What is the purpose of collectors.toMap in Java?
Collectors.toMap is a terminal operation in the Java Stream API that collects elements from a stream into a Map.
Specifically, Collectors.toMap can take two parameters to achieve different functionalities:
- A function used to extract keys from a Map
- a function for extracting values from a Map
These two functions can be either lambda expressions or method references.
When using Collectors.toMap, each element in the stream will be processed by these two functions, and the results will be added as key-value pairs to the generated Map.
If there are duplicate keys in the stream of elements, you can use an additional parameter to specify how to handle this situation, such as by merging values or throwing an exception.
The return value of Collectors.toMap is a Collector, which can be used with the collect method of a Stream.
