第4章

コード04-01

Main.java

public class Main {
  public static void main(String[] args) {
    int sansu = 20;
    int kokugo = 30;
    int rika = 40;
    int eigo = 50;
    int syakai = 80;

    int sum = sansu + kokugo + rika + syakai + eigo;

    int avg = sum / 5;
    System.out.println("合計点:" + sum);
    System.out.println("平均点:" + avg);
  }
}

コード04-02

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores;
    scores = new int[5];
  }
}

コード04-03

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = new int[5];
  }
}

コード04-04

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = new int[5];
    int num = scores.length;
    System.out.println("要素の数: " + num);
  }
}

コード04-05

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores;
    scores = new int[5];
    scores[1] = 30;
    System.out.println(scores[1]);
  }
}

コード04-06

Main.java

public class Main {
  public static void main(String[] args) {
    int x;
    System.out.println(x);
  }
}

コード04-07

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = new int[5];
    System.out.println(scores[0]);
  }
}

コード04-08

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    int sum = scores[1] + scores[2] + scores[3] + scores[4] + scores[5];
    int avg = sum / scores.length;
    System.out.println("合計点:" + sum);
    System.out.println("平均点:" + avg);
  }
}

コード04-09

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    for (int i = 0; i < scores.length; i++) {
      System.out.println(scores[i]);
    }
  }
}

コード04-10

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    int sum = 0;
    for (int i = 0; i < scores.length; i++) {
      sum += scores[i];
    }
    int avg = sum / scores.length;
    System.out.println("合計点:" + sum);
    System.out.println("平均点:" + avg);
  }
}

コード04-11

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    int count = 0;
    for (int i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count++;
      }
    }
    System.out.println("50点以上の科目の数は:" + count);
  }
}

コード04-12

Main.java

public class Main {
  public static void main(String[] args) {
    int[] seq = new int[10];

    // 塩基配列をランダムに生成
    for (int i = 0; i < seq.length; i++) {
      seq[i] = new java.util.Random().nextInt(4);
    }

    // 生成した塩基配列の記号を表示
    for (int i = 0; i < seq.length; i++) {
      switch (seq[i]) {
        case 0 -> {
          System.out.print("A ");
        }
        case 1 -> {
          System.out.print("T ");
        }
        case 2 -> {
          System.out.print("G ");
        }
        case 3 -> {
          System.out.print("C ");
        }
      }
    }
  }
}

コード04-13

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    for (int i = 0; i < scores.length; i++) {
      System.out.println(scores[i]);
    }
  }
}

コード04-14

Main.java

public class Main {
  public static void main(String[] args) {
    int[] scores = {20, 30, 40, 50, 80};
    for (int value : scores) {
      System.out.println(value);
    }
  }
}

コード04-15

Main.java

public class Main {
  public static void main(String[] args) {
    int[] arrayA = {1, 2, 3};
    int[] arrayB;
    arrayB = arrayA;
    arrayB[0] = 100;
    System.out.println(arrayA[0]);
  }
}

コード04-16

Main.java

public class Main {
  public static void main(String[] args) {
    boolean judge = true;
    if (judge == true) {
      int[] array = {1, 2, 3};
    }
  }
}

コード04-17

Main.java

public class Main {
  public static void main(String[] args) {
    int[] array = {1, 2, 3};
    array = null;
    array[0] = 10;
  }
}

コード04-18

Main.java

public class Main {
  public static void main(String[] args) {
    int[][] scores = new int[2][3];
    scores[0][0] = 40;
    scores[0][1] = 50;
    scores[0][2] = 60;
    scores[1][0] = 80;
    scores[1][1] = 60;
    scores[1][2] = 70;
    System.out.println(scores[1][1]);
  }
}

コード04-19

Main.java

public class Main {
  public static void main(String[] args) {
    int[][] scores = {{40, 50, 60}, {80, 60, 70}};
    System.out.println(scores.length);
    System.out.println(scores[0].length);
  }
}