爲什麼char值在輸出期間轉換？

我正在讓我的程序在Java SE中爲一個學校作業投擲一個東西（如骰子）。用戶可以將一個角色作爲標準輸入，所以用戶選擇的角色將代表骰子的眼睛。有時當我打印結果時，它顯示出完全不同的字符。爲什麼char值在輸出期間轉換？

package ThrowADie; 
import java.util.Scanner; 

public class ThrowADie { 

public static void main(String[] args) { 

    //Ask user for the char in which the dices eyes should be printed in. 
    System.out.print("Which character should I use for the eye: "); 

    //Allow user to place input in the eye variable 
    Scanner input = new Scanner(System.in); //Make the stdinput object 
    char eye = input.next().charAt(0); 

    //Time to throw the die. Place result in dieResult 
    int dieResult = throwDie(); 

    //Reveal of the result 
    printDieResult(dieResult, eye); 

} 


    /* 
    * Method name: throwDie() 
    * Purpose: Picks a number from 1 to 6 randomly, like a die does 
    * Parameters: N/A 
    * Returns: Integer number from 1 to 6  
    */ 
    public static int throwDie(){ 
     int range = (6 - 1) + 1;  
     return (int)(Math.random() * range) + 1; 
    } 


    /* 
    * Method name: printDieResult() 
    * Purpose: Generate result of the die throw in ASCII art 
    * Parameters: numberOfEyes, typeOfEyes 
    * Returns: N/A 
    */ 
    public static void printDieResult(int numberOfEyes, char typeOfEyes){ 
     if (numberOfEyes == 1){ 
      //Print art 
      System.out.println(
        " " + " " + " \n" 
        + " " + typeOfEyes + " \n" 
        + " " + " " + " "); 
     } else if (numberOfEyes == 2){ 
      //Print art 
      System.out.println(
        typeOfEyes + " " + " \n" 
        + " " + " " + " \n" 
        + " " + " " + typeOfEyes); 
     } else if (numberOfEyes == 3){ 
      //Print art 
      System.out.println(
        typeOfEyes + " " + " \n" 
        + " " + typeOfEyes + " \n" 
        + " " + " " + typeOfEyes); 
     } else if (numberOfEyes == 4){ 
      //Print art 
      System.out.println(
        typeOfEyes + " " + typeOfEyes + "\n" 
        + " " + " " + " \n" 
        + typeOfEyes + " " + typeOfEyes); 
     } else if (numberOfEyes == 5){ 
      //Print art 
      System.out.println(
        typeOfEyes + " " + typeOfEyes + "\n" 
        + " " + typeOfEyes + " \n" 
        + typeOfEyes + " " + typeOfEyes); 
     } else { 
      //Print art 
      //Accidentally written down 9 eye representation 
      System.out.println(
        typeOfEyes + typeOfEyes + typeOfEyes + "\n" 
        + typeOfEyes + typeOfEyes + typeOfEyes + "\n" 
        + typeOfEyes + typeOfEyes + typeOfEyes); 
     } 
    } 
}

輸出這一計劃將產生正確的結果。但偶爾，已經輸入的代表死亡之眼的字符轉換爲數字。

在下面的情況下，程序應該打印9個'@'字符。相反，它在第一行打印192。（我知道骰子有6隻眼睛，但我碰到了這個陌生的輸出，而意外打印9隻眼）

run: 
Which character should I use for the eyes: @ 
192 
@@@ 
@@@

我找不到這個原因，任何人都可以看到我做了什麼錯在這裏？

來源

2014-09-26 Lee

字符算術！

請諮詢此table。 @是字符64

typeOfEyes + typeOfEyes + typeOfEyes + "\n"

此第一行實際上是相加的字符（64 + 64 + 64）= 192的值，則addending與換行，所以我們得到192\n。

編譯器選擇添加它們而不是創建字符串。解決這個問題的簡單方法是在前面加上一個空字符串："" + typeOfEyes...

基本上，編譯器是「愚蠢的」。當我們將整數添加到字符串"foo" + 123時，編譯器可以將其解釋爲foo123，因爲它將第一個元素識別爲字符串。但是，我們已經定義了一個char這是一個代表字符的numeric類型。所以編譯器會和它進行數學運算。即使我們不應該。添加字符串文字告訴它我們實際上需要文本。

來源

2014-09-26 19:43:27 Compass

本質上，這些求和之間缺少一個字符串。 – Makoto 2014-09-26 19:44:22

精彩的解釋。我覺得有必要說：謝謝！ – Lee 2014-09-26 19:57:08

int test = (int) (typeOfEyes + typeOfEyes + typeOfEyes); 

     System.out.println("\n" + test + "\n" 
       + typeOfEyes + "" + typeOfEyes + "" + typeOfEyes + "\n" 
       + typeOfEyes + "" + typeOfEyes + "" + typeOfEyes + "\n" 
       + typeOfEyes + "" + typeOfEyes + "" + typeOfEyes); 

Which character should I use for the eye: @ 

192 
@@@ 
@@@ 
@@@

來源

2014-09-26 20:08:55 Mohannd

爲什麼char值在輸出期間轉換？

回答

相關問題