0
2

Delete article

Deleted articles cannot be recovered.

Draft of this article would be also deleted.

Are you sure you want to delete this article?

More than 1 year has passed since last update.

一週間で身につくJava言語の基本の解答集 ~基本編の問題①~

Posted at

こちらの記事は、下記のサイトを使用して教育を行っている際に
解答がなくて不便だなと思い、復習もかねてのお勉強で解答集を作成したものになります!

出来るだけ難しい書き方をせずに書くことを目的に記載中
https://java.sevendays-study.com/

※量が多いのでまずは基本編の問題の0日目~7日目まで

基本問題(1):最も基本的なプログラム、演算と変数

prob1-1.(難易度:★)

    public static void main(String[] args) {
        System.out.println("田中 太郎");
    }

prob1-2.(難易度:★)

    public static void main(String[] args) {
        System.out.println("ABCDEF\nGHI");
    }

prob1-3.(難易度:★)

    public static void main(String[] args) {
        System.out.println(1 + " + " + 1 + " = " + (1 + 1));
        System.out.println(2 + " + " + 3 + " = " + (2 + 3));
    }

prob1-4(難易度:★)

    public static void main(String[] args) {
        int num1 = 1;
        int num2 = 2;
        int num3 = 3;

        int sum = num1 + num2 + num3;

        System.out.println(num1 + " + " + num2 + " + " + num3 + " = " + sum);
    }

prob2-1.(難易度:★)

    public static void main(String[] args) {
        int a = 5, b = 3;
        System.out.println("a = " + a);
        System.out.println("b = " + b);
        System.out.println("a + b = " + (a + b));
        System.out.println("a - b = " + (a - b));
        System.out.println("a * b = " + (a * b));
        System.out.println("a / b = " + (a / b));
        System.out.println("a % b = " + (a % b));
    }

prob2-2.(難易度:★★)

    public static void main(String[] args) {
        int a = 1, b = 2, c = 3, d = 4, e = 5;
        a += 2;
        b -= 1;
        c *= 3;
        d /= 2;
        e %= 2;
        System.out.println("a = " + a);
        System.out.println("b = " + b);
        System.out.println("c = " + c);
        System.out.println("d = " + d);
        System.out.println("e = " + e);
    }

基本問題(2):条件分岐

prob3-1.(難易度:★)

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1;

        System.out.println("乱数: " + randomNumber);

        if (randomNumber >= 5) {
            System.out.println("5以上です");
        }
    }

prob3-2.(難易度:★)

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1;

        System.out.println("乱数: " + randomNumber);

        if (randomNumber != 1) {
            System.out.println("1ではありません");
        }
    }

prob3-3.(難易度:★)

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(100) + 1;

        System.out.println("乱数: " + randomNumber);

        if (randomNumber < 50) {
            System.out.println("50未満です");
        }
    }

prob3-4.(難易度:★)

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(100) + 1;

        System.out.println("乱数: " + randomNumber);

        if (randomNumber <= 10 || randomNumber >= 90) {
            System.out.println("10以下か90以上の値です");
        }
    }

prob3-5.(難易度:★)

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(100) + 1;

        System.out.println("乱数: " + randomNumber);

        if (randomNumber >= 20 && randomNumber < 80) {
            System.out.println("20以上80未満です");
        }
    }

prob3-6.(難易度:★)

    public static void main(String[] args) {
        int num = (int) (Math.random() * 6) + 1;
        System.out.println("数値 : " + num);

        if (num >= 3) {
            System.out.println("3以上です");
        }
    }

prob3-7.(難易度:★)

import java.util.Random;

public class Problem3_7 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(10) + 1;
        System.out.println(num);

        if (num >= 5) {
            System.out.println("5以上です");
        } else {
            System.out.println("5未満です");
        }
    }
}

prob3-8.(難易度:★)

import java.util.Random;

public class Problem3_8 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(10) + 1;
        System.out.println(num);

        if (num != 1) {
            System.out.println("1ではありません");
        } else {
            System.out.println("1です");
        }
    }
}

prob3-9.(難易度:★)

import java.util.Random;

public class Problem3_9 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(100) + 1;
        System.out.println(num);

        if (num < 50) {
            System.out.println("50未満です");
        } else {
            System.out.println("50以上です");
        }
    }
}

prob3-10.(難易度:★)

