Compare and merge two TreeMap

**TechGate** · 23-02-2010

Hello,
I have two TreeMap containing key Each person as a String (representing a name) and a Float object as value. Both TreeMap have the same list of key (the same name). I would like to compare my first treemap with the second and I fell on the same key, I want to record the amount of float associated. Do, you have any idea about this, if yes then please help me with it, any suggestion regarding this topic will helpful for me. Thanks in advance.

**Remedy** · 23-02-2010

Hey guys,
I was also trying for a similar kind of a program, but I did not found a solution for it still, this is what i have tired till now
Here is my code

Code:

	Public TreeMap usrprf = new TreeMap(); / / my first treemap
	Public TreeMap prf = new TreeMap(); / / my second treemap

Iterator itUserProfil1 = usrprf.values().iterator(); / / iterator for my first treemap
	Iterator itUserProfil2 = usrprf.keySet().iterator();

Iterator = iprf1 prf.values().iterator(); / / iterator for my second treemap
	Iterator = iprf2 prf.keySet().iterator();
		
		while(itUserProfil2.hasNext()){
			while(iprf2.hasNext()){
                                 
                                / / compare itUserProfil2 and iprf2
                                / / if equal then we add itUserProfil1 and iprf1
 
				}
			}
		}

**InterNetWorKed** · 23-02-2010

Hello,
Normal that you had the error in the following code:

Code:

while(iuprf2.hasNext()){ 
         while(iprf2.hasNext()){ 
                                / / compare iuprf2 and iprf2 
                                / / if equal then we add iuprf1 and iprf1 
                                if(iuprf2.next().equals(iprf2.next()))  {...}
 
            } 
         } 
      }

In effect you take the following iuprf2 element for each iteration in iprfs2 then after some time there has more elements. of error or NoSuchElementException. Are you getting my point.

**Linux-Us** · 23-02-2010

Hello,
It would be better to use the method containsKey (Object)

Code:

Public TreeMap usrprf = new TreeMap();
Public TreeMap prf = new TreeMap();

Iterator iusrprf2 = usrprf.keySet().iterator();
		
while(iusrprf2.hasNext()){
   String key = (String) iusrprf2.next();
   if (prf.containsKey(key)) {
      ...
   }
}

As for the method putAll (Map)You'll lose data if your maps have 2 identical keys.

**TechGate** · 23-02-2010

Hello,
Thank you for your responses. I went to see the API in sun but I can not find a method to do directly what I want. The method putAll () copies all entries in a treemap treemap other. By causing the test I realized that when you insert a key already existing when the former is removed so I can not add the values corresponding. If you have other avenues to explore, you can post it here and help me. Thanks in advance.

**SoftWore** · 23-02-2010

Hello,
I do not know this is going to help you or not, still have a look at the following code.

Code:

Comparator naturalStringOrder=new Comparator()
{
    public int compare(Object o1,Object o2)
    {
        return ((String)o1).compareTo((String)o2);
    }
};
 
Comparator rvstrob=new Comparator()
{
    public int compare(Object o1,Object o2)
    {
        return -((String)o1).compareTo((String)o2);
    }
};