Question

我编写了一个简单的命令行程序，用于确定通过给定接口传输大文件需要多长时间。我不明白为什么，但它总是产生这样的输出：无限秒或无限分钟传输10.0千兆字节/10240.0兆字节。

我不明白为什么它会给我输出。

import java.util.Scanner;

public class TransferTime {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        double speed = 0;
        double gigabytes = 10;
        System.out.println("This will help you find out how long it will take to transfer a file");
        System.out.println();

        System.out.println("How many gigabytes do you want to transfer?");
        gigabytes = input.nextDouble();

        System.out.println("Enter 2 for USB 2, 3 for USB 3, f for FireWire 800 or t for Thunderbolt");
        String connection = input.next();
        System.out.println();
        if (connection == "2") {
            speed = 480;

        } else if (connection == "f")
            speed = 800;

        else if (connection == "3") {
            speed = 625;
        } else if (connection == "f") {
            speed = 100;
        } else if (connection == "t") {
            speed = 1280;
        }

        double megabytes = gigabytes * 1024;
        double seconds = megabytes / speed;
        double minutes = seconds / 60;

        System.out.println("It will take " + seconds + " seconds or " + minutes
                + " minutes to transfer " + gigabytes + " gigabytes/"
                + megabytes + " megabytes");
        input.close();

    }
}

Answer 1

除以0会给你无穷大。你除以0是因为速度保持为0，因为所有条件都是假的（提示 - 不要将字符串与==进行比较）。

为什么输出总是无穷大？

1 个答案: