参见英文答案 > Unknown error relating to syntax of tokens                                    1个
我收到一个我不明白的错误：

此行有多个标记
     – 令牌上的语法错误,放错位置
     结构体)
     – 令牌上的语法错误,删除这些令牌

以下是我的类代码,错误发生在第8行(标记)：

import java.util.*;

public class stringCalculator {
    String operator_array[] = {"+", "-", "/", "*", "(", ")"};
    Queue<Integer> outputQueue = new LinkedList<Integer>();
    Stack <Object> operatorStack = new Stack<Object>();
    Hashtable<String, Integer> precendece = new Hashtable<String, Integer>();
    precedence.put("+", 2); <=========== This is where the error occurs

    public void printTokenList(String [] expression, int length)
    {
        for(int i = 0; i < length; i++){
            System.out.println(expression[i]);
        }
    }

    public void checkInput(String [] expression, int length)
    {
        System.out.println(expression);
        for(int i = 0; i < length; i ++){
                if(checkIfNumber(expression[i])){
                int new_expression = Integer.parseInt(expression[i]);
                outputQueue.add(new_expression);
            }
            else if(expression[i].equals("+") || expression[i].equals("-") || expression[i].equals("/") || expression[i].equals("*")){
                for(int j = 0; j < 6; j++){
                    if(expression[i].equals(operator_array[j])){
                    operatorStack.push(expression[i]);
                    }
                }
            }
        }
    }

    public static boolean checkIfNumber(String expression)  
    {  
      try  
      {  
          double number = Double.parseDouble(expression);  
      }  
      catch(NumberFormatException nfe)  
      {  
        return false;
      }  
      return true;  
    }

    public void checkPrecedence()
    {

    }
}

解决方法:

语句precedence.put(“”,2);必须在方法或块内.

例如,您可以将其放在构造函数中

public stringCalculator() {
    precedence.put("+", 2);
}

根据Java Naming Conventions,与你所遇到的问题无关,类需要以大写字母开头