Question

我需要创建一个数组列表来保存用户输入的电阻值。然后我需要询问用户用哪种方法计算他的答案，然后返回答案。 do while循环需要不断询问电阻值，直到用户输入数字零。计算必须从抵抗阶段拉到主要阶段。

的的 ** CLASS 的 * **

import java.util.ArrayList;    

public class Resistance {

    /**
     * Holds an object type.
     */
    public int userChoice;

    ArrayList<Double> resistor = new ArrayList<Double>();

    /**
     *Chooses which process follows next.
     *@return circuitType
     */
    public final double calculateResistance() {
        if (userChoice == 1) {
            return calculateSeriesResistance();
        } else {
            return calculaParallelResistance();
        }
    }
    /**Returns object of parallel circuit.
     *
     * @return 1 / runningResistance.
     */

    public double calculaParallelResistance() {
        double runningResistance = 0;

        for (int index = 0; index < resistor.lenght; ++index) {
            runningResistance = runningResistance
                    + +1 / resistor.lenght;
        }
        return 1 / runningResistance;
        }

    /**Returns object of series circuit.
     *
     * @return runningResistance.
     */
    private double calculateSeriesResistance() {
        double runningResistance = 0;    
        for (int index = 0; index < resistor.length; ++index) {
            runningResistance = runningResistance + resistor[index];
    }    
        return runningResistance;
    }
}

的的 ** * MAIN 的 * < / EM> ** * ****

import java.text.DecimalFormat; import java.util.Scanner; public class Main { /** * Makes a Constant. */ public final static int DONE = 0; /** * Makes a Constant. */ public static final int USER_CHOICE_SERIES = 1; /** * Makes a Constant. */ public static final int USER_CHOICE_PARALLEL = 2; public static void main(final String[] args) { // TODO Auto-generated method stub DecimalFormat f = new DecimalFormat("##.00"); Resistance myRes = new Resistance(); Scanner keyboard = new Scanner(System.in); //Display Purpose System.out.println("\nThis program will calculate " + "the resistance of a Parallel or Series " + "Circuit\n"); //Display instructions System.out.println("Please enter the value of your " + "resistors separately, when done press 0 (zero)"); int n = 0; do { System.out.println("Enter Resistor #" + ++n); myRes.resistor.add(keyboard.nextDouble()); } while (myRes.resistor > 0); // Ask Which Method To Use, do { System.out.println("\nEnter 1 to calculate " + "a Series Circuit " + "or 2 for a Parallel Circuit"); myRes.userChoice = keyboard.nextInt(); // Ask user again in case he enters something else } while (myRes.userChoice != USER_CHOICE_PARALLEL && myRes.userChoice != USER_CHOICE_SERIES); //Output the total resistance System.out.printf("\nThe Total Resistance is " + f.format(myRes.calculateResistance())); } }

Answer 1

如上所述，你的代码几乎没有，我们一步一步地分解它。

首先，ArrayList没有名为length的字段，你想要使用size（）。

接下来，计算并联电阻的方法是错误的。您没有迭代电阻，而是使用多个电阻来计算。正确的公式是：

1 / Rtotal = 1 / R1 + 1 / R1 + 1 / R3 + ...

将您的代码更改为：

 public double calculaParallelResistance() {
    double runningResistance = 0;

    //use size() instead of length, which doesn't exist in ArrayList
    for (int index = 0; index < resistor.size(); index++) {
        //also, iterate over each resistor's value, and to get it, 
        //use...err, get() method :)
        runningResistance +=  (1 / resistor.get(index));
    }
    return 1 / runningResistance;
}

您的方法calculateSeriesResistance（）也有一个问题：您无法使用数组表示法访问对象，如抵抗[index]。使用get（）方法，所以正确的代码是：

private double calculateSeriesResistance() {
    double runningResistance = 0;
    for (int index = 0; index < resistor.size(); index++) {
        runningResistance += resistor.get(index);
    }
    return runningResistance;
}

现在，以主要方法。您的第一个'do'循环是检查ArrayList中的电阻数，而不是用户输入的0值。您可以使用while循环，并在输入0时中断：

//holds current resistor's value
Double val;

while(true) {
    System.out.println("Enter Resistor #" + ++n);
    val = keyboard.nextDouble();

    //only add if higher than 0
    if (val > 0.0) {
        myRes.resistor.add(val);
    }
    //0 entered, so finish the loop
    else break;
}

Arraylist，while while循环并调用方法

1 个答案: