How to merge two members of a multimap in java?

Question

0.00/5 (No votes)

See more:

I have written a multimap in java and I want to merge two members of this map to each other. the map is as follow:

Map<Integer,Map<Integer,Integer>> groups = new HashMap<>();

for example if group[0] is 0 => {0=1, 1=10} and group[1] is 1 => {0=2, 1=3}, I want the answer be 1 => {0=2, 1=3,2=1, 3=10}. how can I do this?

What I have tried:

I searched about it, but I could not find a proper solution

Posted 10-Aug-17 19:56pm

Member 11807654

Updated 10-Aug-17 22:08pm

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

CPallini · Answer 1 · 2017-08-10T22:08:00

Well, if the wonderful Java libraries don't provide a direct solution, then, you know, you might resort to use development techniques, like iterations, conditional statements and the like...

Java

Set <Integer> s0 = m.get(0).keySet();
Set <Integer> s1 = m.get(1).keySet();

Iterator <Integer> it0 = s0.iterator();
Iterator <Integer> it1 = s1.iterator();


Integer n0 = null;
Integer n1 = null;

Map <Integer, Integer> rm = new HashMap<Integer, Integer>();

int count = 1;

while (true)
{

  if ( n0 == null && it0.hasNext() )
    n0 = m.get(0).get(it0.next());

  if ( n1 == null && it1.hasNext() )
    n1 = m.get(1).get(it1.next());

  if ( n0 == null )
  {
    if (n1 == null)
      break;
    else
    {
      rm.put(count, n1);
      n1 = null;
      ++count;
    }
  }
  else
  {// here n0 != null
    if (n1 == null)
    {
      rm.put(count, n0);
      n0 = null;
      ++count;
    }
    else
    {
      if ( n0 < n1 )
      {
        rm.put(count, n0);
        n0 = null;
        ++count;
      }
      else
      {
        rm.put(count, n1);
        n1 = null;
        ++count;
      }
    }
  }