找不到符号 - 方法 calcAverageBill(java.util.ArrayList<java.lang.Double>)

Question

当我运行代码时，我收到此错误，我无法弄清楚原因。错误是"找不到符号 - 方法 calcAverageBill（java.util.ArrayList）"

该程序是用java编写的。头等舱：

import java.util.ArrayList;
public class CO2Footprint
{
private int myNumPeople, myBulbsReplaced;
private boolean myPaper, myPlastic, myGlass, myCans;
private double myGalsUsed, myElectricBill, myElectricPrice, billSum,     priceSum;
/**
 * Constructor for objects of type CO2Footprint
 * @param galsUsed anuual gasoline used
 * @param electricBill average electricity bill
 * @param electricPrice average electricity price
 * @param numPeople number of people in home
 * @param paper whether or not paper is recycled
 * @param plastic whether or not plastic is recycled
 * @param glass whether or not glass is recycled
 * @param cans whether or not cans are recycled
 * @param bulbsReplaced number of light bulbs replaced
 */
CO2Footprint(double galsUsed, double electricBill, double electricPrice, int numPeople, 
boolean paper, boolean plastic, boolean glass, boolean cans, int bulbsReplaced) {
    myNumPeople = numPeople;
    myBulbsReplaced = bulbsReplaced;
    myPaper = paper;
    myPlastic = plastic;
    myGlass = glass;
    myCans = cans;
    myGalsUsed = galsUsed;
    myElectricBill = electricBill;
    myElectricPrice = electricPrice;
}
public double calcAverageBill(ArrayList<Double> myElectricBill) {
    for(int i = 0; i < myElectricBill.size(); i++) {
       billSum += myElectricBill.get(i);
    }// **** insert code for method here ****//
    return billSum/3.0;
}
public double calcAveragePrice (ArrayList<Double> myElectricPrice)
{
    for (int i = 0; i < myElectricPrice.size(); i++) {
        priceSum += myElectricPrice.get(i);
    }// **** insert code for method here ****//
    return priceSum/3.0;
}
public double calcElectricityCO2 (double avgBill, double avgPrice)
{
    return (avgBill/avgPrice)*1.37*12;
    // **** insert code for method here ****//
}
}

二等舱：

import java.util.ArrayList;
    public class CO2FootPrintTester
    {
    public static void main(String[] args) {
    ArrayList<CO2Footprint> CO2 = new ArrayList<CO2Footprint>();
    ArrayList<Double> myElectricBill = new ArrayList<Double>(3);
    ArrayList<Double> myElectricPrice = new ArrayList<Double>(3);
    myElectricBill.add(209.60);
    myElectricBill.add(249.68);
    myElectricBill.add(222.59);
    myElectricPrice.add(209.70/2464);
    myElectricPrice.add(249.68/2948);
    myElectricPrice.add(222.59/2621);
   double avgBill = CO2.calcAverageBill(myElectricBill);
   double avgPrice = CO2.calcAveragePrice(myElectricPrice);
   double emissions = CO2.calcElectricityCO2(avgBill, avgPrice);
   //***********************************************************
   System.out.println("|             Pounds of CO2             |       Pounds of CO2       |                |");
   System.out.println("|             Emmitted from             |       Reduced from        |                |  ");
   System.out.println("| Gas   |    Electricity    |  Waste    |   Recycling  |  New Bulbs |  CO2 Footprint |");
   System.out.println("|-------|-------------------|-----------|--------------|------------|----------------|");
   System.out.print(emissions);
   //***********************************************************
}

}

Answer 1

calcAverageBill 是CO2Footprint类中定义的方法，但您尝试为 ArrayList 的实例调用它。

ArrayList<CO2Footprint> CO2 = new ArrayList<CO2Footprint>();
...
double avgBill = CO2.calcAverageBill(myElectricBill);

ArrayList没有这样的方法。

目前还不清楚CO2 ArrayList的目的是什么，因为你从不向其添加任何元素。也许您应该创建一个CO2Footprint实例而不是ArrayList<CO2Footprint>，并为该实例调用calcAverageBill。