有办法解决或修复我的Revel的Exercise20_23.java代码吗？

Question

我试图让Exercise20_23.java工作，但它不起作用。

我试过这个；

import java.util.*;

public class Exercise20_23 {
   public static void main(String[] args) {
      Scanner scanner = new Scanner(System.in);
      System.out.print("Enter an expression: ");
      String expression = scanner.nextLine();
      
      try {
         System.out.println(expression + " = " + evaluateExpression(expression));
      }
      catch (Exception ex) {
         System.out.println("Wrong expression: " + expression);
      }
   }
     
   /** Evaluate an expression */
   public static int evaluateExpression(String expression) {
      // Create operandStack to store operands
      Stack<Integer> operandStack = new Stack<>();
    
      // Create operatorStack to store operators
      Stack<Character> operatorStack = new Stack<>();
    
      // Insert blanks around (, ), +, -, /, *, ^, and %
      expression = insertBlanks(expression);
   
      // Extract operands and operators
      String[] tokens = expression.split(" ");
   
      // Phase 1: Scan tokens
      for (String token: tokens) {
         if (token.length() == 0) // Blank space
            continue; // Back to the for loop to extract the next token
         else if (token.charAt(0) == '+' || token.charAt(0) == '-') {
            // Process all +, -, *, /, ^. % in the top of the operator stack 
            while (!operatorStack.isEmpty() &&
               (operatorStack.peek() == '+' || 
                operatorStack.peek() == '-' ||
                operatorStack.peek() == '*' ||
                operatorStack.peek() == '/' ||
                operatorStack.peek() == '^' ||
                operatorStack.peek() == '%')) {
               processAnOperator(operandStack, operatorStack);
            }
         
            // Push the + or - operator into the operator stack
            operatorStack.push(token.charAt(0));
         }
         else if (token.charAt(0) == '*' || token.charAt(0) == '/' || token.charAt(0) == '%') {
            // Process all *, /, % in the top of the operator stack 
            while (!operatorStack.isEmpty() &&
               (operatorStack.peek() == '*' ||
                operatorStack.peek() == '/' ||
                operatorStack.peek() == '%' )) {
               processAnOperator(operandStack, operatorStack);
            }
         
            // Push the *, /, or % operator into the operator stack
            operatorStack.push(token.charAt(0));
         }
         else if (token.charAt(0) == '^') {
            // Process all ^ in the top of the operator stack 
            while (!operatorStack.isEmpty() &&
               (operatorStack.peek() == '^')) {
               processAnOperator(operandStack, operatorStack);
            }
         
            // Push the ^ operator into the operator stack
            operatorStack.push(token.charAt(0));
         }
         else if (token.trim().charAt(0) == '(') {
            operatorStack.push('('); // Push '(' to stack
         }
         else if (token.trim().charAt(0) == ')') {
            // Process all the operators in the stack until seeing '('
            while (operatorStack.peek() != '(') {
               processAnOperator(operandStack, operatorStack);
            }
            
            operatorStack.pop(); // Pop the '(' symbol from the stack
         }
         else { // An operand scanned
            // Push an operand to the stack
            operandStack.push(Integer.valueOf(token));
         }
      }
   
      // Phase 2: Process all the remaining operators in the stack 
      while (!operatorStack.isEmpty()) {
         processAnOperator(operandStack, operatorStack);
      }
   
      // Return the result
      return operandStack.pop();
   }

   /** Process one operator: Take an operator from operatorStack and
    *  apply it on the operands in the operandStack */
   public static void processAnOperator(Stack<Integer> operandStack, Stack<Character> operatorStack) {
      char op = operatorStack.pop();
      int op1 = operandStack.pop();
      int op2 = operandStack.pop();
      if (op == '+') 
         operandStack.push(op2 + op1);
      else if (op == '-') 
         operandStack.push(op2 - op1);
      else if (op == '*') 
         operandStack.push(op2 * op1);
      else if (op == '/') 
         operandStack.push(op2 / op1);
      else if (op == '^') 
         operandStack.push((int)Math.pow(op2, op1));
      else if (op == '%') 
         operandStack.push(op2 % op1);
   }
   
   public static String insertBlanks(String s) {
      String result = "";
      
      for (int i = 0; i < s.length(); i++) {
         if (s.charAt(i) == '(' || s.charAt(i) == ')' || 
              s.charAt(i) == '+' || s.charAt(i) == '-' ||
              s.charAt(i) == '*' || s.charAt(i) == '/' ||
              s.charAt(i) == '^' || s.charAt(i) == '%')
            result += " " + s.charAt(i) + " ";
         else
            result += s.charAt(i);
      }
      
      return result;
   }
   
   /*
   OUTPUT:
       