import java.util.Random;

public class Problem3_10 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(100) + 1; // 1から100までの乱数を生成
        System.out.println("数値: " + num);

        if (num <= 10 || num >= 90) {
            System.out.println("10以下か90以上の値です");
        } else {
            System.out.println("10より大きく90未満です");
        }
    }
}

prob3-11.(難易度:★)

import java.util.Random;

public class Problem3_11 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(100) + 1; // 1から100までの乱数を生成
        System.out.println("数値: " + num);

        if (num >= 20 && num < 80) {
            System.out.println("20以上80未満です");
        } else {
            System.out.println("20未満か、80以上です");
        }
    }
}

prob3-12.(難易度:★)

import java.util.Random;

public class Problem3_12 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(21) - 10; // -10から10までの乱数を生成
        System.out.println("数値: " + num);

        if (num < 0) {
            System.out.println("負の値です");
        } else if (num > 0) {
            System.out.println("正の値です");
        } else {
            System.out.println("0です");
        }
    }
}

prob3-13.(難易度:★)

import java.util.Random;

public class Problem3_13 {

    public static void main(String[] args) {
        Random random = new Random();
        int num = random.nextInt(3) + 1; // 1から3までの乱数を生成
        System.out.print("数値: " + num + " - ");

        if (num == 1) {
            System.out.println("グー");
        } else if (num == 2) {
            System.out.println("パー");
        } else {
            System.out.println("チョキ");
        }
    }
}

prob3-15.(難易度:★★)

import java.util.Random;

public class Problem3_15 {

    public static void main(String[] args) {
        Random random = new Random();
        int score = random.nextInt(100) + 1; // 1から100までの乱数を生成
        System.out.println("点数: " + score);

        if (score >= 80) {
            System.out.println("優");
        } else if (score >= 70) {
            System.out.println("良");
        } else if (score >= 60) {
            System.out.println("可");
        } else {
            System.out.println("不可");
        }
    }
}

prob3-16.(難易度:★★)

import java.util.Random;

public class Problem3_16 {

    public static void main(String[] args) {
        Random random = new Random();
        int number = random.nextInt(100) + 1; // 1から100までの乱数を生成
        System.out.println("数値: " + number);

        if (number % 2 == 0 && number % 3 == 0) {
            System.out.println("2と3の公倍数です");
        } else if (number % 2 == 0) {
            System.out.println("2の倍数です");
        } else if (number % 3 == 0) {
            System.out.println("3の倍数です");
        }
    }
}

prob3-17.(難易度:★★)

import java.util.Random;

public class Problem3_17 {

    public static void main(String[] args) {
        Random random = new Random();
        int number = random.nextInt(100) + 1; // 1から100までの乱数を生成
        System.out.println("数値: " + number);

        if (number <= 50 && number % 2 == 0) {
            System.out.println("50以下の偶数です");
        } else if (number <= 50) {
            System.out.println("50以下です");
        } else if (number % 2 == 0) {
            System.out.println("偶数です");
        }
    }
}

prob3-18.(難易度:★★)

import java.util.Random;

public class Problem3_18 {

    public static void main(String[] args) {
        Random random = new Random();
        int temperature = random.nextInt(46) - 10; // -10から35までの乱数を生成
        System.out.println("摂氏" + temperature + "度");

        if (temperature >= 30) {
            System.out.println("真夏日です");
        } else if (temperature >= 25) {
            System.out.println("夏日です");
        } else if (temperature < 0) {
            System.out.println("真冬日です");
        }
    }
}

基本問題(3):繰り返し処理

prob4-1.(難易度:★)

import java.util.Random;

public class Problem4_1 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成
        System.out.println("数: " + randomNumber);

        for (int i = 0; i < randomNumber; i++) {
            System.out.print("■");
        }
        System.out.println(); // 改行
    }
}

prob4-2.(難易度:★)

import java.util.Random;

public class Problem4_2 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成
        System.out.println("数: " + randomNumber);

        int i = 0;
        while (i < randomNumber) {
            System.out.print("■");
            i++;
        }
        System.out.println(); // 改行
    }
}

prob4-3.(難易度:★)

import java.util.Random;

public class Problem4_3 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成
        System.out.println("数: " + randomNumber);

        int i = 0;
        do {
            System.out.print("■");
            i++;
        } while (i < randomNumber);
        System.out.println(); // 改行
    }
}

