How do I iterate over a LinkedHashMap and select between the key and value separately?

Question

At the moment I have this:

try{
            // Create file 
            FileWriter fstream = new FileWriter("output");
            BufferedWriter out = new BufferedWriter(fstream);
            Iterator mapIt = assignments.entrySet().iterator();
            while (mapIt.hasNext()){
                out.write(mapIt.next().toString()+";\n");
            }
            //Close the output stream
            out.close();
        }

The thing is, I can't just take the toString() of iterator, I need to take out the key and the value separately so I can put some stuff between them in the outputfile. Does anyone know how I do this?

possible duplicate of [How do I iterate over each Entry in a Collection Map?](http://stackoverflow.com/questions/46898/how-do-i-iterate-over-each-entry-in-a-collection-map) — Graham Borland, Feb 17 '12 at 16:50

score 3 · Accepted Answer · answered Feb 17 '12 at 16:49

3

You will notice the iterator returns a Map.Entry which has getKey and getValue methods.

Use those to get the respective items....something like

while (mapIt.hasNext()){
   Map.Entry entry = mapIt.next();
   Object key = entry.getKey();
   Object value = entry.getValue();
   // format away..
}

Note I put Object as the types of key and val, but you should specify the types according to however you defined the Map.

answered Feb 17 '12 at 16:49

hvgotcodes

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(Hint: generics will make this much less of a pain, and much more self-evident.) – Louis Wasserman Feb 17 '12 at 18:34

score 1 · Answer 2 · answered Feb 17 '12 at 16:49

1

Since the iterator returns a set of Map.Entry, you can get the key and value separately out of that:

http://docs.oracle.com/javase/6/docs/api/java/util/Map.Entry.html

answered Feb 17 '12 at 16:49

duffymo

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score 1 · Answer 3 · edited May 23 '17 at 11:48

1

From How to efficiently iterate over each Entry in a Map?

for (Map.Entry<String, String> entry : map.entrySet())
{
    System.out.println(entry.getKey() + "/" + entry.getValue());
}

edited May 23 '17 at 11:48

Community

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1

answered Feb 17 '12 at 16:49

Graham Borland

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How do I iterate over a LinkedHashMap and select between the key and value separately?

3 Answers3