<String, Key> map;

Hope it helps.

Upvotes: 0

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