prob4-4(難易度:★)

public class Problem4_4 {

    public static void main(String[] args) {
        int a = 0;
        while (a < 4) {
            System.out.println("a = " + a);
            a++;
        }
    }
}

prob4-5(難易度:★)

public class Problem4_5 {

    public static void main(String[] args) {
        for (int a = 0; a < 4; a++) {
            System.out.println("a = " + a);
        }
    }
}

prob4-6(難易度:★)

public class Problem4_6 {

    public static void main(String[] args) {
        int a = 3;
        while (a >= 0) {
            System.out.println("a = " + a);
            a--;
        }
    }
}

prob4-7(難易度:★)

public class Problem4_7 {

    public static void main(String[] args) {
        for (int a = 3; a >= 0; a--) {
            System.out.println("a = " + a);
        }
    }
}

prob4-8.(難易度:★★)

import java.util.Random;

public class Problem4_8 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber;
        
        while (true) {
            randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成
            System.out.println(randomNumber);
            if (randomNumber == 10) {
                System.out.println("終了します");
                break;
            }
        }
    }
}

prob4-9.(難易度:★★)

import java.util.Random;

public class Problem4_9 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber;
        
        while (true) {
            randomNumber = random.nextInt(100) + 1; // 1から100までの乱数を生成
            System.out.println(randomNumber);
            if (randomNumber % 10 == 0) {
                System.out.println("終了します");
                break;
            }
        }
    }
}

prob4-10.(難易度:★)

import java.util.Random;

public class Problem4_10 {

    public static void main(String[] args) {
        Random random = new Random();

        for (int i = 0; i < 5; i++) {
            int randomNumber = random.nextInt(100) + 1; // 1から100までの乱数を生成
            System.out.println(randomNumber);
        }
    }
}

prob4-11.(難易度:★★)

import java.util.Random;

public class Problem4_11 {

    public static void main(String[] args) {
        Random random = new Random();
        int maxNumber = 0;

        for (int i = 0; i < 5; i++) {
            int randomNumber = random.nextInt(100) + 1; // 1から100までの乱数を生成
            System.out.println(randomNumber);
            
            if (randomNumber > maxNumber) {
                maxNumber = randomNumber;
            }
        }

        System.out.println("最大値: " + maxNumber);
    }
}

prob4-12.(難易度:★★)

import java.util.Random;

public class Problem4_12 {

    public static void main(String[] args) {
        Random random = new Random();
        int minNumber = 101; // 最小値を初期化

        for (int i = 0; i < 5; i++) {
            int randomNumber = random.nextInt(100) + 1; // 1から100までの乱数を生成
            System.out.println(randomNumber);

            if (randomNumber < minNumber) {
                minNumber = randomNumber;
            }
        }

        System.out.println("最小値: " + minNumber);
    }
}

prob4-13.(難易度:★★)

import java.util.Random;

public class Problem4_13 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成

        if (randomNumber >= 5) {
            for (int i = 0; i < randomNumber; i++) {
                System.out.print("★");
            }
        } else {
            System.out.println("発生した数値: " + randomNumber);
        }
    }
}

prob4-14.(難易度:★★)

import java.util.Random;

public class Problem4_14 {

    public static void main(String[] args) {
        Random random = new Random();
        int randomNumber = random.nextInt(10) + 1; // 1から10までの乱数を生成

        if (randomNumber % 2 == 0) {
            for (int i = 0; i < randomNumber; i++) {
                System.out.print("★");
            }
        } else {
            for (int i = 0; i < randomNumber; i++) {
                System.out.print("☆");
            }
        }
    }
}

prob4-15.(難易度:★★)

public class Problem4_15 {

    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            System.out.print(i + " ");
            if (i % 10 == 0) {
                System.out.println(); // 10の倍数で改行
            }
        }
    }
}

prob4-16.(難易度:★)

public class Problem4_16 {

    public static void main(String[] args) {
        for (int i = 1; i <= 9; i++) {
            for (int j = 1; j <= 9; j++) {
                System.out.print(i + "×" + j + "=" + (i * j) + " ");
            }
            System.out.println(); // 改行
        }
    }
}

prob4-17.(難易度:★★)

public class Problem4_17 {

    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10; j++) {
                if (j <= i) {
                    System.out.print("■");
                } else {
                    System.out.print("□");
                }
            }
            System.out.println(); // 改行
        }
    }
}

prob4-18.(難易度:★★)

public class Problem4_18 {

    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < 10; j++) {
                if (j == i) {
                    System.out.print("□");
                } else {
                    System.out.print("■");
                }
            }
            System.out.println(); // 改行
        }
    }
}

