How can I use the Java Streams API for mapping?

Can you explain how to use the Java Streams API for mapping elements in a list?

Sure! The Java Streams API allows you to transform elements in a collection using the map method. This method applies a function to each element and returns a new stream of the transformed elements.

Can you provide a code example of using the map function?

Absolutely! Here's a simple example:

List<String> names = Arrays.asList("Alice", "Bob", "Charlie");
List<Integer> nameLengths = names.stream()
    .map(String::length)
    .collect(Collectors.toList());

This code maps each name to its length.

What if I want to filter the names before mapping?

You can chain the filter method before map. For example:

List<String> filteredLengths = names.stream()
    .filter(name -> name.startsWith("A"))
    .map(String::length)
    .collect(Collectors.toList());

This will only map names that start with 'A'.

Can I use custom functions in the map method?

Yes, you can use any function that matches the expected input type. For example:

List<Integer> customMapped = names.stream()
    .map(name -> name.length() * 2)
    .collect(Collectors.toList());

This doubles the length of each name.