文檔過濾器與KeyListener與MaskFormatter

Question

在你跳過我之前，請記住，你們每個人都在某個時候開始（只是因爲我看到了回覆）。是的，我正在學習，但需要一些關於DocumentFilter，KeyListener或任何其他方式之間差異的幫助，以便只允許某些數據。這是爲一個班，但我可以把它放在原樣，並獲得完全的信譽。我想限制答案選項只能是A或B（不區分大小寫）。我讀過很多文章，並且對於我閱讀的每篇文章都感到困惑。請幫助我理解。下面

代碼：

import java.util.Random; 
import java.io.*; 

public class HorticultureQuiz { 

    public static void main(String[] args) { 

     // Create a randomizer Object 
     Random rand = new Random(); 
     // Object used to read the input 
     BufferedReader input = new BufferedReader(new InputStreamReader(System.in)); 
     // String Array used to maintain the questions 
     String[][] questions = new String[10][2]; 

     //Questions - 0 throuugh 9 equals 10 questions 
     questions[0][0] = "Question1 \nA: True\nB: False"; 
     questions[1][0] = "Question2 \nA: True\nB: False"; 
     questions[2][0] = "Question3 \nA: True\nB: False"; 
     questions[3][0] = "Question4 \nA: True\nB: False"; 
     questions[4][0] = "Question5 \nA: True\nB: False"; 
     questions[4][0] = "Question5 \nA: True\nB: False"; 
     questions[5][0] = "Question6 \nA: True\nB: False"; 
     questions[6][0] = "Question7 \nA: True\nB: False"; 
     questions[7][0] = "Question8 \nA: True\nB: False"; 
     questions[8][0] = "Question9\nA: True\nB: False"; 
     questions[9][0] = "Question10 \nA: True\nB: False"; 

     //Answers 
     questions[0][1] = "B"; 
     questions[1][1] = "B"; 
     questions[2][1] = "B"; 
     questions[3][1] = "B"; 
     questions[4][1] = "B"; 
     questions[5][1] = "B"; 
     questions[6][1] = "B"; 
     questions[7][1] = "B"; 
     questions[8][1] = "B"; 
     questions[9][1] = "B"; 


     int intOption; 
     String strAnswer = null; 

     // Used to maintain the count in the loop 
     int ii = 0; 

     while (ii < 5){ 

     // Assign the input answer a value until you reach 5 
     intOption = rand.nextInt(5); 
     // Print the question to the screen 
     System.out.println(questions[intOption][0]); 
     //Error handling 
     try { 
      strAnswer = input.readLine(); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
     // If the input answer equals the correct answer in the array list 
     if (strAnswer.equals(questions[intOption][1])){ 

      // you are correct 
      System.out.println("Correct!"); 

      } 

      else{ 

      // Otherwise...WRONG 
      System.out.println("WRONG, the answer was " + questions[intOption][1]); 

      } 

     //Increment by one until you reach 5 
     ii = ii + 1; 

     } 

    } 

} 

Answer 1

添加驗證到你從用戶輸入的部分 -

 System.out.println(questions[intOption][0]); 
     // Error handling 
     try { 
      do { 
       strAnswer = input.readLine().toUpperCase(); 
      } while (!isValid(strAnswer)); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 

創建方法isValid這將檢查輸入是一個有效的輸入或不，如下圖所示：

private static boolean isValid(String strAnswer) { 
    boolean valid = strAnswer.equals("A") || strAnswer.equals("B"); 
    if(!valid){ 
     System.out.println("\nInput is not valid, please enter a valid choice - A or B"); 
    } 
    return valid; 
}