java - 如何在堆栈问题中使用字符数组（或字节数组）逐行读取
问题描述
这是一个后续问题： 如何将堆栈中的内容打印到文件中
我刚刚意识到分配限制了字符串函数的使用。我还没有使用 char 数组逐行读取。而不是我可以得到的结果：
--- EVALUATION BEGINS ---
EXAMPLE 1:
Postfix Expression: AB+C-
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
EXAMPLE 2:
Postfix Expression: ABC+-
Instructions in the Register:
LD B
AD C
ST TEMP1
LD A
SB TEMP1
ST TEMP2
EXAMPLE 3:
Postfix Expression: AB-C+DEF-+$
Instructions in the Register:
LD A
SB B
ST TEMP1
LD TEMP1
AD C
ST TEMP2
LD E
SB F
ST TEMP3
LD D
AD TEMP3
ST TEMP4
LD TEMP2
EX TEMP4
ST TEMP5
EXAMPLE 4:
Postfix Expression: ABCDE-+$*EF*-
Instructions in the Register:
LD D
SB E
ST TEMP1
LD C
AD TEMP1
ST TEMP2
LD B
EX TEMP2
ST TEMP3
LD A
ML TEMP3
ST TEMP4
LD E
ML F
ST TEMP5
LD TEMP4
SB TEMP5
ST TEMP6
EXAMPLE 5:
Postfix Expression: ABC+*CBA-+*
Instructions in the Register:
LD B
AD C
ST TEMP1
LD A
ML TEMP1
ST TEMP2
LD B
SB A
ST TEMP3
LD C
AD TEMP3
ST TEMP4
LD TEMP2
ML TEMP4
ST TEMP5
EXAMPLE 6:
Postfix Expression: ABC+/CBA*+
Instructions in the Register:
LD B
AD C
ST TEMP1
LD A
DV TEMP1
ST TEMP2
LD B
ML A
ST TEMP3
LD C
AD TEMP3
ST TEMP4
EXAMPLE 7:
Postfix Expression: AB-*CBA+-*
Instructions in the Register:
LD A
SB B
ST TEMP1
The expression is invald. Exiting program now...
StackException: EMPTY STACK ON ARG2
EXAMPLE 8:
Postfix Expression: ABC-/BA-+/
Instructions in the Register:
LD B
SB C
ST TEMP1
LD A
DV TEMP1
ST TEMP2
LD B
SB A
ST TEMP3
LD TEMP2
AD TEMP3
ST TEMP4
The expression is invald. Exiting program now...
StackException: EMPTY STACK ON ARG2
EXAMPLE 9:
Postfix Expression: ABC+$CBA-+*
Instructions in the Register:
LD B
AD C
ST TEMP1
LD A
EX TEMP1
ST TEMP2
LD B
SB A
ST TEMP3
LD C
AD TEMP3
ST TEMP4
LD TEMP2
ML TEMP4
ST TEMP5
EXAMPLE 10:
Postfix Expression: AB0+/CBA+-/
Instructions in the Register:
The expression is invald. Exiting program now...
StackException: Unidentified operator or operand encoutered: 0 at position: 2
EXAMPLE 11:
Postfix Expression: ABC*+DE-/
Instructions in the Register:
LD B
ML C
ST TEMP1
LD A
AD TEMP1
ST TEMP2
LD D
SB E
ST TEMP3
LD TEMP2
DV TEMP3
ST TEMP4
EXAMPLE 12:
Postfix Expression: AB#CD@EF
Instructions in the Register:
The expression is invald. Exiting program now...
StackException: Unidentified operator or operand encoutered: # at position: 2
EXAMPLE 13:
Postfix Expression: AB*CD-/E
Instructions in the Register:
LD A
ML B
ST TEMP1
LD C
SB D
ST TEMP2
LD TEMP1
DV TEMP2
ST TEMP3
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 14:
Postfix Expression: 12*34-+5$
Instructions in the Register:
The expression is invald. Exiting program now...
StackException: Unidentified operator or operand encoutered: 1 at position: 0
EXAMPLE 15:
Postfix Expression: thisislab1
Instructions in the Register:
The expression is invald. Exiting program now...
StackException: Unidentified operator or operand encoutered: t at position: 0
--- EVALUATION COMLETE ---
现在，在 PostFixEvalNew 类中重写代码希望使用 char 数组逐行读取输入文件后，我得到了这个：
--- EVALUATION BEGINS ---
EXAMPLE 1:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 2:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 3:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 4:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 5:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 6:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
EXAMPLE 7:
Postfix Expression: AB+C-
ABC+-
AB-C+DEF-+$
ABC
Instructions in the Register:
LD A
AD B
ST TEMP1
LD TEMP1
SB C
ST TEMP2
LD B
AD C
ST TEMP3
LD A
SB TEMP3
ST TEMP4
LD A
SB B
ST TEMP5
LD TEMP5
AD C
ST TEMP6
LD E
SB F
ST TEMP7
LD D
AD TEMP7
ST TEMP8
LD TEMP6
EX TEMP8
ST TEMP9
The expression is invald. Exiting program now...
