Java HashMap put in an enhanced for loop just like an ArrayList

For example, I can loop an ArrayList like this

for (String temp : arraylist) 

Can I loop a HashMap by using the similar method?

6 Answers

You can iterate over the keys, entries or values.

for (String key : map.keySet()) { String value = map.get(key); } for (String value : map.values()) { } for (Map.Entry<String,String> entry : map.entrySet()) { String key = entry.getKey(); String value = entry.getValue(); } 

This is assuming your map has String keys and String values.

You can't directly loop a Map like that in Java.

You can, however, loop the keys:

for (SomeKeyObject key : map.keySet()) 

The values:

for (SomeValueObject value : map.values()) 

Or even its entries:

for (Map.Entry<SomeKeyObject, SomeValueObject> entry : map.entrySet()) 

you can do

for (String key : hashmap.keySet()) { String value = hashmap.get(key); } 

You can do it by using an Iterator .

 HashMap<String, String> yourHashMap = new HashMap<>(); Iterator<Map.Entry<String, String>> it = yourHashMap.entrySet().iterator(); while(it.hasNext()){ it.next(); System.out.println(yourHashMap.get(it)); } 

At first sight it might be tempting to use a for-loop instead of an Iterator, but

you will need an Iterator if you want to modify the elements in your HashMap while iterating over them!

When using a for-loop you cannot remove elements from your map while

 it.remove() 

would work well in the above example.

public class IterableHashMap<T,U> extends HashMap implements Iterable { @Override public Iterator iterator() { // TODO Auto-generated method stub return this.keySet().iterator(); } } public static void main(String[] args) { testA a=new testA(); IterableHashMap test=a.new IterableHashMap<Object,Object>(); for(Object o:test) { } } 

Use this

map.forEach((k, v) -> System.out.printf("%s %s%n", k, v));