基本問題(4):配列変数

prob5-1.(難易度:★)

import java.util.Random;

public class Problem5_1 {

    public static void main(String[] args) {
        int[] a = new int[7];
        Random random = new Random();

        for (int i = 0; i < a.length; i++) {
            a[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            System.out.print("a[" + i + "]=" + a[i] + " ");
        }
    }
}

prob5-2.(難易度:★)

public class Problem5_2 {

    public static void main(String[] args) {
        double[] d = {0.2, -5.1, 3.2, 1.8};

        for (int i = 0; i < d.length; i++) {
            System.out.print("d[" + i + "]=" + d[i] + " ");
        }
    }
}

prob5-3.(難易度:★★)

import java.util.Random;

public class Problem5_3 {

    public static void main(String[] args) {
        int[] data = new int[10];
        Random random = new Random();
        int evenCount = 0;
        int oddCount = 0;

        for (int i = 0; i < data.length; i++) {
            data[i] = random.nextInt(100) + 1; // 1から100までの乱数を代入
            System.out.print(data[i] + " ");
            if (data[i] % 2 == 0) {
                evenCount++;
            } else {
                oddCount++;
            }
        }

        System.out.println("\n奇数 : " + oddCount);
        System.out.println("偶数 : " + evenCount);
    }
}

prob5-4.(難易度:★★)

import java.util.Random;

public class Problem5_4 {

    public static void main(String[] args) {
        int[] data = new int[100];
        Random random = new Random();
        int below50Count = 0;
        int aboveOrEqual50Count = 0;

        for (int i = 0; i < data.length; i++) {
            data[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            System.out.print(data[i] + " ");
            if (data[i] >= 50) {
                aboveOrEqual50Count++;
            } else {
                below50Count++;
            }
        }

        System.out.println("\n50以上の数 : " + aboveOrEqual50Count);
        System.out.println("50未満の数 : " + below50Count);
    }
}

prob5-5.(難易度:★★)

import java.util.Random;

public class Problem5_5 {

    public static void main(String[] args) {
        int[] data = new int[10];
        Random random = new Random();
        int multipleOf3Count = 0;
        int notMultipleOf3Count = 0;

        for (int i = 0; i < data.length; i++) {
            data[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            System.out.print(data[i] + " ");
            if (data[i] % 3 == 0) {
                multipleOf3Count++;
            } else {
                notMultipleOf3Count++;
            }
        }

        System.out.println("\n3の倍数 : " + multipleOf3Count);
        System.out.println("3の倍数以外の数 : " + notMultipleOf3Count);
    }
}

prob5-6.(難易度:★★)

import java.util.Random;

public class Problem5_5 {

    public static void main(String[] args) {
        int[] data = new int[10];
        Random random = new Random();
        int multipleOf3Count = 0;
        int notMultipleOf3Count = 0;

        for (int i = 0; i < data.length; i++) {
            data[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            System.out.print(data[i] + " ");
            if (data[i] % 3 == 0) {
                multipleOf3Count++;
            } else {
                notMultipleOf3Count++;
            }
        }

        System.out.println("\n3の倍数 : " + multipleOf3Count);
        System.out.println("3の倍数以外の数 : " + notMultipleOf3Count);
    }
}

prob5-7.(難易度:★★★)

import java.util.Random;

public class Problem5_7 {

    public static void main(String[] args) {
        int[] array = new int[5];
        Random random = new Random();
        int sum = 0;
        int average;
        int greaterThanAverage = 0;
        int lessThanAverage = 0;

        for (int i = 0; i < array.length; i++) {
            array[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            System.out.print(array[i] + " ");
            sum += array[i];
        }

        average = sum / array.length;
        System.out.println("\n合計値:" + sum);
        System.out.println("平均値:" + average);

        for (int i = 0; i < array.length; i++) {
            if (array[i] > average) {
                greaterThanAverage++;
            } else if (array[i] < average) {
                lessThanAverage++;
            }
        }

