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public abstract class Operation {
    private double numberA;
    private double numberB;

    public double getNumberA() {
        return numberA;
    }

    public void setNumberA(double numberA) {
        this.numberA = numberA;
    }

    public double getNumberB() {
        return numberB;
    }

    public void setNumberB(double numberB) {
        this.numberB = numberB;
    }

    public abstract double getResult();
}

class OperationAdd extends Operation {

    @Override
    public double getResult() {
        return this.getNumberA()+this.getNumberB();
    }
}

class  OperationSub extends Operation {
    @Override
    public double getResult() {
        return this.getNumberA() - this.getNumberB();
    }
}

class OperationMul extends Operation {
    @Override
    public double getResult() {
        return this.getNumberA() * this.getNumberB();
    }
}

class OperationDiv extends Operation {
    @Override
    public double getResult() {
        if (this.getNumberB() == 0) {
            throw new RuntimeException("除数不能为0");
        }
        return this.getNumberA() / this.getNumberB();
    }
}

public class OperationFactory {
    public static Operation createOperation(String operate) {
        Operation operation = null;
        switch (operate) {
            case "+":
                operation = new OperationAdd();
                break;
            case "-" :
                operation = new OperationSub();
                break;
            case "*":
                operation = new OperationMul();
                break;
            case "/":
                operation = new OperationDiv();
                break;
            default:
                break;
        }
        return operation;
    }
}

public class OperationMain {
    public static void main(String[] args) {
        double numberA = 10;
        double numberB = 0;
        Operation operation = OperationFactory.createOperation("/");
        operation.setNumberA(numberA);
        operation.setNumberB(numberB);
        System.out.println(operation.getResult());
    }
}