Re: Iterating over Maps: Am I missing something?

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.help

Date:

Tue, 06 Feb 2007 14:13:19 -0800

Message-ID:

<eqaui0$22t8$1@ihnp4.ucsd.edu>

dsh0105@gmail.com wrote:

I've found that I often need to iterator over a Map and do something
to each element of the Map. The only way I've found to do this is to
get a get a KeySet from the map, get an Iterator from the KeySet and
use that Iterator to move over the elements of the Map. Is their a
simpler (less verbose) way of accomplishing this:

Set<String> keys=myMap.keySet();
Iterator<String>it=keys.iterator();
while (it.hasNext())
{
String key=it.next();
String value=myMap.get(key);
/*
Do something to the value...
*/
}

This just seems like a lot of work when you compare it to what you can
do with a ArrayList (assume this is a list of Strings for example
purposes)
for (String s: myList)
{
//Do something with s
}

Any advice appreciated.

What is preventing you from using the new loop syntax with the Map?

import java.util.HashMap;
import java.util.Map;

public class MapTest {
   public static void main(String[] args) {
     Map<String,String> myMap = new HashMap<String,String>();
     myMap.put("x","a");
     myMap.put("y","b");
     System.out.println("Values only");
     for(String value: myMap.values()){
       System.out.printf("Value: %s%n",value);
     }
     System.out.println("Keys and values");
     for(Map.Entry<String,String> entry: myMap.entrySet()){
       System.out.printf("Key: %s, Value: %s%n",
           entry.getKey(),entry.getValue());
     }
   }
}

Patricia