Common Scenario Code Examples of Lambda in java

In this paper, we share the specific codes of Lambda commonly used scenarios in java for your reference. The specific contents are as follows

public class test18 {
  /**
   * lambda Common scenarios for expressions 
   */
  @Test
  public void test() {
    List<String> list_one = new ArrayList<>();
    list_one.add("NIKE");
    list_one.add("Addidas");
    /**
     *  Abbreviation for anonymous inner classes  ()->
     */
    new Thread(new Runnable() {
      @Override
      public void run() {
        System.out.println("do nothing");
      }
    }).start();
    new Thread(() -> System.out.println("do nothing")).start();
 
    // Used in set comparators 
    Collections.sort(list_one, new Comparator<String>() {
      @Override
      public int compare(String o1, String o2) {
        return o1.compareTo(o2);
      }
    });
    Collections.sort(list_one, (o1, o2) -> o1.compareTo(o2));// Positive order 
    Collections.sort(list_one, (o1, o2) -> -o1.compareTo(o2));// Reverse order 
 
    // Used to traverse a collection   Or manipulate elements in the collection 
    list_one.forEach(System.out::println);
    List result = new ArrayList();
    list_one.stream().forEach(item -> result.add(item));
 
 
    System.out.println("--boundary--");
 
    // Through customization filter Method   Or   Set .stream().filter(Predicate<>)
    filter(list_one, n -> n.startsWith("N"));
    filter(list_one, n -> true);
    filter(list_one, n -> false);
    filter(list_one, n -> n.length() > 5);
 
    Predicate<String> predicate = n -> n.startsWith("N");
    list_one.stream().filter(predicate).forEach(System.out::print);
    List<Integer> list3 = new ArrayList<>();
    list3.add(10);
    list3.add(8);
    list3.add(3);
    list3.add(15);
    list3.add(20);
    Predicate<Integer> predicate1 = n -> Integer.valueOf(n) > 10;
 
    // Used for map reduce Medium   Here first filter Delete data   Then execute map Operation 
    Double aDouble = list3.stream().filter(predicate1).map(vo -> vo * .12 + vo).reduce((sum, vo) -> sum + vo).get();
    System.out.println(aDouble);
 
    //stream() After that, you can pass distinct() Weight removal   It can also be passed through stream().collect(Collectors.toSet()) Weight removal  
    //Collector.joining(delimiter) Connecting into strings by delimiters 
    List<String> list4 = new ArrayList<>();
    list4.add("Hello");
    list4.add("Boy");
    list4.add("How");
    list4.add("Are");
    list4.add("You");
    list4.add("You");
    list4.stream().distinct().collect(Collectors.toList()).forEach(System.out::print);
    System.out.println(list4.stream().map(x -> x.toUpperCase()).collect(Collectors.joining(", ")));
 
    /**
     *  Pass mapTOInt() mapToDouble() mapToLong()  And then summarStatistics()  Available  IntSummaryStatistics  An instance of this class 
     *  And then call its getSum() getAverage() getCount() getMax() getMin() Method 
     */
    List<Integer> list5 = Arrays.asList(1, 3, 4, 5, 6, 7, 10, 23);
    IntSummaryStatistics intSummaryStatistics = list5.stream().mapToInt(x -> x).summaryStatistics();
    System.out.println(intSummaryStatistics.getSum());
    System.out.println(intSummaryStatistics.getAverage());
    System.out.println(intSummaryStatistics.getCount());
    System.out.println(intSummaryStatistics.getMax());
    System.out.println(intSummaryStatistics.getMin());
  }
 
  public void filter(List<String> names, Predicate<String> condition) {
    names.stream().filter(name -> condition.test(name)).forEach(vo -> System.out.print(vo + " "));
    System.out.println();
  }
}