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Archive for the ‘Collections API’ Category

Iterating a HashMap

Here is a quick example that shows how to iterate over a HashMap.

You have the option of using the map key set or the map entry set.

 

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class HashDemo {
public static void main(String[] args) {
Map<String, String> theMap = new HashMap<String, String>();
theMap.put("alfa", "john");
theMap.put("beta", "mary");
theMap.put("code", "susan");
// iterate using keys
System.out.println("Using Key set");
Set<String> theKeys = theMap.keySet();
for (String tempKey : theKeys) {
String tempValue = theMap.get(tempKey);
System.out.println("key: " + tempKey + ", value: " + tempValue);
}
// iterator using Map.Entry
System.out.println("\nUsing Map.Entry");
Set<Map.Entry<String, String>> theMapEntries = theMap.entrySet();
for (Map.Entry<String, String> tempEntry : theMapEntries) {
System.out.println("key: "  + tempEntry.getKey() + ", value: "  + tempEntry.getValue());
}
}
}
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