Question

我正在尝试传递aF变量。但是在调试时，它显示的值为0.任何想法？下面是我正在使用的代码（更新：我包含了整个代码）。

import java.util.ArrayList;
import java.util.List;

public class EOS {

//defining constants, input variables
public static final double GAS_CONSTANT = 8.3144598; //J K-1 mol-1
double criticalTemperature;
double criticalPressure;
double temperature;
double pressure;
double molecularWeight;

public EOS(double criticalTemperature, double criticalPressure, double temperature, double pressure, double molecularWeight) {
    this.criticalTemperature = criticalTemperature;
    this.criticalPressure = criticalPressure;
    this.temperature = temperature;
    this.pressure = pressure;
    this.molecularWeight = molecularWeight;
}

// calculation of A* and B* (values of "a" and "b" will be provided by subclasses)
public double aStar(double a) {
    return a * pressure / (Math.pow(GAS_CONSTANT, 2) * Math.pow(temperature, 2));
}

public double bStar(double b) {
    return b * pressure / (GAS_CONSTANT * temperature);
}

//calculation of Z Value. The idea is to form the cubic function of Z as follow:

public List<Double> calculateZ(double aStar, double bStar, double uValue, double wValue) {

    List<Double> solution = new ArrayList<>();

    double a, b, c, q, r, d;
    a = -1 - bStar + uValue * bStar;
    b = aStar + wValue * Math.pow(bStar, 2) - uValue * bStar - uValue * Math.pow(bStar, 2);
    c = - bStar * aStar - wValue * Math.pow(bStar, 2) - wValue * Math.pow(bStar, 3);


    q = (3*b-Math.pow(a, 2))/3;
    r = (2*Math.pow(a, 3)-9*a*b+27*c)/27;
    d = (Math.pow(q, 3)/27) + (Math.pow(r, 2)/4);


    if (d == 0) {
        double x1 = 2*Math.pow(-r/2, 1/3) -(a/3);
        double x2 = -2*Math.pow(-r/2, 1/3) -(a/3);
        double x3 = x2;

        double[] temp = {x1, x2, x3};

        for (int i = 0; i < temp.length; i++) {
            if (temp[i] > 0) {
                solution.add(temp[i]);
            }
        }

    } else if (d > 0) {
        double x1 = Math.pow((-r/2)+Math.pow(d, 0.5),1/3)+Math.pow((-r/2)+Math.pow(d, 0.5),1/3)-(a/3);

        solution.add(x1);

    } else {
        double theta = Math.acos((3*r/(2*q))*Math.sqrt(-3/q));

        double x1 = 2*Math.sqrt(-q/3)*Math.cos(theta/3)-(a/3);
        double x2 = 2*Math.sqrt(-q/3)*Math.cos((theta+2*Math.PI)/3)-(a/3);
        double x3 = 2*Math.sqrt(-q/3)*Math.cos((theta+4*Math.PI)/3)-(a/3);

        double[] temp = {x1, x2, x3};

        for (int i = 0; i < temp.length; i++) {
            if (temp[i] > 0) {
                solution.add(temp[i]);
            }

        }
    }
    return solution;
}
}

这里是子类

import java.util.Collections;

public class Soave extends EOS {


public Soave (double aFactor, double criticalTemperature, double criticalPressure, double temperature, double pressure, double molecularWeight) {
    super(criticalTemperature, criticalPressure, temperature, pressure, molecularWeight);
    this.aF = aFactor;
    this.fW = 0.48+1.574*aFactor-0.176*Math.pow(aFactor, 2);
}

double aF;
double uValue = 1;
double wValue = 0;
double fW;

public double reducedTemperature = temperature / criticalTemperature;


public double bValue = 0.08664*GAS_CONSTANT*criticalTemperature/criticalPressure;
public double aValue() {
    double term1 = 1 - Math.sqrt(reducedTemperature);
    double term2 = 1+fW*term1;
    double term3 = Math.pow(term2, 2.0); 
    double term4 = Math.pow(GAS_CONSTANT, 2)*Math.pow(criticalTemperature, 2.0);
    return 0.42748*term3*term4/criticalPressure;
}

public double aStarValue = aStar(aValue());
public double bStarValue = bStar(bValue);

public double gasZValue = Collections.max(calculateZ(aStarValue, bStarValue, uValue, wValue));
public double liquidZValue = Collections.min(calculateZ(aStarValue, bStarValue, uValue, wValue));

public double gasDensity = pressure * molecularWeight / (1000 * gasZValue * GAS_CONSTANT * temperature);
public double liquidDensity = pressure * molecularWeight / (1000 * liquidZValue * GAS_CONSTANT * temperature);

}

所以现在当我们为以下输入创建一个Soave实例时，我们应该为liquidDensity获取值568.77

        double p = 500000;
    double t = 318.15;
    double pC = 3019900;
    double tC = 507.9;
    double aF = 0.299;
    double mW = 86;

    Soave soave = new Soave(aF, tC, pC, t, p, mW);
    System.out.println(soave.liquidDensity);

Answer 1

这肯定是通过论证或阅读它的问题。查看传递值的代码段（最有可能传递0，读取时将其设为0非常“难”）。如果您仍然找不到错误，请在此处发布正确的代码。

Answer 2

在实际设置aF的值之前设置fW变量，因此它使用原始double的默认值为0.

为fW创建一个getter来进行计算，或者为构造函数块中的fW计算更多。

所以要么你喜欢这样：

public class Soave extends EOS {
public double aF;
double uValue = 1;
double wValue = 0;
public double fW;

public Soave (double aFactor, double criticalTemperature, double criticalPressure, double temperature, double pressure, double molecularWeight) {
    super(criticalTemperature, criticalPressure, temperature, pressure, molecularWeight);
    this.aF = aFactor;
    fW = 0.48+1.574*aF-0.176*Math.pow(aF, 2); //This will give you the proper number.
}

或者添加一个getter并直接进行计算（然后不需要类中的fW变量）。

public double getfWValue() {
 return 0.48+1.574*aF-0.176*Math.pow(aF, 2);
}

如果是这样，那么直接在你的print语句中使用它。

System.out.println(soave.getfWValue());

变量没有经过

2 个答案: