Question

所以基本上这是一个简单的循环，应该将对象的距离加起来10秒。当我调试它时，我看到它传递了正确值的变量但是当我在我的fallDistance方法中计算后立即输入println语句时，变量“distance”的值为零，我看不出怎么可能。我在这里缺少什么？

import java.lang.Math;
import javax.swing.JOptionPane;

public class FallingDistance {

    public static void main(String[] args) {
    double distance =0;
        int count = 0;
        double distanceCalc = 0;
        int varTime = 0;
        while (varTime < 10) {
            varTime += 1;
            System.out.println(varTime);
            fallingDistance(varTime);
            distanceCalc += distance;
            JOptionPane.showMessageDialog(null, "The distance travelled is " + distanceCalc + " meters.");
        }

    }

    public static double fallingDistance(int varTime) {

        double gravity = 9.8;
        double distance = Math.pow(((1 / 2) * gravity * varTime), 2);
        System.out.println(gravity);
        return distance;
    }
}

Answer 1

在main！

中使用之前，您必须为distance指定值

public class FallingDistance {

public static void main(String[] args) {
double distance =0;
    int count = 0;
    double distanceCalc = 0;
    int varTime = 0;
    while (varTime < 10) {
        varTime += 1;
        System.out.println(varTime);
        distance = fallingDistance(varTime);
        distanceCalc += distance;
        JOptionPane.showMessageDialog(null, "The distance travelled is " + distanceCalc + " meters.");
    }

}

public static double fallingDistance(int varTime) {

    double gravity = 9.8;
    double distance = Math.pow(((double)(1 / 2) * gravity * varTime), 2);
    System.out.println(gravity);
    return distance;
}

Answer 2

请将fallingDistance(varTime)方法返回的值指定为distance。

你的while循环应改写为：

while (varTime < 10) {
    varTime += 1;
    System.out.println(varTime);
    distance = fallingDistance(varTime);
    distanceCalc += distance;
    JOptionPane.showMessageDialog(null, "The distance travelled is " + distanceCalc + " meters.");
}

此外，您的1/2将始终被评估为0（因为它被评估为整数）。 fallingDistance()方法应改写为：

public static double fallingDistance(int varTime) {

    double gravity = 9.8;
    double distance = Math.pow((0.5 * gravity * varTime), 2);
    System.out.println(gravity);
    return distance;
}

无法弄清楚为什么我在计算中得到一个空值

2 个答案: