Main.java

package modern.challenge;

import java.util.concurrent.TimeUnit;

public class Main {

    private static final String TEXT = "My high school, the Illinois Mathematics and Science Academy, "
            + "showed me that anything is possible and that you're never too young to think big. "
            + "At 15, I worked as a computer programmer at the Fermi National Accelerator Laboratory, "
            + "or Fermilab. After graduating, I attended Stanford for a degree in economics and "
            + "computer science.";

    // Ӝ -> Unicode: \u04DC, Code Point: 1244
    // 💕 -> Unicode: \uD83D\uDC95, Code Point: 128149
    private static final String TEXT_CP = "😍 💕 I Ӝ love you Ӝ so much 😍";

    public static void main(String[] args) {

        System.out.println("Input text: \n" + TEXT + "\n");

        System.out.println("\n\nASCII or 16 bits Unicode characters (less than 65,535 (0xFFFF)) examples:\n");

        System.out.println("Loop and break solution:");
        long startTimeV1 = System.nanoTime();

        char firstcharV1 = Strings.firstNonRepeatedCharacterV1(TEXT);

        displayExecutionTime(System.nanoTime() - startTimeV1);
        System.out.println("Found character: " + firstcharV1);

        System.out.println();
        System.out.println(" 256 ASCII codes solution:");
        long startTimeV2 = System.nanoTime();

        char firstcharV2 = Strings.firstNonRepeatedCharacterV2(TEXT);

        displayExecutionTime(System.nanoTime() - startTimeV2);
        System.out.println("Found character: " + firstcharV2);

        System.out.println();
        System.out.println("LinkedHashMap based solution:");
        long startTimeV3 = System.nanoTime();

        char firstcharV3 = Strings.firstNonRepeatedCharacterV3(TEXT);

        displayExecutionTime(System.nanoTime() - startTimeV3);
        System.out.println("Found character: " + firstcharV3);

        System.out.println();
        System.out.println("Java 8, functional-style solution:");
        long startTimeV4 = System.nanoTime();

        char firstcharV4 = Strings.firstNonRepeatedCharacterV4(TEXT);

        displayExecutionTime(System.nanoTime() - startTimeV4);
        System.out.println("Found character: " + firstcharV4);

        System.out.println("\n---------------------------------------------\n");
        
        System.out.println("Input text: \n" + TEXT_CP + "\n");
        
        System.out.println("\n\nIncluding Unicode surrogate pairs examples:\n");

        System.out.println();
        System.out.println("Java 8, functional-style solution:");
        long startTimeV5 = System.nanoTime();

        String firstcharV5 = Strings.firstNonRepeatedCharacterVCP4(TEXT_CP);

        displayExecutionTime(System.nanoTime() - startTimeV5);
        System.out.println("Found character: " + firstcharV5);
    }

    private static void displayExecutionTime(long time) {
        System.out.println("Execution time: " + time + " ns" + " ("
                + TimeUnit.MILLISECONDS.convert(time, TimeUnit.NANOSECONDS) + " ms)");
    }
}