        System.out.println("\n平均値より大きい数:" + greaterThanAverage);
        System.out.println("平均値より小さい数:" + lessThanAverage);
    }
}

prob5-8.(難易度:★★)

import java.util.Random;

public class Problem5_8 {

    public static void main(String[] args) {
        int[] array = new int[5];
        Random random = new Random();
        int greaterThanZero = 0;
        int lessThanZero = 0;
        int equalToZero = 0;

        for (int i = 0; i < array.length; i++) {
            array[i] = random.nextInt(21) - 10; // -10から10までの乱数を代入
            System.out.print(array[i] + " ");
            if (array[i] > 0) {
                greaterThanZero++;
            } else if (array[i] < 0) {
                lessThanZero++;
            } else {
                equalToZero++;
            }
        }

        System.out.println("\n0より大きい数:" + greaterThanZero);
        System.out.println("0より小さい数:" + lessThanZero);
        System.out.println("0の個数:" + equalToZero);
    }
}

prob5-9.(難易度:★★)

import java.util.Random;

public class Problem5_9 {

    public static void main(String[] args) {
        int[] array = new int[10];
        Random random = new Random();
        int aboveOrEqual50Count = 0;
        int below50Count = 0;

        for (int i = 0; i < array.length; i++) {
            array[i] = random.nextInt(101); // 0から100までの乱数を代入
            System.out.print(array[i] + " ");
            if (array[i] >= 50) {
                aboveOrEqual50Count++;
            } else {
                below50Count++;
            }
        }

        System.out.println("\n50以上の数:" + aboveOrEqual50Count);
        System.out.println("50未満の数:" + below50Count);
    }
}

prob5-10.(難易度:★★)

import java.util.Random;

public class Problem5_10 {

    public static void main(String[] args) {
        int[] array = new int[7];
        Random random = new Random();

        for (int i = 0; i < array.length; i++) {
            array[i] = random.nextInt(10) + 1; // 1から10までの乱数を代入
            for (int j = 0; j < array[i]; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

prob5-11.(難易度:★★)

import java.util.Random;

public class Problem5_11 {

    public static void main(String[] args) {
        int[] array = new int[5];
        Random random = new Random();

        for (int i = 0; i < array.length; i++) {
            array[i] = random.nextInt(100) + 1; // 1から100までの乱数を代入
            System.out.print(array[i] + " ");
        }

        System.out.println("\n\n0以上60未満:");
        for (int i = 0; i < array.length; i++) {
            if (array[i] >= 0 && array[i] < 60) {
                System.out.print(array[i] + " ");
            }
        }

        System.out.println("\n\n60以上80未満:");
        for (int i = 0; i < array.length; i++) {
            if (array[i] >= 60 && array[i] < 80) {
                System.out.print(array[i] + " ");
            }
        }

        System.out.println("\n\n80以上:");
        for (int i = 0; i < array.length; i++) {
            if (array[i] >= 80) {
                System.out.print(array[i] + " ");
            }
        }
    }
}

prob5-12.(難易度:★)

import java.util.Random;

public class Problem5_12 {

    public static void main(String[] args) {
        int[][]

 matrix = new int[3][3];
        Random random = new Random();

        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                matrix[i][j] = random.nextInt(10); // 0から9までの乱数を代入
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

prob5-13.(難易度:★★)

import java.util.Random;

public class Problem5_13 {

    public static void main(String[] args) {
        int[][] matrix = new int[3][3];
        Random random = new Random();
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;

        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                matrix[i][j] = random.nextInt(10); // 0から9までの乱数を代入
                System.out.print(matrix[i][j] + " ");
                if (matrix[i][j] > max) {
                    max = matrix[i][j];
                }
                if (matrix[i][j] < min) {
                    min = matrix[i][j];
                }
            }
            System.out.println();
        }

        System.out.println("\n最大値:" + max);
        System.out.println("最小値:" + min);
    }
}

