How can I turn a list of list into a list in java 8

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  • How can I turn a list of list into a list in java 8

How can I turn a list of list into a list in java 8

How can I turn a list of list into a list in java 8

Sample program for converting list of list into a list in java 8

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class FlatMap {
    public static void main(String[] args) {
        List<List> hobies=new ArrayList<>();

        List<String> person1= Arrays.asList("Cricket", "Football");
        List<String> person2= Arrays.asList("Chess","Cricket", "Golf");
        List<String> person3= Arrays.asList("Reading Book", "Football","Watching TV");
        hobies.add(person1);
        hobies.add(person2);
        hobies.add(person3);

        System.out.println("Adding list of list in single list before java 8");
        List<String> before=new ArrayList<>();
        for(int i=0;i<hobies.size();i++){
            before.addAll(hobies.get(i));
        }
        System.out.println(before);

        System.out.println("Adding list of list in single list using java 8");
        List<String> hibies1=hobies.stream().flatMap(List::stream).collect(Collectors.toList());
        System.out.println(hibies1);

    }
}

OUTPUT

How can I turn a list of list into a list using stream

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