根據請求記錄計算打印的計算器

Question

我不知道我的標題是否非常具有說明性。我是新來的Java（1周）。如果我用一些詞或表達方式錯誤，請原諒我。 xD

我剛剛製作了我自己的計算器。沒有其他來源的幫助，我做得非常好。很高興開始記住我自己的Java語法。 ：d

這是我提出的計算器的代碼：

// Calc with the switch statement. 

進口java.util.Scanner中;

公共類Calcswitch { 公共靜態無效的主要（字串[] args）{

// Different variables 

    Scanner input = new Scanner(System.in); 

    double fnum = 0; 
    double snum = 0; 
    double answer = 0; 
    int whatOperation; 

    String finalquestion = ""; 
    boolean calculateAgain = true; // Goes inside the while loop 


    while (calculateAgain) { 
    // Ask what type of calculation you want to perform. 
    System.out.println("\n"); 
    System.out.println("Press 1 for +"); 
    System.out.println("Press 2 for -"); 
    System.out.println("Press 3 for *"); 
    System.out.println("Press 4 for /"); 

    whatOperation = input.nextInt(); 


    switch (whatOperation) { 

    case 1: 
     // Addition 
     System.out.print("Enter first number: "); 
     fnum = input.nextInt(); 
     System.out.print("Enter second number: "); 
     snum = input.nextInt(); 

     System.out.print("The result is: "); 
     System.out.print(fnum + snum); 
     break; 

    case 2: 
     // Subtraction 
     System.out.print("Enter first number: "); 
     fnum = input.nextInt(); 
     System.out.print("Enter second number: "); 
     snum = input.nextInt(); 

     System.out.print("The result is: "); 
     System.out.print(fnum - snum); 
     break; 

    case 3: 
     // Multiplication 
     System.out.print("Enter first number: "); 
     fnum = input.nextInt(); 
     System.out.print("Enter second number: "); 
     snum = input.nextInt(); 

     System.out.print("The result is: "); 
     System.out.print(fnum * snum); 
     break; 

    case 4: 
     // Division 
     System.out.print("Enter first number: "); 
     fnum = input.nextInt(); 
     System.out.print("Enter second number: "); 
     snum = input.nextInt(); 

     System.out.print("The result is: "); 
     System.out.print(fnum/snum); 
     break; 

     default: 
      System.out.print("You have entered an invalid number. "); 
      break; 

     } 

    // Asks if you want to use the Calculator again 
    System.out.print("\n\nDo you want to use the calculator again? Yes/No: "); 
    finalquestion = input.next(); 

    // If no, the string calculateAgain goes false, and exit the while loop. 
    if (finalquestion.equalsIgnoreCase("no")) { 


     calculateAgain = false; 


    } 


    } 

    // After the while loop. 
    System.out.println("Thank you for using this calculator"); 
} 

}

現在我想實現一個整潔的小功能，記錄的答案。如果用戶在開始使用該程序後想看到他的計算結果，他可以通過編寫「日誌記錄」或類似的方法來完成。

問題是。我不確定我如何記錄答案。一種方法是製作大量字符串並將其保留爲空。不過，我猜這不會很動態。如果我有10個用於記錄的已聲明字符串，但用戶已完成15次計算，會發生什麼？這不太好。

java是否有一種記錄用戶輸入的方法，並以動態方式存儲，以後很容易調用？

Answer 1

怎麼樣一個大的字符串，添加一個新行每個日誌

String LOG = "LOG INFO"; 

// WHEN YOU WANT TO ADD A LOGENTRY TO YOUR LOG 
String NewLogEntry = "REPLACE_WITH_YOUR_LOG_INFO"; 
LOG = LOG + /n + NewLogEntry;