Java SE 8 Lambdas and Streams - Java: How to Program Early Objects - page 746

case, we use streams to sort the values in greaterThan4 , collect the results into a new
List<Integers> and display the sorted values.

17.5 Stream<String> Manipulations
[This section demonstrates how lambdas and streams can be used to simplify programming
tasks that you learned in Chapter 14, Strings, Characters and Regular Expressions.]
Figure 17.7 performs some of the same stream operations you learned in Sections 17.3-
17.4 but on a Stream<String> . In addition, we demonstrate case-insensitive sorting and
sorting in descending order. Throughout this example, we use the String array strings
(lines 11-12) that's initialized with color names—some with an initial uppercase letter.
Line 15 displays the contents of strings before we perform any stream processing.

1 // Fig. 17.7: ArraysAndStreams2.java

2 // Demonstrating lambdas and streams with an array of Strings.

3 import java.util.Arrays;

4 import java.util.Comparator;

5
6
7

import java.util.stream.Collectors;

public class ArraysAndStreams2

8

{

9

public static void main(String[] args)

10 {

11 String[] strings =

12 { "Red" , "orange" , "Yellow" , "green" , "Blue" , "indigo" , "Violet" };

13
14 // display original strings

15 System.out.printf( "Original strings: %s%n" , Arrays.asList(strings));

16
17 // strings in uppercase

18 System.out.printf( "strings in uppercase: %s%n" ,

19 Arrays.stream(strings)

20 .map(String::toUpperCase)

21 .collect(Collectors.toList()));

22
23 // strings less than "n" (case insensitive) sorted ascending

24 System.out.printf( "strings greater than m sorted ascending: %s%n" ,

25 Arrays.stream(strings)

26 .filter(s -> s.compareToIgnoreCase( "n" ) < 0 )

27 .sorted( String.CASE_INSENSITIVE_ORDER )

28 .collect(Collectors.toList()));

29
30 // strings less than "n" (case insensitive) sorted descending

31 System.out.printf( "strings greater than m sorted descending: %s%n" ,

32 Arrays.stream(strings)

33 .filter(s -> s.compareToIgnoreCase( "n" ) < 0 )

34 .sorted( String.CASE_INSENSITIVE_ORDER .reversed())

35 .collect(Collectors.toList()));

36 }

37 } // end class ArraysAndStreams2

Fig. 17.7 | Demonstrating lambdas and streams with an array of String s. (Part 1 of 2.)