基本問題(5):クラスとオブジェクト

prob6-1.(難易度★)

package problem6;

public class Problem6_1 {

    public static void main(String[] args) {
        Minmax m = new Minmax();
        int a = 4, b = 2, c = 6;
        System.out.println(a + "と" + b + "と" + c + "のうち、最大のものは" + m.max(a, b, c));
        System.out.println(a + "と" + b + "と" + c + "のうち、最小のものは" + m.min(a, b, c));
    }
}
package problem6;

public class Minmax {
    // 最大値の取得
    public int max(int n1, int n2, int n3) {
        int max = n1;
        if (n2 > max) {
            max = n2;
        }
        if (n3 > max) {
            max = n3;
        }
        return max;
    }
    // 最小値の取得
    public int min(int n1, int n2, int n3) {
        int min = n1;
        if (n2 < min) {
            min = n2;
        }
        if (n3 < min) {
            min = n3;
        }
        return min;
    }
}

prob6-2.(難易度★)

package problem6;

public class Problem6_2 {

    public static void main(String[] args) {
        Calc c = new Calc();
        double a = 4.0, b = 2.0;
        System.out.println(a + " + " + b + " = " + c.add(a, b));
        System.out.println(a + " - " + b + " = " + c.sub(a, b));
        System.out.println(a + " * " + b + " = " + c.mul(a, b));
        System.out.println(a + " / " + b + " = " + c.div(a, b));
    }
}
package problem6;

public class Calc {
    // 加算
    double add(double a, double b) {
        return a + b;
    }
    // 減算
    double sub(double a, double b) {
        return a - b;
    }
    // 乗算
    double mul(double a, double b) {
        return a * b;
    }
    // 除算
    double div(double a, double b) {
        if (b != 0) {
            return a / b;
        } else {
            System.out.println("0で割ることはできません。");
            return 0;
        }
    }
}

prob6-3.(難易度★)

package problem6;

public class Problem6_3 {

    public static void main(String[] args) {
        Circle c = new Circle();
        // 円の半径を設定
        c.r = 4.0;
        System.out.println("半径" + c.r + "の円の円周の長さは" + c.circumference());
        System.out.println("半径" + c.r + "の円の面積の長さは" + c.area());
    }
}
package problem6;

public class Circle {
    // 半径
    public double r;
    // 円周の長さを求める
    public double circumference() {
        return 2 * 3.14 * r;
    }
    // 面積を求める
    public double area() {
        return 3.14 * r * r;
    }
}

基本問題(6):アクセス指定子とカプセル化

prob7-1.(難易度★)

package problem7;

public class Data {
    // メンバ変数number
    private int number = 0;
    // メンバ変数comment
    private String comment = "";

    // numberのセッターメソッド
    public void setNumber(int number) {
        this.number = number;
    }

    // numberのゲッターメソッド
    public int getNumber() {
        return number;
    }

    // commentのセッターメソッド
    public void setComment(String comment) {
        this.comment = comment;
    }

    // commentのゲッターメソッド
    public String getComment() {
        return comment;
    }
}

prob7-2.(難易度★)

package problem7;

public class TwoStrings {
    // 一つ目の文字列
    private String string1;
    // 二つ目の文字列
    private String string2;

    // 一つ目の文字列を設定
    public void setString1(String string1) {
        this.string1 = string1;
    }

    // 二つ目の文字列を設定
    public void setString2(String string2) {
        this.string2 = string2;
    }

    // 一つ目の文字列を取得
    public String getString1() {
        return string1;
    }

    // 二つ目の文字列を取得
    public String getString2() {
        return string2;
    }

    // 二つの文字列を合成して返すメソッド
    public String getConnectedString() {
        return string1 + string2;
    }
}

prob7-3.(難易度★)

package problem7;

public class Calculation {
    // フィールド
    private int number1;
    private int number2;

    // number1のセッターメソッド
    public void setNumber1(int number1) {
        this.number1 = number1;
    }

    // number2のセッターメソッド
    public void setNumber2(int number2) {
        this.number2 = number2;
    }

    // number1のゲッターメソッド
    public int getNumber1() {
        return number1;
    }

    // number2のゲッターメソッド
    public int getNumber2() {
        return number2;
    }

    // 二つの数の和を計算するメソッド
    public int add() {
        return number1 + number2;
    }

    // 二つの数の差を計算するメソッド
    public int sub() {
        return number1 - number2;
    }
}
0
2
0

Register as a new user and use Qiita more conveniently

  1. You get articles that match your needs
  2. You can efficiently read back useful information
  3. You can use dark theme
What you can do with signing up
0
2

Delete article

Deleted articles cannot be recovered.

Draft of this article would be also deleted.

Are you sure you want to delete this article?