Java - Issue retrieving value from hashtable

Question

I have a hashtable created:

Hashtable next_hop = new Hashtable();

I insert values like next_hop.put("R1","local") and so on...

The hashtable looks like this:

{R5=R5, R4=R2, R3=R2, R2=R2, R1=Local}

Now I try to retrieve the values from the keys as follows:

String endPoint = "R1";
for (Object o: next_hop.entrySet()) {
   Map.Entry entry = (Map.Entry) o;
   if(entry.getKey().equals(endPoint)){
       String nextHopInt = entry.getValue();
    }
}

i get the following error: error: incompatible types String nextHopInt = entry.getValue();

required: String

found: Object

score 6 · Accepted Answer · answered Apr 11 '16 at 15:06

6

The method getValue() returns an object, not a string, hence the error you are getting. You can cast the value by saying

String nextHopInt = (String) entry.getValue();

answered Apr 11 '16 at 15:06

Rabbit Guy

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2

awesome...that works! – hnvasa Apr 11 '16 at 15:10
6

Also worth noting that `Hashtable` is very deprecated at this point and OP should be using `HashMap` instead. And to avoid this casting mess, it should be parameterized as `HashMap` – TayTay Apr 11 '16 at 15:10

score 0 · Answer 2 · answered Apr 11 '16 at 15:12

0

You have to explicitly cast the RHS if it is a downcast (Object -> String).

String nextHopInt = (String)entry.getValue();

answered Apr 11 '16 at 15:12

James Wierzba

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Java - Issue retrieving value from hashtable

2 Answers2