   ----jGRASP exec: java --module-path C:\Users\rmeri\Downloads\openjfx-19_windows-x64_bin-sdk\javafx-sdk-19\lib --add-modules=javafx.controls Exercise20_23
  Enter an expression: (5 * 2 ^ 3 + 2 * 3 % 2) * 4
  (5 * 2 ^ 3 + 2 * 3 % 2) * 4 = 160
  
   ----jGRASP: operation complete.
  
   ----jGRASP exec: java --module-path C:\Users\rmeri\Downloads\openjfx-19_windows-x64_bin-sdk\javafx-sdk-19\lib --add-modules=javafx.controls Exercise20_23
  Enter an expression: 349 % 23 ^ 2 + 4 ^ 4 % 5
  349 % 23 ^ 2 + 4 ^ 4 % 5 = 605
  
   ----jGRASP: operation complete.
  
   
   */
}

我尝试过这个；

import java.util.*;

public class Exercise20_23 {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter an expression: ");
    String expression = scanner.nextLine();
    String temp = expression;
    
    try {
      System.out.println(expression + " = " + evaluateExpression(expression));
    }
    catch (Exception ex) {
      System.out.println("Wrong expression: " + temp);
    }
  }
    
  /** Evaluate an expression */
  public static int evaluateExpression(String expression) {
    // Create operandStack to store operands
    Stack<Integer> operandStack = new Stack<>();
  
    // Create operatorStack to store operators
    Stack<Character> operatorStack = new Stack<>();
  
    // Insert blanks around (, ), +, -, /, *, ^, and %
    expression = insertBlanks(expression);

    // Extract operands and operators
    String[] tokens = expression.split(" ");

    // Phase 1: Scan tokens
    for (String token: tokens) {
      if (token.length() == 0) // Blank space
        continue; // Back to the for loop to extract the next token
      else if (token.charAt(0) == '+' || token.charAt(0) == '-') {
        // Process all +, -, *, /, ^. % in the top of the operator stack 
        while (!operatorStack.isEmpty() &&
          (operatorStack.peek() == '+' || 
           operatorStack.peek() == '-' ||
           operatorStack.peek() == '*' ||
           operatorStack.peek() == '/' ||
           operatorStack.peek() == '^' ||
           operatorStack.peek() == '%')) {
          processAnOperator(operandStack, operatorStack);
        }

        // Push the + or - operator into the operator stack
        operatorStack.push(token.charAt(0));
      }
      else if (token.charAt(0) == '*' || token.charAt(0) == '/' || token.charAt(0) == '%') {
        // Process all *, /, % in the top of the operator stack 
        while (!operatorStack.isEmpty() &&
          (operatorStack.peek() == '*' ||
           operatorStack.peek() == '/' ||
           operatorStack.peek() == '%' )) {
          processAnOperator(operandStack, operatorStack);
        }

        // Push the *, /, or % operator into the operator stack
        operatorStack.push(token.charAt(0));
      }
      else if (token.charAt(0) == '^') {
        // Process all ^ in the top of the operator stack 
        while (!operatorStack.isEmpty() &&
          (operatorStack.peek() == '^')) {
          processAnOperator(operandStack, operatorStack);
        }

        // Push the ^ operator into the operator stack
        operatorStack.push(token.charAt(0));
      }
      else if (token.trim().charAt(0) == '(') {
        operatorStack.push('('); // Push '(' to stack
      }
      else if (token.trim().charAt(0) == ')') {
        // Process all the operators in the stack until seeing '('
        while (operatorStack.peek() != '(') {
          processAnOperator(operandStack, operatorStack);
        }
        
        operatorStack.pop(); // Pop the '(' symbol from the stack
      }
      else { // An operand scanned
        // Push an operand to the stack
        operandStack.push(Integer.valueOf(token));
      }
    }

