從方法返回布爾值

Question

我的程序應該檢查一個整數是否在一個隨機整數中。它會返回true或false。例如：45903包含4：true。因爲某些原因;我輸入數字後，我的代碼仍在運行。有些事情是我的containsDigit（）方法錯了，但我似乎無法弄清楚。我對布爾非常新。

import java.util.Scanner; 
import java.util.*; 

public class checkNum { 


public static void main(String[] args) { 

    // Create a new Scanner object 
    Scanner console = new Scanner(System.in); 
    // Create a new Random objects 
Random rand = new Random(); 

    // Declare a integer value that is getting the value in the range of[10000, 99999] 
    int randomNum = rand.nextInt(90000)+10000; 

    // Show the random value to user by using of System.out.println 
System.out.println(randomNum); 

    // Type a prompt message as "Enter a digit" 
System.out.println("Enter a digit: "); 

    // Assign user input to integer value 
    int digit = console.nextInt(); 

    // Define a boolean value that is assigned by calling the method "containDigit(12345,5)" 

    // Show the output 
    System.out.println(randomNum+ " contains" + 
        digit+" " + containDigit(randomNum,digit)); 

} 

public static boolean containDigit(int first, int second) { 
    int digi = 10000; 

    // Define all statements to check digits of "first" 
    while (first > 0) { 
    digi = first % 10; 
    digi = first/10; 
} 

    if (digi == second){ 
    return true; 
    }else { 
    return false; 
    } 
    // If it has "second" value in these digits, return true, 
    // If not, return false 

    // return a boolean value such as "return false"; 
    return false; 
} 

} 

Answer 1

我不明白你爲什麼要指定first %10到digi，然後立即用first/10覆蓋digi。

while循環可能永遠不會退出的first可能總是大於0。這可能永遠不會被輸入爲first可能等於0您可能要做到這一點：

while (first/10 == 0) { 
    first = first % 10; 
    if (first == second) 
     return true; 
    } 
    if(first%10 == second) 
    return true; 

return false; 

Answer 2

while循環永遠不會退出：

while (first > 0) { 
    digi = first % 10; 
    first = first/10; // i believe this should be first instead of digit   
} 

您應該添加一個簡單print語句來檢查你的digit和first變量的值是：

System.out.println("digi: "+digi); 
System.out.println("first: "+first); 

Answer 3

如果你不限於解決方法，我可以在下面建議：

return (randomInt + "").contains(digit + "");