What is equivalent to C#'s Select clause in JAVA's streams API

Question

I wanted to filter list of Person class and finally map to some anonymous class in Java using Streams. I am able to do the same thing very easily in C#.

Person class

Answer 1

If you want to create a list of new Person instances you first should provide a constructor, e.g. like this:

class Person {
  public int id;
  public String name;
  public String address;

  public Person( int pId, String pName, String pAddress ) {
    super();
    id = pId;
    name = pName;
    address = pAddress;
  }
}

Then you could use the stream:

List lst = new ArrayList<>();

lst.add(new Person(1, "Pava", "India" ));
lst.add(new Person( 2, "tiwari", "USA" ) );

//since id is an int we can't use null and thus I used -1 here    
List result = lst.stream().map(p -> new Person(-1, p.name, p.address)).collect(Collectors.toList());

If you want to filter persons then just put a filter() in between stream() and map():

List result = lst.stream().filter(p -> p.name.startsWith( "P" )).map(p -> new Person( -1, p.name, p.address )).collect(Collectors.toList());