Question

为什么我的代码会直接跳到else语句？如果询问，它会返回正确输入的值。但无法弄清楚为什么它只是跳到“错误！”而不是进入相关的计算器。这是我的代码：

package easy2;
import java.util.Scanner;
public class Calculator {

public static void main(String[] args) {

    float force, mass, acc;
    String answer = null;
    Scanner in = new Scanner(System.in);

    System.out.println("Force = Mass x Acceleration Calculator");

    System.out.println("Please state which variable you wish to work out: force, mass or acceleration");
    answer = in.nextLine();

    if(answer == "force"){      
        System.out.println("What is your mass in killograms?");
        mass = in.nextFloat();
        System.out.println("What is your acceleration in meters per second?");
        acc = in.nextFloat();

        force = mass * acc;

        System.out.println("The force of this equation in Netwon Meters is " + force);
        }
    else if(answer == "mass") {
            System.out.println("What is your force in Newton Meters?");
            force = in.nextFloat();
            System.out.println("What is your acceleration in meters per second?");
            acc = in.nextFloat();

            mass = force / acc;

            System.out.println("The mass of this equation is equal to " + mass + "kg");
    }
    else if(answer == "acceleration"){

        System.out.println("What is your force in Newton Meters?");
        force = in.nextFloat();
        System.out.println("What is your mass in killograms?");
        mass = in.nextFloat();

        acc = force / mass;

        System.out.println("The acceleration of this equation equals " + acc + "m/s");

    }
    else{System.out.println("ERROR!");
    }
}

}

Answer 1

尝试使用myString.equals("myOtherString")。你错误地进行了字符串比较。

Java中的

==是比较对象的相等性，而不是它们的值。

我无数次犯了同样的错误。

为什么我的代码直接跳到else语句？

1 个答案: