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The hash map is another useful collection type.

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Array List and Hashmat are collection types, the main differences, every entry in an array list is

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one value.

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Every entry and a Hashmat is a pair of data.

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In this lesson, you will learn to use Hashmat.

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Inside your Java bootcamp, resources open up the folder for this lesson by following this path.

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A hash map stores key value pairs.

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The hash map is useful when there's parity between data, every entry and a hash map is a key value

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pair.

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Every key is like a variable that points to a value, for example, short is 499.

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Pens are twelve ninety nine and shoes are twenty three ninety nine.

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To create a hash map, you need to write the class type hash map and inside a generic the find that

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type of each key, the type of each value.

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And remember that generics do not accept primitive types.

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And the third step is to make space for a new object of the heightmap class.

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All right, inside key values Java, there are two arrays, one is an array of vegetables, the other

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is an array of prices.

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There is parity between each element in both the race.

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So instead of having to erase create a new object of the Hashmat class.

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Every key in the hash map is a string, and each value is going to be a double.

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And I'm going to call the heightmap items.

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Hash maps have a method called put, and you can use it to put an entry into the hash map.

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Inside main, we're going to put three entries into the hash map.

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The first entry we're going to put is cauliflower with a price of four point ninety nine.

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This looks a lot better to me.

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I'll play some breakpoints and run the debugger.

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And as you can see, every entry in the hash map is a key value pair.

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Hazmats also have a method.

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Get allows you to access a value from the hash map using its key.

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So inside mean I can get the price of cauliflower.

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I can get the price of spaghetti squash and I can get the price of parsley.

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I'll print each price.

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And run the code.

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And as you can see, get returns, the price of each key.

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Hash map entries don't have an order when you add a new entry, it's placement is random.

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That's why house maps don't have an index number, you can't index a value in a Hashmat.

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You can only get a value using its key.

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So inside key values that Java, I can run through every entry in the hash map using for each.

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For each expecta lambda expression, the lambda for this, for each receives every key value pair.

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And once again, an arrow points to a block of code where we can just print.

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Kee Colon.

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Followed by the value.

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You'll notice they appear in a random order, we added spaghetti squash second, but it appears last.

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Put can add or update an entry.

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It adds an entry if the key doesn't already exist.

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It updates an entry if the key already exists.

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Inside Kivel Java, if you add another entry where the key is partially.

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It's just going to update the price for Pursley.

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There you go.

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Now it's three ninety nine.

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Let's recap in this lesson, you learn to create a hash map.

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And a hash map is useful when there's parity between data, every entry and a hash map is a key value

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pair.

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You can use the put method to add a new entry or update an existing one.

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Finally, hash maps don't have an order, so you can't index a value from a hash map, but you can use

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the get method to get a value based on its key.