    // Phase 2: Process all the remaining operators in the stack 
    while (!operatorStack.isEmpty()) {
      processAnOperator(operandStack, operatorStack);
    }

    // Return the result
    return operandStack.pop();
  }

  /** Process one operator: Take an operator from operatorStack and
   *  apply it on the operands in the operandStack */
  public static void processAnOperator(Stack<Integer> operandStack, Stack<Character> operatorStack) {
    char op = operatorStack.pop();
    int op1 = operandStack.pop();
    int op2 = operandStack.pop();
    if (op == '+') 
      operandStack.push(op2 + op1);
    else if (op == '-') 
      operandStack.push(op2 - op1);
    else if (op == '*') 
      operandStack.push(op2 * op1);
    else if (op == '/') 
      operandStack.push(op2 / op1);
    else if (op == '^') 
      operandStack.push((int)Math.pow(op2, op1));
    else if (op == '%') 
      operandStack.push(op2 % op1);
    else if (op != '(' || op != ')') {
    if (op == '%') 
      operandStack.push(op2 % op1);
    else if (op == '^') 
      operandStack.push((int)Math.pow(op2, op1));
    else if (op == '+') 
      operandStack.push(op2 + op1);
    else if (op == '-') 
      operandStack.push(op2 - op1);
    else if (op == '*') 
      operandStack.push(op2 * op1);
    else if (op == '/') 
      operandStack.push(op2 / op1);
   }
  }
  
  public static String insertBlanks(String s) {
    String result = "";
    
    for (int i = 0; i < s.length(); i++) {
      if (s.charAt(i) == '(' || s.charAt(i) == ')' || 
          s.charAt(i) == '+' || s.charAt(i) == '-' ||
          s.charAt(i) == '*' || s.charAt(i) == '/' ||
          s.charAt(i) == '^' || s.charAt(i) == '%')
        result += " " + s.charAt(i) + " ";
      else
        result += s.charAt(i);
    }
    
    return result;
  }
  
  /*
  OUTPUT:
  
  ----jGRASP exec: java --module-path C:\Users\rmeri\Downloads\openjfx-19_windows-x64_bin-sdk\javafx-sdk-19\lib --add-modules=javafx.controls Exercise20_23
 Enter an expression: (5 * 2 ^ 3 + 2 * 3 % 2) * 4
 (5 * 2 ^ 3 + 2 * 3 % 2) * 4 = 160
 
  ----jGRASP: operation complete.
 
  ----jGRASP exec: java --module-path C:\Users\rmeri\Downloads\openjfx-19_windows-x64_bin-sdk\javafx-sdk-19\lib --add-modules=javafx.controls Exercise20_23
 Enter an expression: 349 % 23 ^ 2 + 4 ^ 4 % 5
 349 % 23 ^ 2 + 4 ^ 4 % 5 = 605
 
  ----jGRASP: operation complete.
 
  */
}

但是根据此链接，这两个代码都不是我正在寻找的结果] ()

我正在尝试修改评估表达式，为运算符添加“^”、“%”字符，以便我可以完成狂欢项目，但我不知道我还需要做什么，所以如果有人可以告诉我什么上面的两段代码都是错误的，我将非常感激。

Answer 1

你已经很接近了。

我看到你正在使用jGRASP，调试这类问题就是它的用途。在主循环内的第一个语句（“if”语句）处设置断点并进行调试。从“变量”选项卡中，拖出运算符和操作数堆栈并将它们放在任意位置。这将弹出“查看器”，以便您可以观看堆栈的填满和清空。为了方便起见，您还可以打开画布并将两个变量拖到那里，如下图所示（您可以保存画布以供以后重用，这与个人查看器不同）。反复点击调试器上的“恢复”，并观察堆栈以及“令牌”变量（为了方便起见，您也可以将其拖到画布上），此时代码中的“令牌”将是要处理的“下一个”令牌。将堆栈上发生的情况与根据优先级应该发生的情况进行比较，例如 (349 % (23 ^ 2)) + ((4 ^ 4) % 5)。当您发现导致问题的操作符时，退出并重新启动调试器，恢复直到问题点，然后使用调试器“单步”和/或“单步执行”按钮逐行运行，直到看到原因。