Java introduction BwInf-Camp 2020

README.md

Goals: being able to ...

• ... write smallish programs with 2 to 3 functions and different control structures
• ... use one IO operation
• ... use Eclipse for running your code

Team-Coding

To learn the basics of the syntax, we'll jointly develop FizzBuzz. To explain FizzBuzz, you can at first play it in real life.

What's important in this exercise:

• System.out.println
• functions
• main
• for what we do, you can ignore static void and classes

Now the students are tasked with two exercises they'll do on their own.

Exercise 1

Goals:

• get to know data types and syntax
• learn one kind of loop
• learn to use functions

Exercise: compute nth Prime.

class NthPrime {

  static boolean isPrime(int potentialPrime) {
    int limit = Math.sqrt(n);

    for (int i = 2; i < limit; i++) {
      if (potentialPrime % i == 0) {
        return false;
      }
    }

    return true;
  }

  static int getNthPrime(int n) {
    int i = 2;
    while (n > 0) {
      if (isPrime(i)) {
        n--;
      }

      i++;
    }

    return i;
  }

  public static void main(String... args) {
    int n = 20;
    int nThPrime = getNthPrime(n);
    System.out.println(n + "th Prime: " + nThPrime);
  }

}

Exercise 2

Goals:

• get to know Strings
• reading files

Task: Read in input.txt. Collect some stats on the age: minimum, maximum, median. If your students are fast, they can do the following:

• compute the average (they need to sort first)
• use Lists instead of arrays

mögl. Lösung:

class AgeStatistics {

  List<String> readFile() {
    String filePath = "./data.txt";
    Scanner scanner = new Scanner(new File(filePath));

    // maybe use String[] with very big size? May be easier to understand
    List<String> result = new ArrayList<String>();

    while (scanner.hasNext()) {
      String line = scanner.next();
      result.add(result);
    }

    return result;
  }

  List<Integer> extractAges(List<String> lines) {
    List<Integer> result = new ArrayList<Integer>();

    for (String line : lines) {
      String[] parts = line.split(",");
      String ageString = parts[2];
      Integer age = Integer.parseInt(ageString);
      result.add(age);
    }

    return result;
  }

  void printStats(List<Integer> ints) {
    int min = list.get(0);
    int max = list.get(0);
    int sum = 0;

    for (Integer x : ints) {
      sum += x;

      if (x < min) {
        min = x;
      }

      if (x > max) {
        max = x;
      }
    }

    System.out.println("Min: " + min);
    System.out.println("Max: " + max);
    System.out.println("Avg: " + sum / ints.size);
  }
  
  public static void main(String... args) {
    String[] lines = readFile();
    List<Integer> ages = extractAges(lines);
    printStats(ages);
  }

