Java實現四則運算 謝雅淇 袁杏儀
https://github.com/3216004716/four-operations.git
項目相關要求
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使用 -n 參數控制生成題目的個數,例如
Myapp.exe -n 10 將生成10個題目。
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使用 -r 參數控制題目中數值(自然數、真分數和真分數分母)的範圍,例如
Myapp.exe -r 10
將生成10以內(不包括10)的四則運算題目。該參數可以設置為1或其他自然數。該參數必須給定,否則程序報錯並給出幫助信息。
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生成的題目中計算過程不能產生負數,也就是說算術表達式中如果存在形如e1 ? e2的子表達式,那麽e1 ≥ e2。
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生成的題目中如果存在形如e1 ÷ e2的子表達式,那麽其結果應是真分數。
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每道題目中出現的運算符個數不超過3個。
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程序一次運行生成的題目不能重復,即任何兩道題目不能通過有限次交換+和×左右的算術表達式變換為同一道題目。
生成的題目存入執行程序的當前目錄下的Exercises.txt文件,格式如下:
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四則運算題目1
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四則運算題目2
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其中真分數在輸入輸出時采用如下格式,真分數五分之三表示為3/5,真分數二又八分之三表示為2’3/8。
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在生成題目的同時,計算出所有題目的答案,並存入執行程序的當前目錄下的Answers.txt文件,格式如下:
1.答案1
2.答案2
特別的,真分數的運算如下例所示:1/6 + 1/8 = 7/24。
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程序應能支持一萬道題目的生成。
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程序支持對給定的題目文件和答案文件,判定答案中的對錯並進行數量統計,輸入參數如下:
Myapp.exe -e <exercisefile>.txt -a <answerfile>.txt
統計結果輸出到文件Grade.txt,格式如下:
Correct: 5 (1, 3, 5, 7, 9)
Wrong: 5 (2, 4, 6, 8, 10)
其中“:”後面的數字5表示對/錯的題目的數量,括號內的是對/錯題目的編號。為簡單起見,假設輸入的題目都是按照順序編號的符合規範的題目。
PSP:
PSP2.1 | Personal Software Process Stages | 預估耗時(分鐘) | 實際耗時(分鐘) |
---|---|---|---|
Planning | 計劃 | 10 | 15 |
· Estimate | · 估計這個任務需要多少時間 | 10 | 15 |
Development | 開發 | 1160 | 1510 |
· Analysis | · 需求分析 (包括學習新技術) | 200 | 400 |
· Design Spec | · 生成設計文檔 | 60 | 60 |
· Design Review | · 設計復審 (和同事審核設計文檔) | 30 | 20 |
· Coding Standard | · 代碼規範 (為目前的開發制定合適的規範) | 30 | 60 |
· Design | · 具體設計 | 60 | 90 |
· Coding | · 具體編碼 | 600 | 700 |
· Code Review | · 代碼復審 | 120 | 90 |
· Test | · 測試(自我測試,修改代碼,提交修改) | 60 | 90 |
Reporting | 報告 | 120 | 150 |
· Test Report | · 測試報告 | 80 | 90 |
· Size Measurement | · 計算工作量 | 10 | 20 |
· Postmortem & Process Improvement Plan | · 事後總結, 並提出過程改進計劃 | 30 | 40 |
合計 | 1290 | 1675 |
解題思路:
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取隨機操作數
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取隨機操作符
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生成表達式
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由表達式轉換為後綴表達式
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後綴表達式入棧,計算
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去重
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結果寫入文件
設計實現過程
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Utils
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RandomUtil 生成隨機操作數和隨機操作符
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ExpressionUtil 生成表達式
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CalculateUtil 封裝計算的方法
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FileUtil 生成題目和答案的文檔
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Calculate
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calculateResult 用於計算結果
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Expression
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CheckExpression 檢查重復的表達式
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MyExpression 表達式類
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PostfixExpression 生成後綴表達式
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代碼說明
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RandomUtil類 獲取隨機操作數,用了Math.random()
// 獲取隨機操作數 public static String getRandomOperand(int range) { String Operand = null; int index = (int) (Math.random() * 4); if (index == 0) {// 生成分數 index = (int) (Math.random() * 3); if (index == 2) {// 生成假分數 Operand = getImproperTractionNumber(range); } else {// 生成真分數 Operand = getTruTractionNumber(range); } } else { Operand = getNaturalNumber(range);// 生成整數 } return Operand; }
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ExpressionUtil類 獲取隨機表達式
public static MyExpression getRandomExpression(int range) { // 獲取隨機表達式 MyExpression myExpression = null; int index = (int) (Math.random() * 10); if (index <= 3) { myExpression = getOneOperExp(range);// 一個操作符 } else if (index == 4) {// 三個操作符 index = (int) (Math.random() * 2); if (index == 0) { myExpression = getThreeOperExp(range); } else { myExpression = getThreeOperExpWithBracket(range); } } else {// 兩個操作符 index = (int) (Math.random() * 2); if (index == 0) { myExpression = getTwoOperExp(range); } else { myExpression = getTwoOperExpWithBracket(range); } } CaculateResult.caculate(myExpression); // 計算結果 ? return myExpression; }
