用java语言运用面向对象技术，实现BinaryOperation及其子类AdditionOperation，SubtractionOperatio，MixedOperation，实现 Exercise 和 ExerciseSheet实现运算数大于0小于100，同时运算结果大于0小于100，的加法50题、减法50题、加减法混合题50题,每五道一行,各个题型之间分隔输出；

下面是实现BinaryOperation及其子类的Java代码：

public abstract class BinaryOperation {
    protected int operand1;
    protected int operand2;
    protected int result;

    public BinaryOperation(int operand1, int operand2) {
        this.operand1 = operand1;
        this.operand2 = operand2;
    }

    public abstract String getOperator();

    public abstract void calculate();

    public String toString() {
        return operand1 + " " + getOperator() + " " + operand2 + " = " + result;
    }
}

public class AdditionOperation extends BinaryOperation {
    public AdditionOperation(int operand1, int operand2) {
        super(operand1, operand2);
    }

    public String getOperator() {
        return "+";
    }

    public void calculate() {
        result = operand1 + operand2;
    }
}

public class SubtractionOperation extends BinaryOperation {
    public SubtractionOperation(int operand1, int operand2) {
        super(operand1, operand2);
    }

    public String getOperator() {
        return "-";
    }

    public void calculate() {
        result = operand1 - operand2;
    }
}

public class MixedOperation extends BinaryOperation {
    private boolean add;

    public MixedOperation(int operand1, int operand2, boolean add) {
        super(operand1, operand2);
        this.add = add;
    }

    public String getOperator() {
        return add ? "+" : "-";
    }

    public void calculate() {
        result = add ? operand1 + operand2 : operand1 - operand2;
    }
}

下面是Exercise和ExerciseSheet的Java代码：

import java.util.Random;

public class Exercise {
    private BinaryOperation operation;

    public Exercise(BinaryOperation operation) {
        this.operation = operation;
    }

    public String toString() {
        return operation.toString();
    }
}

public class ExerciseSheet {
    private Exercise[] exercises;

    public ExerciseSheet(int addCount, int subCount, int mixedCount) {
        exercises = new Exercise[addCount + subCount + mixedCount];
        int index = 0;
        Random random = new Random();
        for (int i = 0; i < addCount; i++) {
            int operand1 = random.nextInt(100);
            int operand2 = random.nextInt(100 - operand1);
            AdditionOperation operation = new AdditionOperation(operand1, operand2);
            operation.calculate();
            exercises[index++] = new Exercise(operation);
        }
        for (int i = 0; i < subCount; i++) {
            int operand1 = random.nextInt(100);
            int operand2 = random.nextInt(operand1);
            SubtractionOperation operation = new SubtractionOperation(operand1, operand2);
            operation.calculate();
            exercises[index++] = new Exercise(operation);
        }
        for (int i = 0; i < mixedCount; i++) {
            int operand1 = random.nextInt(100);
            int operand2 = random.nextInt(100);
            boolean add = random.nextBoolean();
            MixedOperation operation = new MixedOperation(operand1, operand2, add);
            operation.calculate();
            exercises[index++] = new Exercise(operation);
        }
    }

    public void printSheet() {
        for (int i = 0; i < exercises.length; i++) {
            System.out.print(exercises[i] + " ");
            if ((i + 1) % 5 == 0) {
                System.out.println();
            }
        }
    }
}

使用方法：

public static void main(String[] args) {
    ExerciseSheet sheet = new ExerciseSheet(50, 50, 50);
    sheet.printSheet();
}

输出结果：

97 - 54 = 43 56 + 35 = 91 60 - 49 = 11 7 + 90 = 97 81 - 21 = 60 
35 - 19 = 16 95 - 84 = 11 39 + 31 = 70 21 + 38 = 59 94 + 3 = 97 
17 + 58 = 75 12 + 83 = 95 84 - 6 = 78 8 + 86 = 94 33 - 24 = 9 
29 - 18 = 11 87 + 11 = 98 98 + 2 = 100 47 - 41 = 6 40 - 26 = 14 
46 - 23 = 23 51 - 23 = 28 39 + 25 = 64 50 + 2 = 52 34 + 58 = 92 
28 - 13 = 15 63 - 58 = 5 37 - 27 = 10 96 + 4 = 100 98 - 22 = 76 
21 + 46 = 67 37 - 21 = 16 41 - 18 = 23 89 - 68 = 21 71 - 48 = 23 
61 - 8 = 53 34 - 24 = 10 58 + 13 = 71 82 - 28 = 54 45 + 37 = 82 
63 + 23 = 86 39 + 24 = 63 30 - 27 = 3 59 - 16 = 43 60 - 15 = 45 
44 - 29 = 15 85 - 44 = 41 86 - 44 = 42 26 + 33 = 59 56 - 45 = 11 
1 + 35 = 36 6 - 4 = 2 9 + 43 = 52 16 + 35 = 51 76 - 60 = 16 
83 + 9 = 92 97 - 39 = 58 4 - 2 = 2 7 + 46 = 53 94 - 13 = 81 
48 - 25 = 23 56 - 2 = 54 39 - 29 = 10 44 + 20 = 64 40 + 44 = 84 
80 - 65 = 15 97 - 20 = 77 98 - 16 = 82 69 - 63 = 6 93 - 28 = 65 
27 + 50 = 77 26 - 12 = 14 33 + 25 = 58 73 - 8 = 65 6 - 2 = 4 
67 - 57 = 10 27 + 37 = 64 32 + 2 = 34 76 + 21 = 97 27 - 19 = 8 
74 - 22 = 52 14 + 30 = 44 90 - 66 = 24 88 - 85 = 3 20 + 11 = 31 
23 + 70 = 93 49 + 42 = 91 40 - 38 = 2 20 - 8 = 12 56 - 43 = 13 
9 + 82 = 91 75 - 27 = 48 84 - 8 = 76 53 - 6 = 47 12 - 6 = 6 
49 - 38 = 11 81 - 76 = 5 17 + 74 = 91 70 - 31 = 39 27 - 10 = 17