}

input.txt

female,[email protected],39
male,[email protected],56
female,[email protected],65
female,[email protected],36
male,[email protected],35
male,[email protected],36
male,[email protected],29
male,[email protected],68
male,[email protected],60
female,[email protected],65
male,[email protected],24
female,[email protected],73
female,[email protected],27
male,[email protected],39
female,[email protected],76
male,[email protected],71
female,[email protected],48
male,[email protected],56
male,[email protected],59
male,[email protected],24
female,[email protected],26
female,[email protected],67
female,[email protected],37
female,[email protected],40
female,[email protected],28
female,[email protected],40
female,[email protected],61
female,[email protected],68
male,[email protected],59
female,[email protected],37
female,[email protected],57
male,[email protected],55
female,[email protected],26
male,[email protected],68
male,[email protected],31
male,[email protected],73
male,[email protected],47
female,[email protected],48
male,[email protected],52
male,[email protected],28
female,[email protected],34
male,[email protected],56
male,[email protected],75
female,[email protected],24
female,[email protected],54
male,[email protected],47
female,[email protected],51
female,[email protected],69
female,[email protected],37
female,[email protected],25
male,[email protected],24
female,[email protected],56
female,[email protected],62
female,[email protected],29
female,[email protected],50
male,[email protected],58
female,[email protected],48
female,[email protected],42
female,[email protected],66
male,[email protected],50
male,[email protected],54
female,[email protected],57
female,[email protected],29
male,[email protected],36
female,[email protected],57
female,[email protected],72
male,[email protected],49
male,[email protected],53
female,[email protected],72
male,[email protected],44
male,[email protected],47
male,[email protected],69
male,[email protected],49
female,[email protected],26
female,[email protected],73
female,[email protected],50
female,[email protected],59
male,[email protected],65
female,[email protected],43
female,[email protected],37
female,[email protected],72
male,[email protected],60
female,[email protected],23
male,[email protected],45
female,[email protected],50
female,[email protected],43
male,[email protected],29
female,[email protected],50
male,[email protected],70
male,[email protected],28
male,[email protected],74
male,[email protected],22
female,[email protected],25
female,[email protected],39
male,[email protected],37
male,[email protected],35
female,[email protected],42
male,[email protected],64
male,[email protected],56
male,[email protected],47
female,[email protected],62
male,[email protected],39
female,[email protected],37
female,[email protected],51
female,[email protected],49
female,[email protected],24
male,[email protected],32
male,[email protected],37
female,[email protected],28
female,[email protected],46
male,[email protected],54
female,[email protected],52
female,[email protected],65
male,[email protected],44
female,[email protected],33
male,[email protected],38
male,[email protected],30
male,[email protected],73
male,[email protected],26
female,[email protected],55
female,[email protected],61
male,[email protected],29
male,[email protected],33
male,[email protected],57
female,[email protected],55
male,[email protected],30
female,[email protected],70
female,[email protected],58
female,[email protected],63
female,[email protected],55
male,[email protected],44
male,[email protected],50
female,[email protected],29
male,[email protected],67
female,[email protected],58
female,[email protected],27
male,[email protected],26
female,[email protected],74
female,[email protected],52
male,[email protected],48
male,[email protected],47
male,[email protected],31
male,[email protected],58
female,[email protected],51
female,[email protected],61
female,[email protected],23
female,[email protected],54
female,[email protected],44
male,[email protected],64
male,[email protected],60
female,[email protected],74
female,[email protected],26
female,[email protected],71
male,[email protected],58
male,[email protected],36
male,[email protected],62
male,[email protected],45
male,[email protected],51
female,[email protected],72
male,[email protected],70
male,[email protected],72
female,[email protected],61
male,[email protected],64
male,[email protected],23
male,[email protected],62
female,[email protected],31
male,[email protected],39
female,[email protected],23
female,[email protected],65
male,[email protected],22
female,[email protected],27
male,[email protected],38
female,[email protected],44
male,[email protected],30
male,[email protected],30
female,[email protected],34
female,[email protected],76
male,[email protected],34
female,[email protected],53
female,[email protected],28
male,[email protected],22
female,[email protected],69
male,[email protected],57
male,[email protected],34
female,[email protected],54
male,[email protected],45
male,[email protected],68
female,[email protected],63
female,[email protected],39
female,[email protected],65
male,[email protected],49
male,[email protected],23
female,[email protected],69
male,[email protected],28
male,[email protected],69
female,[email protected],65
female,[email protected],61
female,[email protected],70
female,[email protected],71
female,[email protected],64
male,[email protected],41
female,[email protected],39
female,[email protected],74
female,[email protected],59
female,[email protected],69
female,[email protected],24
male,[email protected],67
female,[email protected],51
male,[email protected],46
male,[email protected],48
male,[email protected],45
female,[email protected],35
female,[email protected],31
female,[email protected],65
female,[email protected],30
male,[email protected],55
male,[email protected],60
female,[email protected],51
male,[email protected],46
female,[email protected],59
female,[email protected],23
female,[email protected],59
male,[email protected],64
female,[email protected],54
female,[email protected],69
male,[email protected],67
female,[email protected],37
male,[email protected],73
female,[email protected],55
male,[email protected],70
male,[email protected],70
female,[email protected],39
male,[email protected],70
female,[email protected],50
male,[email protected],59
male,[email protected],67
male,[email protected],37
female,[email protected],69
male,[email protected],75
male,[email protected],41
female,[email protected],54
male,[email protected],71
male,[email protected],24
male,[email protected],53
female,[email protected],59
female,[email protected],48
female,[email protected],26
female,[email protected],67
male,[email protected],45
