Javaセミナー2014/阪口政徳のバックアップ(No.5)

[[Javaセミナー2014/阪口政徳/宿題]
20141217夕方に桁数チェックを中心に大幅修正しました。符号抜きの整数部分と小数部分の桁数が15桁以内かどうかを入力・計算結果双方でチェックするように替えています。
[20141213宿題]
import java.io.*;
import java.lang.*;
import java.math.*;
import java.util.regex.PatternSyntaxException;
import java.util.regex.*;

public class Calc {
  static String currentData = "";
  static String currentOperator = "+";
  static BigDecimal currentResult = new BigDecimal(0);
  static boolean isNotEndOfWhile = true;
  static BufferedReader br = null;

  /*定数*/
  static final int MAX_DIGIT = 15;
  static final String START_COMMENT = "計算機アプリを開始します。";
  static final String NUMBER_INPUT_COMMENT = "数字を入力してください:";
  static final String NUMBER_Operator_Q_INPUT_COMMENT = "数字・演算子・qを入力してください。";
  static final String NUMBER_Operator_Q_INPUT_COMMENT_FOR_DIVIDE = "0以外の数字・演算子・qを入力してください。";
  static final String SITEIKETASU_COMMENT = "最大桁数";
  static final String OVER_COMMENT = "をオーバーしています。";
  static final String SAIDO_INPUT_COMMENT = "もう1度入力してください。";
  static final String END_COMMENT = "計算機アプリを終了します。";
  static final String RESET_COMMENT = "値をリセットしました。";
  static final String Operator_CHANGE_COMMENT = "演算子を変更します。";
  static final String ZERO_DIVIDE_COMMENT = "0で除算しようとしました。";

  public static void main (String[] args) throws IOException, NumberFormatException {
    
    try {
      br = new BufferedReader(new InputStreamReader(System.in));
      System.out.println(START_COMMENT);
      System.out.print(NUMBER_INPUT_COMMENT);
      currentData = br.readLine();
      currentData = currentData.trim();
      while (isNotEndOfWhile) {
        makeValidation();
      }
    } catch (NumberFormatException nEx) {
      System.out.println(nEx.toString());
    } catch (ArithmeticException aEx) {
      System.out.println(aEx.toString());
    } catch (PatternSyntaxException pEx) {
      System.out.println(pEx.toString());
    } finally {
      if(br != null) {
        br.close();
      }
    }
  }

  private static void makeValidation()
  throws NumberFormatException, IOException,
         ArithmeticException, PatternSyntaxException {
    if (currentData == null || currentData.isEmpty()) {
      System.out.println(NUMBER_Operator_Q_INPUT_COMMENT);
      readLineInputData();
    } else if (currentData.matches("^[qQ]$")) {
      System.out.println(END_COMMENT);
      isNotEndOfWhile = false;
      return;
    } else if (currentData.matches("^\\=$")) {
      System.out.println(" = " + currentResult.toPlainString());
      currentResult = new BigDecimal(0.0);//値のリセット
      readLineInputData();
    } else if (currentData.matches("^[\\+\\-]?\\d+(\\.\\d+)?$")) {
      calculate();
      readLineInputData();
    } else if(currentData.matches("^[\\+\\-\\*/]$")){
      currentOperator = currentData;
      readLineInputData();
    } else {
      System.out.println(NUMBER_Operator_Q_INPUT_COMMENT);
      readLineInputData();
    }
  }

  private static void readLineInputData() throws IOException{
    System.out.print(currentResult.toPlainString() + " " + currentOperator + " ");
    currentData = br.readLine();
    currentData = currentData.trim();
  }

  private static boolean isDigitAvialable (String examData) {
    BigDecimal bigDecimalExamData = new BigDecimal(examData);
    String strBDExamData = bigDecimalExamData.toPlainString().replaceFirst("[\\+\\-]", "");

    int totalLength    = strBDExamData.length();
    int integerLength  = 0;
    int fractionLength = 0;

    integerLength  = strBDExamData.indexOf(".") == -1 ? totalLength : strBDExamData.indexOf(".");
    fractionLength = strBDExamData.indexOf(".") == -1 ? 0           : totalLength - integerLength - 1;

    if (integerLength <= MAX_DIGIT && fractionLength <=  MAX_DIGIT) {
      return true;
    } else {
      System.out.println(SITEIKETASU_COMMENT + "(" + MAX_DIGIT + ")" + OVER_COMMENT);
      System.out.println(SAIDO_INPUT_COMMENT);
      return false;
    }
  }

  private static void calculate ()
  throws NumberFormatException, IOException, ArithmeticException{
    BigDecimal temp_currentResult =  currentResult;
    BigDecimal bigDecimalCurrentData = new BigDecimal(currentData);

    if(!isDigitAvialable(currentData)){
      return;
    }

    switch (currentOperator.charAt(0)){
      case '+':
        temp_currentResult = currentResult.add(bigDecimalCurrentData);
        break;
      case '-':
        temp_currentResult = currentResult.subtract(bigDecimalCurrentData);
        break;
      case '*':
        temp_currentResult = currentResult.multiply(bigDecimalCurrentData);
        break;
      case '/':
        Double doubleCurrentData = Double.parseDouble(currentData);
        if (doubleCurrentData == 0) {
          System.out.println(NUMBER_Operator_Q_INPUT_COMMENT_FOR_DIVIDE);
          return;
        } else {
          try{
            temp_currentResult = currentResult.divide(bigDecimalCurrentData);
          }catch(ArithmeticException aEx){
            temp_currentResult = currentResult.divide(bigDecimalCurrentData,
                                                 MAX_DIGIT ,
                                                 BigDecimal.ROUND_HALF_UP);
          }
        }
        break;
      default:
        throw new IOException();
    }

    if(isDigitAvialable(temp_currentResult.toPlainString())) {
      currentResult = temp_currentResult;
    }
  }
}