VL-Programmieren/VL13/Aufgabe03/Aufgabe03.java

package VL13.Aufgabe03;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Random;

/**
 * Vorlesung 13 / Aufgabe 3
 *
 * @author Sebastian Brosch
 */
public class Aufgabe03 {
  public static void main(String[] args) {
    final int MAX_RUNS = 10;
    int[] sizes = new int[] { 10000, 20000, 50000, 100000, 200000, 500000, 1000000, 2000000, 5000000, 10000000,
        20000000, 50000000 };

    for (int size : sizes) {
      long sumArrayList = 0;
      long sumLinkedList = 0;
      ArrayList<String> values = getValues(size);

      for (int i = 0; i < MAX_RUNS; i++) {
        sumArrayList += runTestArrayList(values);
        sumLinkedList += runTestLinkedList(values);
      }

      System.out.printf("\nMittelwert (Zeichenketten: %,d):\n", size);
      System.out.printf("  ArrayList: %d Millisekunden\n", (sumArrayList / MAX_RUNS));
      System.out.printf("  LinkedList: %d Millisekunden\n", (sumLinkedList / MAX_RUNS));
    }

    System.out.println("\nAlle Tests wurden beendet.");
  }

  /**
   * Method to run a test using a ArrayList.
   *
   * @param values The values to fill in ArrayList.
   * @return The elapsed time of the test.
   */
  private static long runTestArrayList(ArrayList<String> values) {
    long timeStart = System.currentTimeMillis();
    ArrayList<String> testArrayList = new ArrayList<String>();

    for (String value : values) {
      testArrayList.add(value);
    }

    return System.currentTimeMillis() - timeStart;
  }

  /**
   * Method to run a test using LinkedList.
   *
   * @param values The values to fill in LinkedList.
   * @return The elapsed time of the test.
   */
  private static long runTestLinkedList(ArrayList<String> values) {
    long timeStart = System.currentTimeMillis();
    LinkedList<String> testLinkedList = new LinkedList<String>();

    for (String value : values) {
      testLinkedList.add(value);
    }

    return System.currentTimeMillis() - timeStart;
  }

  /**
   * Method to determine a random number from a certain range.
   *
   * @param start The first number of the range.
   * @param end   The last number of the range.
   * @return A random number from a certain range.
   */
  private static int getRandomNumber(int start, int end) {
    return (new Random()).nextInt((end - start + 1)) + start;
  }

  /**
   * Method to generate a random string.
   *
   * @param min The minimum length of the random string.
   * @param max The maximum length of the random string.
   * @return A random string.
   */
  private static String getRandomString(int min, int max) {
    final String NUMBERS = "0123456789";
    final String UCHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    final String LCHARS = UCHARS.toLowerCase();

    String random = "";
    int length = getRandomNumber(min, max);

    for (int i = 0; i < length; i++) {
      String chars = "";

      switch (getRandomNumber(1, 3)) {
        case 1:
          chars = NUMBERS;
          break;
        case 2:
          chars = UCHARS;
          break;
        case 3:
          chars = LCHARS;
          break;
      }

      int charIndex = getRandomNumber(0, chars.length() - 1);
      random += chars.substring(charIndex, charIndex + 1);
    }

    return random;
  }

  /**
   * Method to get a list with random strings.
   *
   * @param numberOfStrings The amount of random strings to generate.
   * @return A list with random strings.
   */
  private static ArrayList<String> getValues(int numberOfStrings) {
    final int MIN_LENGTH = 10;
    final int MAX_LENGTH = 16;
    ArrayList<String> values = new ArrayList<String>();

    for (int i = 0; i < numberOfStrings; i++) {
      values.add(getRandomString(MIN_LENGTH, MAX_LENGTH));
    }

    return values;
  }
}