female,[email protected],62
female,[email protected],42
female,[email protected],51
female,[email protected],69
female,[email protected],23
female,[email protected],43
female,[email protected],56
female,[email protected],44
male,[email protected],61
female,[email protected],34
female,[email protected],53
male,[email protected],55
female,[email protected],76
female,[email protected],35
female,[email protected],69
male,[email protected],48
male,[email protected],28
male,[email protected],50
female,[email protected],59
female,[email protected],72
female,[email protected],22
male,[email protected],44
male,[email protected],42
female,[email protected],71
female,[email protected],32
female,[email protected],63
male,[email protected],58
female,[email protected],33
male,[email protected],38
male,[email protected],47
female,[email protected],43
female,[email protected],50
female,[email protected],61
female,[email protected],73
female,[email protected],37
female,[email protected],56
female,[email protected],34
female,[email protected],62
female,[email protected],27
female,[email protected],68
female,[email protected],40
male,[email protected],36
female,[email protected],65
male,[email protected],49
male,[email protected],30
male,[email protected],30
female,[email protected],42
male,[email protected],24
male,[email protected],25
female,[email protected],43
male,[email protected],51
male,[email protected],42
female,[email protected],54
male,[email protected],47
male,[email protected],33
female,[email protected],51
female,[email protected],35
male,[email protected],47
male,[email protected],57
female,[email protected],47
female,[email protected],52
female,[email protected],44
male,[email protected],62
male,[email protected],72
male,[email protected],76
male,[email protected],54
male,[email protected],60
male,[email protected],47
female,[email protected],42
female,[email protected],67
male,[email protected],50
female,[email protected],29
female,[email protected],42
male,[email protected],53
female,[email protected],54
male,[email protected],65
male,[email protected],36
female,[email protected],72
male,[email protected],27
male,[email protected],70
male,[email protected],73
male,[email protected],55
female,[email protected],52
female,[email protected],74
male,[email protected],24
male,[email protected],50
male,[email protected],34
female,[email protected],24
female,[email protected],61
male,[email protected],54
female,[email protected],33
female,[email protected],53
female,[email protected],55
female,[email protected],38
male,[email protected],40
female,[email protected],70
male,[email protected],22
male,[email protected],26
female,[email protected],45
female,[email protected],49
female,[email protected],31
male,[email protected],26
female,[email protected],39
male,[email protected],71
female,[email protected],31
female,[email protected],43
male,[email protected],54
male,[email protected],52
male,[email protected],60
female,[email protected],25
male,[email protected],24
male,[email protected],62
male,[email protected],39
female,[email protected],60
male,[email protected],53
male,[email protected],70
male,[email protected],29
male,[email protected],40
female,[email protected],25
female,[email protected],72
female,[email protected],73
male,[email protected],33
male,[email protected],73
female,[email protected],23
female,[email protected],56
female,[email protected],70
female,[email protected],50
female,[email protected],36
female,[email protected],65
male,[email protected],32
male,[email protected],47
male,[email protected],71
male,[email protected],32
male,[email protected],39
male,[email protected],44
male,[email protected],74
male,[email protected],48
male,[email protected],63
male,[email protected],68
male,[email protected],27
female,[email protected],69
female,[email protected],51
male,[email protected],41
male,[email protected],56
male,[email protected],56
female,[email protected],39
female,[email protected],69
male,[email protected],51
female,[email protected],47
female,[email protected],60
male,[email protected],40
female,[email protected],32
female,[email protected],72
female,[email protected],23
male,[email protected],65
male,[email protected],66
male,[email protected],64
female,[email protected],22
male,[email protected],64
female,[email protected],39
male,[email protected],40
male,[email protected],42
female,[email protected],75
female,[email protected],71
female,[email protected],71
male,[email protected],48
male,[email protected],44
female,[email protected],62
female,[email protected],50
female,[email protected],70
male,[email protected],42
female,[email protected],32
female,[email protected],43
male,[email protected],37
male,[email protected],41
male,[email protected],39
female,[email protected],48
female,[email protected],33
female,[email protected],59
male,[email protected],64
female,[email protected],50
female,[email protected],30
female,[email protected],50
male,[email protected],30
female,[email protected],33
male,[email protected],26
female,[email protected],23
male,[email protected],46
female,[email protected],52
male,[email protected],69
female,[email protected],28
female,[email protected],23
male,[email protected],60
male,[email protected],60
female,[email protected],35
male,[email protected],52
male,[email protected],40
male,[email protected],40
female,[email protected],58
male,[email protected],24
male,[email protected],55
male,[email protected],48
female,[email protected],35
male,[email protected],34
female,[email protected],25
male,[email protected],31
male,[email protected],52
male,[email protected],34
female,[email protected],40
male,[email protected],25
female,[email protected],41
male,[email protected],64
male,[email protected],36
female,[email protected],46
male,[email protected],54
male,[email protected],53
male,[email protected],65
female,[email protected],41
male,[email protected],54
female,[email protected],69
female,[email protected],65
male,[email protected],38
female,[email protected],44
female,[email protected],75
female,[email protected],74
female,[email protected],33
female,[email protected],61
female,[email protected],39
male,[email protected],24
male,[email protected],74
male,[email protected],50
male,[email protected],58
female,[email protected],31
male,[email protected],41
female,[email protected],68
male,[email protected],49
male,[email protected],57
male,[email protected],55
female,[email protected],54
male,[email protected],73
female,[email protected],25
male,[email protected],75
female,[email protected],59
female,[email protected],65
male,[email protected],70
female,[email protected],60
male,[email protected],74
male,[email protected],72
male,[email protected],41
male,[email protected],58
female,[email protected],48