循环和效率Java程序

Question

以下是我正在上课的项目。 分配的目的是获取后缀表达式并将其转换为汇编语言指令。 第一次运行后，我无法使循环打印出正确的说明。 有人可以向我解释我做错了什么吗，因为我已经调试了一段时间，但仍卡住了？ 另外，由于我是java的新手，所以对如何使我的程序更高效的任何注释或您想指出的对我学习的任何解释都将不胜感激。 我敢肯定还有更多方法可以做到这一点，但是请记住我是新手，有些事情我还没学到。

.txt输入文件上的内容：

AB + C- //循环1

ABC +-//循环2

AB-C + DEF-+ $ //循环3

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;


public class PostfixConverter{

static int top = 0;
static  String [] mainStack = new String [100];

public static void main(String args[]) throws Exception{
 String string = null;
 String asterisk = "*";
 String divisor = "/";
 String plus = "+";
 String minus = "-";
 int temp =0;
 int directionCounter = 0;
 String load = "LD ";
 String multiply = "ML ";
 String add = "AD ";
 String div = "DV ";
 String subtract = "SB ";
 String store = "ST TEMP";
 String tempString = "TEMP";
 String [] directions = new String [100];
 String example = "AB+C-";
 PostfixConverter s = new PostfixConverter();

 try{
 //file reader code
 FileReader file = new FileReader     ("/Users/ChristopherSchubert/Desktop/PostfixMachineLangInput(1).txt");
 BufferedReader reader = new BufferedReader(file);


 String text = "";
 String line = reader.readLine();
 while (line!= null)
 {
    text += line;
    line = reader.readLine();
    example = text;

  //for loop to print directions 
  for (int i=0; i<example.length(); i++) {


     //get letter entered by user 1 by 1
     char letter  = example.charAt(i);

     //convert char to string
     String convertedChar = java.lang.String.valueOf(letter);

     //finds operands in order or priority
     //multiply character
     if (convertedChar.equals(asterisk)){
        String outcome;
        String multiplyReturn = PostfixConverter.multiply(string);
        String loadmulReturn = PostfixConverter.multiply(string);
        directions[directionCounter] = load + loadmulReturn;
        directionCounter++;
        directions[directionCounter] = multiply + multiplyReturn;
        directionCounter++;
        temp++;
        outcome = tempString + java.lang.String.valueOf(temp);
        directions[directionCounter] = store +     java.lang.String.valueOf(temp);
        directionCounter++;
        s.push(outcome);
        }


        //division character
        else if (convertedChar.equals(divisor)){
           String outcome;
           String divisionReturn = PostfixConverter.addition(string);
           String loaddivReturn = PostfixConverter.addition(string);
           directions[directionCounter] = load + loaddivReturn;
           directionCounter++;
           directions[directionCounter] = div + divisionReturn;
           directionCounter++;
           temp++;
           outcome = tempString + java.lang.String.valueOf(temp);
           directions[directionCounter] = store + java.lang.String.valueOf(temp);
           directionCounter++;
           s.push(outcome);
        }

        //addition character
        else if (convertedChar.equals(plus)){
           String outcome;
           String additionReturn = PostfixConverter.addition(string);
           String loadAddReturn = PostfixConverter.addition(string);
           directions[directionCounter] = load + loadAddReturn;
           directionCounter++;
           directions[directionCounter] = add + additionReturn;
           directionCounter++;
           temp++;
           outcome = tempString + java.lang.String.valueOf(temp);
           directions[directionCounter] = store + java.lang.String.valueOf(temp);
           directionCounter++;
           s.push(outcome);
        }

        //subtraction character
        else if (convertedChar.equals(minus)){
           String outcome;
           String subtractionReturn = PostfixConverter.addition(string);
           String loadsubReturn = PostfixConverter.addition(string);
           directions[directionCounter] = load + loadsubReturn;
           directionCounter++;
           directions[directionCounter] = subtract + subtractionReturn;
           directionCounter++;
           temp++;
           outcome = tempString + java.lang.String.valueOf(temp);
           directions[directionCounter] = store +  java.lang.String.valueOf(temp);
           directionCounter++;
           s.push(outcome);
        }

        //letter character
        else {
           s.push(convertedChar);
        }

  }

  //print out the instructions
  System.out.println("Assembly Directions are as follows: ");
  int printDirections = 0;
  for (int i=0; i< directionCounter; i++){
        System.out.println(directions[printDirections]);
        printDirections++;
  }
  printDirections=0;
  directionCounter=0;
  System.out.println("This is the end of the directions.");
  System.out.println("");
  directionCounter = 0;
  temp = 0;
  top = 0;

 }
}
 catch (FileNotFoundException exception)
 {
     System.out.println("The file was not found.");
   }
 }


 //multiply method
 public static String multiply(String a){
    String multVariable = PostfixConverter.pop(mainStack[top]);
    top--;
    return multVariable;
 }

 //addition method
 public static String addition(String a){

    String addVariable = PostfixConverter.pop(mainStack[top]);
    top--;
    return addVariable;
 }

 //subtraction method
 public static String subtraction(String a){
  String subVariable = PostfixConverter.pop(mainStack[top]);
  top--;
  return subVariable;
 }

 //division method
 public static String division(String a){
  String divVariable = PostfixConverter.pop(mainStack[top]);
  top--;
  return divVariable;
  }

 public static boolean empty(){
  if (top == -1)
     return true;
  else 
     return false;

 }

 public static String pop(String j){
  if (empty()){
     System.out.println("Stack Underflow");
     System.exit(1);
    }
   return mainStack[top - 1];
 }

 public void push (String x){
  if (top == 99){
     System.out.println("Stack Overflow");
     System.exit(1);
  }else
     mainStack[top] = x;
     top++;
 }//end push

}

这是正在打印的内容：

循环1：

组装方向如下：

LD A

公元

温度1

LD温度1

SB C

圣温度2

这是指示的结尾。 //看起来是正确的

循环2：

组装方向如下：

LD A //从上面复制

公元

温度1

LD温度1

SB C

圣温度2

LD B //第二个循环实际开始的地方

公元C

圣温度3

LD A

SB TEMP3

ST TEMP4

这是指示的结尾。

Answer 1

我稍稍更改了文件的读取方式，并包含了经过调整的代码得到的输出。 让我知道这是否会产生预期的结果：

 String line = "";

 while ((line = reader.readLine()) != null)
 {
    example = line;
    // Continue to process ...

