Built-in data structures

import java.util.ArrayList;
import java.util.List;

public class ExampleList {
    public static void main(String[] args) {
        List<Integer> T = new ArrayList<>();
        T.add(1);
        T.add(2);
        T.add(3);
        T.add(4);
        T.add(5);

        System.out.println("Initial list: " + T + " with ref " + System.identityHashCode(T));

        T.add(6); // Appending an integer instead of a string
        T.set(0, 2); // Modifying the first element

        System.out.println("Modified list: " + T + " still with ref " + System.identityHashCode(T));
        System.out.println("Two last elements: " + T.subList(T.size() - 2, T.size()));
    }
}

import java.util.HashSet;
import java.util.Set;

public class ExampleSet {
    public static void main(String[] args) {
        Set<Integer> T = new HashSet<>();
        T.add(1);
        T.add(3);
        T.add(5);
        T.add(5); // Duplicate element, will not be added

        System.out.println("Initial set: " + T + " with hash code " + System.identityHashCode(T));
        T.add(6);
        System.out.println("Modified set: " + T + " with hash code " + System.identityHashCode(T));
        System.out.println("Contains 4: " + T.contains(4));
    }
}

import java.util.Arrays;

public class ExampleTuple {
    public static void main(String[] args) {
        Object[] T = {1, "3", 3.14};
        System.out.println("Initial tuple: " + Arrays.toString(T) + " with hash code " + System.identityHashCode(T));
        System.out.println("Second element: " + T[1]);
        
        Object[] newT = Arrays.copyOf(T, T.length + 1);
        newT[newT.length - 1] = "4";
        System.out.println("New tuple: " + Arrays.toString(newT) + " with hash code " + System.identityHashCode(newT));
    }
}

// Needed imports
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * To run this code, you need to have Java installed on your computer, then:
 * - Create a file named `Main.java` in a directory of your choice.
 * - Copy this code in the file.
 * - Open a terminal in the directory where the file is located.
 * - Run the command `javac Main.java` to compile the code.
 * - Run the command `java -ea Main` to execute the compiled code.
 * Note: '-ea' is an option to enable assertions in Java.
 */
public class Main {

    /**
     * This function was translated from the Python code.
     * This is also the case for the contents of the "main" function.
     *
     * @param text The text to index.
     * @return     The dictionary containing the indexes of all the words in the text.
     */
    public static Map<String, List<Integer>> indexWords(String text) {
        // Split the text into words
        String[] words = text.split("\\s+");
        // Create a map to store the indexes
        Map<String, List<Integer>> indexes = new HashMap<>();

        // Loop over the words and populate the index map
        for (int i = 0; i < words.length; i++) {
            String word = words[i];
            // If the word is not yet in the map, add it
            if (!indexes.containsKey(word)) {
                indexes.put(word, new ArrayList<>());
            }
            // Append the current index to the list
            indexes.get(word).add(i);
        }

        return indexes;
    }

    /**
     * This is the entry point of your program.
     * It contains the first codes that are going to be executed.
     *
     * @param args Command line arguments received.
     */
    public static void main(String[] args) {
        // Let's test the method
        String text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed lacinia, nibh a tincidunt luctus, tortor nunc molestie ante, ut egestas est sapien quis orci. Nunc laoreet eget ipsum id rhoncus. Curabitur vel nibh bibendum, eleifend nibh gravida, tempus massa. Donec id felis blandit, pretium nisl ut, sagittis ligula. Curabitur vitae accumsan ex. Pellentesque interdum condimentum sem, eu aliquet arcu mollis ac. Mauris pellentesque lobortis mi, eget aliquam mauris gravida vel. Nulla quis dui vel arcu malesuada vulputate. Praesent nisi ex, tincidunt fermentum augue eu, cursus vehicula ipsum. Nam vel diam gravida, ultrices eros sed, cursus libero. Etiam maximus tincidunt metus in maximus.";
        Map<String, List<Integer>> index = indexWords(text);
        System.out.println(index);
    }

}

{mollis=[59], ante,=[17], sem,=[55], vel.=[69], adipiscing=[6], est=[20], cursus=[84, 94], eleifend=[34], accumsan=[50], Pellentesque=[52], egestas=[19], augue=[82], nunc=[15], mi,=[64], orci.=[23], mauris=[67], maximus.=[101], id=[28, 40], Nulla=[70], molestie=[16], vel=[31, 73, 88], elit.=[7], ut=[18], lobortis=[63], Etiam=[96], luctus,=[13], in=[100], lacinia,=[9], fermentum=[81], vulputate.=[76], sed,=[93], eu=[56], Sed=[8], pellentesque=[62], vitae=[49], ipsum=[1, 27], amet,=[4], felis=[41], Curabitur=[30, 48], laoreet=[25], tempus=[37], Mauris=[61], ac.=[60], arcu=[58, 74], dolor=[2], bibendum,=[33], metus=[99], rhoncus.=[29], ex,=[79], vehicula=[85], ex.=[51], diam=[89], sit=[3], interdum=[53], a=[11], nisi=[78], tortor=[14], blandit,=[42], tincidunt=[12, 80, 98], nisl=[44], ipsum.=[86], ultrices=[91], condimentum=[54], aliquam=[66], massa.=[38], ut,=[45], Praesent=[77], nibh=[10, 32, 35], gravida,=[36, 90], Donec=[39], libero.=[95], Lorem=[0], aliquet=[57], malesuada=[75], pretium=[43], sapien=[21], Nunc=[24], dui=[72], quis=[22, 71], Nam=[87], eu,=[83], consectetur=[5], eget=[26, 65], sagittis=[46], ligula.=[47], gravida=[68], eros=[92], maximus=[97]}