java - 如何更改使用许多 if 语句按名称选择类的代码？

Question

我正在开发一个程序来模拟 RLC 电路。该程序根据电路类型和源类型(RLC、LC、RC、正弦波、DC、方波...)进行一些特定计算，随后将其添加到图表中。

下面的代码按照我需要的方式工作，但是我的老师告诉我，如果我为每个案例创建一个单独的类会更好，因为太多的 if 语句不好。

if(scheme == "RLC"){
        beta = R / (2*L);
        omega0Square = 1/ (L*C);

        //Resonant
        if (omega * omega == omega0Square
                && beta >= Math.sqrt(omega0Square) / Math.sqrt(2)){

            chargeAmp = U0 / (L*2*beta*Math.sqrt(omega0Square - beta*beta));
            fi = Math.atan(Math.sqrt(omega0Square-2*beta*beta)/beta);   
        }

        //Non-resonant
        else{
            omegasDifference = (omega0Square - omega * omega);
            fi = Math.atan(2 * beta * omega / omegasDifference);
            chargeAmp = U0/(L*Math.sqrt(omegasDifference * omegasDifference
                        + 4 * beta * beta * omega * omega));
        }

        intensity = chargeAmp*omega* Math.cos(omega*time-fi);
        rU = R * intensity;
        cQ = chargeAmp*Math.sin(omega*time-fi);
        lE = L*intensity*intensity/2;
    }
    if(scheme == "LC"){

    }
    if(scheme == "RC"){

    }
    if(scheme == "R"){

    }
    if(scheme == "L"){

    }
    if(scheme == "C"){

    }
    if(scheme == "Non"){

    }

如果我为每种情况创建一个类，我以后如何管理它们，并在不使用 if 语句的情况下调用它们？我想到了这样的事情:

String name;
name variable = new name();

这可能吗？或者有更好的办法吗？

Answer 1

使用接口(interface)和 factory pattern

创建一个类来保存值(R、L、C)

public class RLCHolder {
    double rValue;
    double lValue;
    double cValue;
    //Setter and Getters
}

创建界面

public interface CircuitCalculator {
    public double calculate(RLCHolder rlcHolder);
}

现在实现接口(interface)

public class RLCCircuitCalculator implements CircuitCalculator {

    @Override
    public double calculate(RLCHolder rlcHolder) {
        // Do you Math and Return
        return 0;
    }

}

像这样添加其他电路的实现，例如。

LCCircuitCalculator 、 RCCircuitCalculator 等

现在创建工厂方法并调用计算方法

public class Calculator {

    // factory method
    public static CircuitCalculator getCircuitCalculator(String circuitName){
        CircuitCalculator circuitCalculator = null;
        if (circuitName.equals("RLC")){
            circuitCalculator =  new RLCCircuitCalculator(); // You can cache if you dont maintain state
        }else if (circuitName.equals("LC")){
            // return LC object
        }//add your implementation..
        return circuitCalculator;
    }


    public static void main(String args[]){
        RLCHolder rlcHolder = new RLCHolder();
        double result = Calculator.getCircuitCalculator("RLC").calculate(rlcHolder);
    }

}