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PostfixExpression類 生成後綴表達式
private static ArrayList<String> generatePostfixExpression(String expression) { //生成String類型的後綴表達式 String[] expressionArray = expression.split(" "); ArrayList<String> postfixExpression = new ArrayList<String>(); Stack<String> stack = new Stack<String>(); for (int i = 0; i < expressionArray.length; i++) { String item = expressionArray[i]; String temp = ""; switch (item) { case "(": stack.push(item); break; case ")": while ((stack.size() != 0) && !((temp = stack.pop()).equals("("))) { postfixExpression.add(temp); } break; case "+": case "-": while ((stack.size() != 0) && !((temp = stack.pop()).equals("("))) { postfixExpression.add(temp); } if (temp.equals("(")) { stack.push(temp); } stack.push(item); break; case "×": case "÷": while ((stack.size() != 0) && !((temp = stack.pop()).equals("("))) { if (temp.equals("×") || temp.equals("÷")) { postfixExpression.add(temp); } else { stack.push(temp); break; } } if (temp.equals("(")) { stack.push(temp); } stack.push(item); break; default: postfixExpression.add(item); } } while (stack.size() != 0) { postfixExpression.add(stack.pop()); } return postfixExpression; }
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CalculateResult類 計算後綴表達式
public class CaculateResult { public static void caculate(MyExpression myExpression) { PostfixExpression.toPostfixExpression(myExpression); ArrayList<String> postfixExpression = myExpression.getPostfixExpression(); String temp = ""; Stack<String> s = new Stack<>(); String rightOperand = null; String leftOperand = null; int result = 0; int a1, a2, b1, b2 = 0; int denominator = 0; int numerator = 0; a: for (int i = 0; i < postfixExpression.size(); i++) { String item = postfixExpression.get(i); switch (item) { case "+": rightOperand = s.pop(); leftOperand = s.pop(); if (CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { result = Integer.parseInt(rightOperand) + Integer.parseInt(leftOperand); temp = String.valueOf(result); } else if (CaculateUtil.isNumeric(rightOperand) && !CaculateUtil.isNumeric(leftOperand)) { denominator = CaculateUtil.getDenominator(leftOperand); numerator = CaculateUtil.getNumerator(leftOperand); numerator = Integer.parseInt(rightOperand) * denominator + numerator; temp = numerator + "/" + denominator; } else if (!CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { denominator = CaculateUtil.getDenominator(rightOperand); numerator = CaculateUtil.getNumerator(rightOperand); numerator = Integer.parseInt(leftOperand) * denominator + numerator; temp = numerator + "/" + denominator; } else { a1 = CaculateUtil.getDenominator(rightOperand); a2 = CaculateUtil.getNumerator(rightOperand); b1 = CaculateUtil.getDenominator(leftOperand); b2 = CaculateUtil.getNumerator(leftOperand); numerator = a1 * b2 + a2 * b1; denominator = a1 * b1; temp = numerator + "/" + denominator; } s.push(temp); break; case "×": rightOperand = s.pop(); leftOperand = s.pop(); if (CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { result = Integer.parseInt(rightOperand) * Integer.parseInt(leftOperand); temp = String.valueOf(result); } else if (CaculateUtil.isNumeric(rightOperand) && !CaculateUtil.isNumeric(leftOperand)) { numerator = CaculateUtil.getNumerator(leftOperand); denominator = CaculateUtil.getDenominator(leftOperand); numerator = numerator * Integer.parseInt(rightOperand); temp = numerator + "/" + denominator; } else if (!CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { numerator = CaculateUtil.getNumerator(rightOperand); denominator = CaculateUtil.getDenominator(rightOperand); numerator = numerator * Integer.parseInt(leftOperand); temp = numerator + "/" + denominator; } else { a1 = CaculateUtil.getDenominator(rightOperand); a2 = CaculateUtil.getNumerator(rightOperand); b1 = CaculateUtil.getDenominator(leftOperand); b2 = CaculateUtil.getNumerator(leftOperand); numerator = a2 * b2; denominator = a1 * b1; temp = numerator + "/" + denominator; } s.push(temp); break; case "-": leftOperand = s.pop(); rightOperand = s.pop(); int inta, intb = 0; if (CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { inta = Integer.parseInt(rightOperand); intb = Integer.parseInt(leftOperand); result = inta - intb; temp = String.valueOf(result); } else if (CaculateUtil.isNumeric(rightOperand) && !CaculateUtil.isNumeric(leftOperand)) { inta = Integer.parseInt(rightOperand); numerator = CaculateUtil.getNumerator(leftOperand); denominator = CaculateUtil.getDenominator(leftOperand); numerator = inta * denominator - numerator; temp = numerator + "/" + denominator; } else if (!CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { intb = Integer.parseInt(leftOperand); numerator = CaculateUtil.getNumerator(rightOperand); denominator = CaculateUtil.getDenominator(rightOperand); numerator = numerator - intb * denominator; temp = numerator + "/" + denominator; } else { a1 = CaculateUtil.getDenominator(rightOperand); a2 = CaculateUtil.getNumerator(rightOperand); b1 = CaculateUtil.getDenominator(leftOperand); b2 = CaculateUtil.getNumerator(leftOperand); numerator = a2 * b1 - a1 * b2; denominator = a1 * b1; temp = numerator + "/" + denominator; } if (temp.contains("-")||temp.equals("0")) { myExpression.setCheckAnswer(false); break a; } s.push(temp); break; case "÷": leftOperand = s.pop(); rightOperand = s.pop(); int integer_a = 0, integer_b = 0; if (CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { integer_a = Integer.parseInt(rightOperand); integer_b = Integer.parseInt(leftOperand); if (integer_b == 0) { break; } else if ((integer_a % integer_b) == 0) { result = integer_a / integer_b; temp = String.valueOf(result); } else { numerator = integer_a; denominator = integer_b; temp = numerator + "/" + denominator; } } else if (CaculateUtil.isNumeric(rightOperand) && !CaculateUtil.isNumeric(leftOperand)) { integer_a = Integer.parseInt(rightOperand); numerator = CaculateUtil.getNumerator(leftOperand); denominator = CaculateUtil.getDenominator(leftOperand); int temp1 = numerator; numerator = integer_a * denominator; denominator = temp1; temp = numerator + "/" + denominator; } else if (!CaculateUtil.isNumeric(rightOperand) && CaculateUtil.isNumeric(leftOperand)) { integer_b = Integer.parseInt(leftOperand); numerator = CaculateUtil.getNumerator(rightOperand); denominator = CaculateUtil.getDenominator(rightOperand); denominator = denominator * integer_b; temp = numerator + "/" + denominator; } else { a1 = CaculateUtil.getDenominator(rightOperand); a2 = CaculateUtil.getNumerator(rightOperand); b1 = CaculateUtil.getDenominator(leftOperand); b2 = CaculateUtil.getNumerator(leftOperand); numerator = a2 * b1; denominator = a1 * b2; temp = numerator + "/" + denominator; } s.push(temp); break; default: s.push(item); break; } } myExpression.setResult(CaculateUtil.reduceFractiong(temp)); } }
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CheckExpression類 檢查重復的表達式
public class CheckExpression { ? public static boolean checkRepeated(MyExpression expression1, MyExpression expression2) { boolean flag = true; if (expression1.getPostfixExpression().size() == expression2.getPostfixExpression().size()) { if (expToString(expression1.getPostfixExpression()).equals(expToString(expression2.getPostfixExpression())) || changePosition(expression1).equals(expToString(expression2.getPostfixExpression()))) { flag = false; } } return flag; } ? static String changePosition(MyExpression expression) { ArrayList<String> postfixExpression = expression.getPostfixExpression(); String firstOperator = getFirstOperator(postfixExpression); if (firstOperator.equals("+") || firstOperator.equals("×")) { int index = postfixExpression.indexOf(firstOperator); String temp = postfixExpression.get(index - 1); postfixExpression.set(index - 1, postfixExpression.get(index - 2)); postfixExpression.set(index - 2, temp); } ? return expToString(postfixExpression); } ? static String getFirstOperator(ArrayList<String> postfixExpression) { String operator = ""; for (int i = 0; i < postfixExpression.size(); i++) { String item = postfixExpression.get(i); if (item.equals("+") || item.equals("-") || item.equals("×") || item.equals("÷")) { operator = item; break; } } return operator; } ? public static String expToString(ArrayList<String> PostfixExpression) { String string = null; for (int i = 0; i < PostfixExpression.size(); i++) { string += PostfixExpression.get(i); } return string; } }
運行結果
項目小結
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謝雅淇:我覺得這次程序的編寫,我只是在為了解決問題而寫方法的代碼,沒有很好地融入面向對象的思想。還有在寫代碼之前就要把思路理清楚,不然代碼就會寫的很亂,不僅會浪費時間,還會把代碼寫得非常冗長,可觀性比較差。這次作業的結對隊友,從討論需求到編寫代碼的過程中都幫助了我很多,我覺得我需要提升的地方還有很多,以後還需要繼續努力,多加練習。
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袁杏儀:我覺得這次程序的編寫,讓我對開發程序有了更深入的了解,體會到溝通與合作的重要性,同時也感受到團隊開發的樂趣,還收獲了真摯的友誼。這次作業,讓我感觸最深的是我們寫完代碼後測試時,得出結果然後進行驗算,檢查出錯答案並對源代碼進行修改的過程,每一次修改,一步步得出正確的結果,這讓我非常有成就感。
Java實現四則運算 謝雅淇 袁杏儀