Let's have a look at the sixth question with also over 3.6 million views over the years, and it is iterate through a hashmap. Let's first have a look what is a map? A map is an interface, as you can see here, located in the Java util package. And a map is a mound of key value pairs or a set of key value pairs. And as every set a set is unordered, so a map is not ordered. And yeah, so you have a set of several key value pairs.

And as you can see, map is generic with two parameters. The first one is the value or the data type of the keys with K And the second one is the data type for values. And each key value pair is called entry. And each entry is described by an interface. It's an interface located in the interface map. And it is code called java.

Util. Map entry. So let's have a look. Sorry. Close all so let's quickly open the interface map. And yeah, you can use it a map entry key value pair and so on.

And every entry has got key, get value, and so on comparing methods and so on. So but it's only an interview So it's a description of it. And yeah, every map, like ash map and other maps, we will take a look after it, which maps, concerts and so on. But every map regardless which which implementation of map has three different ways to iterate through it. So the first way is to iterate through all entries. It's a method entry set is located here.

And to get as recite to get on set, so it is unordered, as I said, and yeah, if you want each key value pair on its own, you have to use the entry set method. Then you get an N Set as recite of the GT entries, so but if you only want to iterate over the keys of the map, so you don't want to see the values and the key value pairs itself, you only want the keys then you could use the keys set method and you get a set of the type k for the keys. And if you want only to see the values, you could use the values method to get a collection of type v. So, it depends what you want. If you iterate over the all through the entries of the key value pairs, you have to do this. And for each entry, you can you can ask the entry please give me your key or please give me your value or your only iterate over the Keys order values.

Yeah, as you want. So the question is iterate through a hashmap. I think the question would be better iterate through a map, because it doesn't matter if you have a hash map, a tree map, Link map, whatever. The iteration through a map is always the same, because the necessary methods that you need to iterate through the whatever map are placed in the interface map. So the question could be iterates through map, it doesn't matter if it is a hash map or something like this. But as I write here, I think hash map is maybe the most used implementation of map.

So there are different kinds of maps. But yeah, the hash map is maybe the most the most used map on its own. So, yeah, let's have a quick look what maps Do we have opened. So you can, you can mark the word map, and then you go to four OpenType hierarchy. And then you get the type hierarchy of map, or you can go navigate, open type in hierarchy. And then you can type that in it.

And you hit the enter key. I go here, yeah, and as you can see, on the route, map interface, there are different other implementations of the map. For example, map. And abstract map on its own has a bunch of implementations or extensions. And you can see the hash map here. So as I, as I showed in the script here, hashmap is an extension of our abstract map.

And here the object. And the abstract map itself is, as the name suggests, is an abstract class. But it's a an implementation of the the map interface. So there are a few things like the simply entry class that implements the the entry interface of map. And abstract map itself, as I said, is an implementation of the map and so on. And so then the hash map is not Special implementation of the abstract or extension of the abstract map.

But for example, you couldn't find an implementation. Another implementation for for the entry itself. So the hashmap uses the implementation of entry from abstract map. But as you can see in there are a few different things. It is Yeah, it is using the hash code to store the things in it. That's why the name hash map is Oh, it's come from, but yeah, as a set duration, how you iterate through a map.

It doesn't. Yeah, it is. It doesn't matter if it is the hash map or whatever. So let's have a look at an example. For iterating through a map I have written a method iterates through a map, it's a static one. So I don't need an instance of the class.

And I have a as parameter I have a map with two question mark. So regardless of which data type it is, the key value doesn't matter. I just want to system out print line them, I want to or I want to iterate, iterate through, so it doesn't matter if they The key is in string, integer, whatever, doesn't matter. So I have a map. And I am using the for each loop here. And I call it map dot entry set.

And this returns the whole entry set. As you as we saw here, the whole set of entries of the map and Each map dot entry element, I can make something with the with each entry. And for this one I output the get key and the get value. So first a key then the value. And this looks like this string. And as you can see, it doesn't matter which concrete implementation you are using if you are using a hash map, a tree map, or whatever, you just saw how many implementations interface map have and yeah, in this case, I am I'm using the hash map, I filled a hash map with with several inputs and call it read through map and get an output this below.

After that, I am creating a tree map And fill it with with elements and iterate through and call the method with the tree map. And it also iterates through the map. Yeah. So that's how the iteration on maps work, and how what a map especially is, what is the interface and what is the hash map and so on. And yeah, this is it. Let's have a look at the next question.