编辑：这是一种更具模块化的方法，它演示了我在注释中所指的内容（请注意“ processOperand（）”的引入，以及它如何使代码更具可读性）。 这只是寻找通用代码，并使其在各种情况下“可用”的示例（即，每个操作调用传递唯一参数的相同代码块）

public class PostfixConverter {

    static int top = 0;
    static String[] mainStack = new String[100];

    final static String asterisk = "*";
    final static String divisor = "/";
    final static String plus = "+";
    final static String minus = "-";
    final static String store = "ST TEMP";

    static int temp = 0;
    static int directionCounter = 0;
    static String[] directions = new String[100];
    static PostfixConverter s = new PostfixConverter();
    static String tempString = "TEMP";

    public static void main(String args[]) throws Exception {

        String string = null;

        String load = "LD ";
        String multiply = "ML ";
        String add = "AD ";
        String div = "DV ";
        String subtract = "SB ";

        String example = "AB+C-";

        try {
            // file reader code
            FileReader file = new FileReader("....");
            BufferedReader reader = new BufferedReader(file);

            String line = "";

            while ((line = reader.readLine()) != null) {
                example = line;

                // for loop to print directions
                for (int i = 0; i < example.length(); i++) {

                    // get letter entered by user 1 by 1
                    char letter = example.charAt(i);

                    // convert char to string
                    String convertedChar = java.lang.String.valueOf(letter);

                    // finds operands in order or priority
                    // multiply character
                    if (convertedChar.equals(asterisk)) {

                        processOperand(PostfixConverter.multiply(string), PostfixConverter.multiply(string), load,
                                multiply);
                    }

                    // division character
                    else if (convertedChar.equals(divisor)) {
                        processOperand(PostfixConverter.addition(string), PostfixConverter.addition(string), load, div);
                    }

                    // addition character
                    else if (convertedChar.equals(plus)) {
                        processOperand(PostfixConverter.addition(string), PostfixConverter.addition(string), load, add);
                    }

                    // subtraction character
                    else if (convertedChar.equals(minus)) {
                        processOperand(PostfixConverter.addition(string), PostfixConverter.addition(string), load,
                                subtract);

                    }
                    // letter character
                    else {
                        s.push(convertedChar);
                    }

                }

                // print out the instructions
                System.out.println("Assembly Directions are as follows: ");
                int printDirections = 0;
                for (int i = 0; i < directionCounter; i++) {
                    System.out.println(directions[printDirections]);
                    printDirections++;
                }
                printDirections = 0;
                directionCounter = 0;
                System.out.println("This is the end of the directions.");
                System.out.println("");
                directionCounter = 0;
                temp = 0;
                top = 0;

            }
        } catch (FileNotFoundException exception) {
            System.out.println("The file was not found.");
        }
    }

    private static void processOperand(String postFileConverterOutput, String postFileConverterOutput2,
            String instruction1, String instruction2) {
        String outcome;
        String opReturn1 = postFileConverterOutput;
        String opReturn2 = postFileConverterOutput2;
        directions[directionCounter] = instruction1 + opReturn2;
        directionCounter++;
        directions[directionCounter] = instruction2 + opReturn1;
        directionCounter++;
        temp++;
        outcome = tempString + java.lang.String.valueOf(temp);
        directions[directionCounter] = store + java.lang.String.valueOf(temp);
        directionCounter++;
        s.push(outcome);
    }

    // multiply method
    public static String multiply(String a) {
        String multVariable = PostfixConverter.pop(mainStack[top]);
        top--;
        return multVariable;
    }

    // addition method
    public static String addition(String a) {

        String addVariable = PostfixConverter.pop(mainStack[top]);
        top--;
        return addVariable;
    }

    // subtraction method
    public static String subtraction(String a) {
        String subVariable = PostfixConverter.pop(mainStack[top]);
        top--;
        return subVariable;
    }

    // division method
    public static String division(String a) {
        String divVariable = PostfixConverter.pop(mainStack[top]);
        top--;
        return divVariable;
    }

    public static boolean empty() {
        if (top == -1)
            return true;
        else
            return false;

    }

    public static String pop(String j) {
        if (empty()) {
            System.out.println("Stack Underflow");
            System.exit(1);
        }
        return mainStack[top - 1];
    }

    public void push(String x) {
        if (top == 99) {
            System.out.println("Stack Overflow");
            System.exit(1);
        } else
            mainStack[top] = x;
        top++;
    }// end push

}

创建以下内容的输出：

Assembly Directions are as follows: 
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
This is the end of the directions.

Assembly Directions are as follows: 
LD B
AD C
ST TEMP1
LD A
SB TEMP1
ST TEMP2
This is the end of the directions.

Assembly Directions are as follows: 
LD A
SB B
ST TEMP1
LD TEMP1
AD C
ST TEMP2
LD E
SB F
ST TEMP3
LD D
AD TEMP3
ST TEMP4
This is the end of the directions.