Comparing Streams to Loops in Java

// Java Program to Compare Streams to Loops 

// Importing required libraries
import java.io.IOException;
import java.lang.String;
import java.nio.file.*;
import java.util.*;
import java.util.Arrays;
import java.util.List;
import java.util.stream.*;

// Main class
// JavaStreams
class GFG {

    // Main driver method
    public static void main(String[] args)
        throws IOException
    {

        // 1. Integer Stream
        System.out.println("Integer Stream : ");
        IntStream.range(1, 10).forEach(System.out::print);

        // New line
        System.out.println();

        // 2. Integer Stream with skip
        System.out.println("Integer Stream with skip : ");
        IntStream.range(1, 10).skip(5).forEach(
            x -> System.out.println(x));

        // New line
        System.out.println();

        // 3. Integer Stream with sum
        System.out.println("Integer Stream with sum : ");
        System.out.println(IntStream.range(1, 5).sum());

        // New line
        System.out.println();

        // 4. Stream.of, sorted and findFirst
        System.out.println(
            "Stream.of, sorted and findFirst : ");
        Stream.of("Java ", "Scala ", "Ruby ")
            .sorted()
            .findFirst()
            .ifPresent(System.out::println);

        // New line
        System.out.println();

        // 5. Stream from Array, sort, filter and print
        String[] names = { "AI",        "Matlab",
                           "Scikit",    "TensorFlow",
                           "OpenCV",    "DeepLearning",
                           "NLP",       "NeuralNetworks",
                           "Regression" };
        System.out.println(
            "Stream from Array, sort, filter and print : ");
        Arrays
            .stream(names) // same as Stream.of(names)
            .filter(x -> x.startsWith("S"))
            .sorted()
            .forEach(System.out::println);

        // New line
        System.out.println();

        // 6. average of squares of an int array
        System.out.println(
            "Average of squares of an int array : ");
        Arrays.stream(new int[] { 2, 4, 6, 8, 10 })
            .map(x -> x * x)
            .average()
            .ifPresent(System.out::println);

        // New line
        System.out.println();

        // 7. Stream from List, filter and print

        // Display message only
        System.out.println(
            "Stream from List, filter and print : ");

        List<String> people = Arrays.asList(
            "AI", "Matlab", "Scikit", "TensorFlow",
            "OpenCV", "DeepLearning", "NLP",
            "NeuralNetworks");
        people.stream()
            .map(String::toLowerCase)
            .filter(x -> x.startsWith("a"))
            .forEach(System.out::println);

        // New line
        System.out.println();

        // 8. Reduction - sum

        // Display message only
        System.out.println("Reduction - sum : ");

        double total
            = Stream.of(7.3, 1.5, 4.8)
                  .reduce(0.0,
                          (Double a, Double b) -> a + b);

        // Print and display
        System.out.println("Total = " + total);

        System.out.println();

        // 9. Reduction - summary statistics
        System.out.println(
            "Reduction - summary statistics : ");
        IntSummaryStatistics summary
            = IntStream.of(7, 2, 19, 88, 73, 4, 10)
                  .summaryStatistics();

        // Print and display
        System.out.println(summary);

        System.out.println();
    }
}

// Java Program to Comparing Streams to Loops

// Importing utility packages
import java.util.*;

// Class 1
// helper class 
class ProgrammingLanguage {

    // Member variables of this class
    int rank;
    String name;
    int value;

    // Member method of this class
    public ProgrammingLanguage(int rank, String name,
                               int value)
    {

        // this keyword is used to refer current object
        // itself
        this.rank = rank;
        this.name = name;
        this.value = value;
    }
}

// Class 2
// JavaStreamExample
public class GFG {

    // MAin driver method
    public static void main(String[] args)
    {

        // Creating an object of List class
        // Declaring object of user defined type (above
        // class)
        List<ProgrammingLanguage> programmingLanguage
            = new ArrayList<ProgrammingLanguage>();

        // Adding elements to the object of this class
        // Custom input entries
        programmingLanguage.add(
            new ProgrammingLanguage(1, "Java", 7000));
        programmingLanguage.add(
            new ProgrammingLanguage(2, "Rust", 2000));
        programmingLanguage.add(
            new ProgrammingLanguage(3, "Ruby", 1500));
        programmingLanguage.add(
            new ProgrammingLanguage(4, "Scala", 2500));
        programmingLanguage.add(
            new ProgrammingLanguage(5, "Groovy", 4000));

        // Creating object of List class of integer type
        List<Integer> languageValueList
            = new ArrayList<Integer>();

        // For each loops for iteration
        for (ProgrammingLanguage language :
             programmingLanguage) {

            // Filtering data of List
            if (language.value < 3000) {

                // Adding price to above elements
                languageValueList.add(language.value);
            }
        }

        // Print and display all elements inside the object
        System.out.println(languageValueList);
    }
}