StackException: Leftover variables after evaluation.
--- EVALUATION COMLETE ---
不完全确定我在这里做错了什么。很感谢任何形式的帮助！！
public class StackException extends Exception {
public StackException(String message) {
super(message);
}
}
public class Stack {
private final int stackSize = 100;
private String[] stackArray;
private int stackTop; //empty stack
Stack() {
stackArray = new String[stackSize];
stackTop = -1;
}
public boolean isEmpty() {
if(stackTop == -1)
return true;
else
return false;
}
public void push(String input) throws StackException {
if(stackTop == stackSize -1) {
throw new StackException("Stack Overflow. Exiting program now...");
}
stackArray[++stackTop] = input;
}
public int size() {
return stackTop + 1;
}
public String peek() throws StackException {
if (isEmpty()) {
throw new StackException("Stack Underflow. Exiting program now...");
}
return stackArray[stackTop];
}
public String pop() throws StackException {
if (isEmpty()) {
throw new StackException("Stack Underflow. Exiting program now...");
}
return stackArray[stackTop--];
}
}
import java.io.*;
import java.util.*;
public class PostFixEvalNew {
public static void main(String[]args) throws StackException, IOException {
File fin = new File(args[0]);
boolean fileExist = fin.exists();
File fout = new File(args[1]);
PrintWriter pw = new PrintWriter(new FileWriter(fout));
if(fileExist == true) {
pw.println("\n" + "\t\t\t\t" + "--- EVALUATION BEGINS ---");
parseFromFile(args[0], pw);
}
else {
translate(args[0], pw);
}
pw.println("\t\t\t\t" + "--- EVALUATION COMLETE ---" + "\n");
pw.close();
}
public static void parseFromFile(String input, PrintWriter pw) {
String line;
int lineCounter = 0;
char[] content = new char[(int)input.length()];
int c = 0;
try {
BufferedReader br = new BufferedReader(new FileReader(input));
try {
// while ((line = br.readLine()) != null) {
while((c = br.read(content)) != -1) {
for(int i = 0; i < c; i++) {
// br.read(content);
line = new String(content);
lineCounter++;
pw.println("EXAMPLE " + lineCounter + ": ");
pw.println("Postfix Expression: " + line);
try {
translate(line, pw);
} catch (Exception e){
pw.println("The expression is invald. Exiting program now...");
pw.println(e);
}
pw.println("\n");
}
br.close();
}
}
catch (java.io.IOException e) {
pw.println("End of File!");
}
}
catch (java.io.FileNotFoundException e) {
pw.println("File: " + input + " not found!");
return;
}
}
private static boolean isOperator(String operator) {
switch(operator) {
case "+":
case "-":
case "*":
case "/":
case "$":
return true;
default:
return false;
}
}
private static String instruction(String oper) {
switch(oper) {
case "+":
return "AD";
case "-":
return "SB";
case "*":
return "ML";
case "/":
return "DV";
case "$":
return "EX";
default:
return "N/A";
}
}
public static void translate(String expression, PrintWriter pw)
throws StackException {
Stack variables = new Stack();
int tempNum = 1;
String arg1;
String arg2;
String command;
pw.println("Instructions in the Register:");
if (expression.trim().length() == 0) {
throw new StackException("EMPTY STACK");
}
for (int i=0; i<expression.length(); i++){
//if operator, pop arguments and evaluate
if (isOperator(expression.substring(i, i+1))){
if (variables.isEmpty()) {
throw new StackException("EMPTY STACK");
}
command = instruction(expression.substring(i, i+1));
try {
arg1 = variables.pop();
} catch (StackException e) {
throw new StackException("EMPTY STACK ON ARG1");
}
try {
arg2 = variables.pop();
} catch (StackException e) {
throw new StackException("EMPTY STACK ON ARG2");
}
variables.push("TEMP" + tempNum);
pw.println("LD " + arg2);
pw.println(command + " " + arg1);
pw.println("ST " + "TEMP" + tempNum);
tempNum++;
} else if (Character.isLetter(expression.charAt(i))) {
//if variable, push onto stack
variables.push(expression.substring(i, i+1));
} else if (Character.isWhitespace(expression.charAt(i))) {
//Ignore whitespace
continue;
} else {
throw new StackException("Unidentified operator or operand encoutered: " +
expression.charAt(i) +
" at position: " + i);
}
}
if (variables.isEmpty() == false) {
while (variables.isEmpty() == false) {
if (variables.pop().startsWith("TEMP") == false){
throw new StackException("Leftover variables after evaluation.");
}
}
}
}
}