dictionary - How do I efficiently iterate over each entry in a Java Map?

Here is a generic type-safe method which can be called to dump any given Map.

import java.util.Iterator;
import java.util.Map;
public class MapUtils {
    static interface ItemCallback {
        void handler(K key, V value, Map map);
    }
    public static  void forEach(Map map, ItemCallback callback) {
        Iterator> it = map.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry entry = it.next();
            callback.handler(entry.getKey(), entry.getValue(), map);
        }
    }
    public static  void printMap(Map map) {
        forEach(map, new ItemCallback() {
            @Override
            public void handler(K key, V value, Map map) {
                System.out.println(key + " = " + value);
            }
        });
    }
}

Example

Here is an example of its use. Notice that the type of the Map is inferred by the method.

import java.util.*;
public class MapPrinter {
    public static void main(String[] args) {
        List> maps = new ArrayList>() {
            private static final long serialVersionUID = 1L;
            {
                add(new LinkedHashMap() {
                    private static final long serialVersionUID = 1L;
                    {
                        put("One", 0);
                        put("Two", 1);
                        put("Three", 3);
                    }
                });
                add(new LinkedHashMap() {
                    private static final long serialVersionUID = 1L;
                    {
                        put("Object", new Object());
                        put("Integer", new Integer(0));
                        put("Double", new Double(0.0));
                    }
                });
            }
        };
        for (Map map : maps) {
            MapUtils.printMap(map);
            System.out.println();
        }
    }
}

Output

One = 0
Two = 1
Three = 3
Object = java.lang.Object@15db9742
Integer = 0
Double = 0.0