大话设计模式笔记 简单工厂模式

书上原版的是C#代码 

我比较熟悉java，写的是java代码。

package sampleFactory;

public class Operation {
    protected double _numberA = 0;
    protected double _numberB = 0;
    protected double result = 0;

    public double GetResult() {

        return result;
    }
}

package sampleFactory;

public class OperationAdd extends Operation {

    @Override
    public double GetResult() {
        result=_numberA+_numberB;
        return result;
    }
    
}

package sampleFactory;

public class OperationFactory {

    public static Operation createOperate(String operate) {
        Operation operation=null;
        switch (operate) {
        case "+":
            operation=new OperationAdd();
            break;

        }
        return operation;
        
    }
}

package sampleFactory;

public class Test {

    public static void main(String[] args) {
        Operation oper;
        oper=OperationFactory.createOperate("+");
        oper._numberA=1;
        oper._numberB=2;
        double result=oper.GetResult();
        System.out.println(result);
    }
}

uml图