Gain insights into Java Collections Framework. Delve into lists, sets, and hashmaps. Learn about data modification, sorting, thread-safety, and internal workings for efficient usage.

Collection is one of the most important topics for Java programming. Without the proper knowledge of every collection type in Java, it becomes difficult for you to decide which option to pick in a particular scenario.

This course will give you a great understanding of all collection types available in the Collections Framework like lists, linked lists, sets, and hashmaps. 

After completing this course, you will know how data can be modified within a collection, how to sort a collection, and how it can be made thread-safe. You will also cover the internal working of each Java collection so you can work with them more efficiently.

Collections in Java

**Arrays** is a class in the `java.utils` package that contains various methods for manipulating arrays (such as sorting and searching). This class also contains a static factory that allows arrays to be seen as a list. The methods in this class throw a `NullPointerException` if the specified array reference is `null`.

## Searching an element in an array

The `Arrays` class provides the `binarySearch()` method to search for a particular element in an array. There are a lot of overloaded `binarySearch()` methods to handle all the primitive types. Some of the important points to note about the `binarySearch()` method are:

1. The array that is passed to the method should be sorted. If the array is not sorted, then the result is undefined.

2. This method returns the index where the element is present in the array. If the element is not present in the array, then the index of the first element greater than the key is returned.

3. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

4. ClassCastException is thrown if the search key is not comparable to the elements of the array.

As the name suggests, the `binarySearch()` method uses the binary search algorithm to search for an element in the array. It is far better than a linear search. The complexity of the linear search algorithm is **O(n)**, whereas the complexity of the binary search algorithm is **O(log n)**.

The below example shows how we can use the `binarySearch()` method to search an element in an integer array.

# Searching an element in an array

The `Arrays` class provides the `binarySearch()` method to search for a particular element in an array. There are a lot of overloaded `binarySearch()` methods to handle all the primitive types. Some of the important points to note about the `binarySearch()` method are:

1. The array that is passed to the method should be sorted. If the array is not sorted, then the result is undefined.

2. This method returns the index where the element is present in the array. If the element is not present in the array, then the index of the first element greater than the key is returned.

3. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

4. ClassCastException is thrown if the search key is not comparable to the elements of the array.

As the name suggests, the `binarySearch()` method uses the binary search algorithm to search for an element in the array. It is far better than a linear search. The complexity of the linear search algorithm is **O(n)**, whereas the complexity of the binary search algorithm is **O(log n)**.

The below example shows how we can use the `binarySearch()` method to search an element in an integer array.

Let's discuss how we can use the binarySearch() method to search an element in an array.

Let's Begin

Lists in Java

LinkedList in Java

CopyOnWriteArrayList in Java

Sets in Java

TreeSet in Java

HashMap In Java

TreeMap in Java

LinkedHashMap in Java

Additional Map Implementations

Arrays Class

Collections Class

Searching an Array

Searching an element in an array