如何在 Java 中解决其他"Syntax error on token " " "？

Question

我是新来的，但让我们直接进入问题：当我为一个类项目计算器编写以下代码时，我遇到了一个"标记错误"。这是完整的错误消息：

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
Syntax error on token "else", delete this token
at calculatorApplet.main(calculatorApplet.java:42)

我写了这个代码：

import java.util.Scanner;
import javax.swing.JOptionPane;
public class calculatorApplet
{
    Scanner sc = new Scanner(System.in);
    public static void main(String[] args)
    {
        JOptionPane.showMessageDialog(null, "Welcome to the Calculator!");
        String option = JOptionPane.showInputDialog(null, "Which calculator mode do you want?");
        if (option.equals("Addition"))
        {
            Double add1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your addition problem."));
            Double add2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your addition problem."));
            Double preAdd = add1+add2;
            Double Add = preAdd;
            JOptionPane.showMessageDialog(null, "The sum is " + Add + ".");
        }
        else
        {
            JOptionPane.showMessageDialog(null, "Huh?");
        }
        if (option.equals("Subtraction"))
        {
            Double sub1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your subtraction problem."));
            Double sub2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your subtraction problem."));
            Double preSub = sub1-sub2;
            Double Sub = preSub;
            JOptionPane.showMessageDialog(null, "The difference is " + Sub + ".");
        }
        else
        {
            JOptionPane.showMessageDialog(null, "Huh?");
        }
        if (option.equals("Multiplication"));
        {
            Double mult1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your multiplication problem."));
            Double mult2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your multiplication problem."));
            Double preMult = mult1*mult2;
            Double Mult = preMult;
            JOptionPane.showMessageDialog(null, "The product is " + Mult + ".");
        }
        else //Here is the error.
        {
            JOptionPane.showMessageDialog(null, "Huh?");
        } //Here ends the error.
        if (option.equals("Division"))
        {
            Double div1 = Double.parseDouble(JOptionPane.showInputDialog(null, "Okay type the first number(s) of your division problem."));
            Double div2 = Double.parseDouble(JOptionPane.showInputDialog(null, "Now type the second number(s) of your division problem."));
            Double preDiv = div1/div2;
            Double Div = preDiv;
            JOptionPane.showMessageDialog(null, "The quotient is " + Div + ".");
        }
        else
        {
            JOptionPane.showMessageDialog(null, "Huh?");
        }
        //End of if statements.
    } 
}

这就是代码，我评论了令牌错误所在的区域。也许解决方案就在我面前。我希望我的代码是一个计算器，这样你们就可以修复我的代码，使其和数学运算不冲突。谢谢，我很感激任何帮助。

Answer 1

从行末尾删除;：

if (option.equals("Multiplication"));

Answer 2

问题是if后面的分号。

语法为if (条件)表达式或块{else表达或块}

由于;是一个空表达式，这适用于if子句，而then子句中什么都不发生——在您的情况下，语法上没有else子句，因为if语句以分号结尾，后面跟着一个简单的块。然后，令牌化器检测到一个悬挂的else令牌并进行投诉。

Answer 3

在发生错误的If语句前面的末尾有一个分号。

if (option.equals("Multiplication"));

Answer 4

更改

if (option.equals("Multiplication"));

至

if (option.equals("Multiplication"))

不带分号

Answer 5

删除语句if (option.equals("Multiplication")); 末尾的分号（；）

Answer 6

更改：

if (option.equals("Multiplication"))

Answer 7

不需要；在if条件结束时

if（option.equals（"Multiplication"）

Answer 8

从if语句中删除分号

if (option.equals("Multiplication"));

应该是

if (option.equals("Multiplication"))