It takes one parameter - the key of the item being accessed. You can use the get() method to access items stored in a HashMap. We added three items, each of them having an integer as a key and a string as their values. To add items to the HashMap, we used the put() method: StudentInfo.put(1, "Ihechikara") We specified the keys as integers while the values were strings: HashMap. In the code above, the HashMap is called StudentInfo. It takes in two parameters - the key and the value of the item being added. To add items to a HashMap, we make use of the put() method. You'll learn how to add, access, remove, and update items in a HashMap. In this section, we'll talk about some of the useful methods that you can use when working with HashMaps. When working with HashMaps, we make use of wrapper classes. This is how HashMaps work.īefore we dive into examples, here's a list of wrapper classes and their corresponding primitive data types in Java: Wrapper Classes and Primitive Types in Java Wrapper classes You'll notice that we're working with wrapper classes and not primitive types when specifying the data types for the keys and values. The keys that will be stored in the HashMap will all be integers while the values will be strings. In the code above, we created a HashMap called StudentInfo. Here's an example to simplify the terms: HashMap StudentInfo = new HashMap() HashMapName denotes the name of the HashMap.ValueDataType denotes the data type of all the values that'll be stored in the HashMap.KeyDataType denotes the data type of all the keys that'll be stored in the HashMap.Let's explain some of the key terms in the syntax above. Here's what the syntax looks like for creating a new HashMap: HashMap HashMapName = new HashMap() In order to create and use a HashMap, you must first import the package. Data types are specified using wrapper classes instead of primitive data types.In a case where there are duplicate keys, the last one will override the other(s).Items do not maintain any order when added.Here are some of the features of a HashMap: What Are the Features of a HashMap in Java?īefore working with HashMaps, it is important to understand how they work. In this article, we'll talk about the features of a HashMap, how to create a HashMap, and the different methods we can use to interact with the data stored in them. You can access items stored in a HashMap using the item's key, which is unique for each item. In Java, you use a HashMap to store items in key/value pairs.
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