ImperativeVsDeclarative2.java

package com.codecafe.java8.codingstyles;

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

public class ImperativeVsDeclarative2 {

  public static void main(String[] args) {

    // Remove duplicates from a list of Integers

    /* Imperative Approach -- how to achieve the result ? */

    List<Integer> integerList = Arrays.asList(1, 2, 3, 3, 4, 5, 3, 4, 1, 6, 7, 6, 8, 9, 2, 8, 10, 10, 2, 3, 4, 1, 1, 1);

    List<Integer> uniqueList = new ArrayList<>();

    for (Integer integer : integerList) {
      if (!uniqueList.contains(integer)) {
        uniqueList.add(integer);
      }
    }

    System.out.println("Unique List with Imperative approach : " + uniqueList);

    /* Declarative Approach -- What result to achieve ? */

    List<Integer> uniqueList1 = integerList.stream()
                                           .distinct()
                                           .collect(Collectors.toList());

    System.out.println("Unique List with Imperative approach : " + uniqueList1);
  }

}