在 Java 中反转整数

本教程将演示如何在不使用数组的情况下在 Java 中反转整数。

在不使用数组的情况下反转整数时,我们需要遵循三个步骤。

  • 使用模 (%) 运算符查找整数的余数。
  • 将变量 reverse 乘以 10,然后将其与余数相加。
  • 将数字除以 10。

在 Java 中使用递归来反转整数

递归是使用模数和除法运算符反转整数的最简单方法。

例子:

import java.util.Scanner;
public class Reverse_Recursion{
    //Create a method to reverse a number using recursion
    public static void Recursion_reverse(int input_number){
        if (input_number < 10){
        //If the number is less then 10 then no need to reverse
            System.out.println(input_number);
            return;
        }
        else{
            System.out.print(input_number % 10);
            Recursion_reverse(input_number/10);
        }
    }
    public static void main(String args[]){
        System.out.print("Enter the Integer you want to Reverse: ");
        Scanner input_num = new Scanner(System.in);
        int input_number = input_num.nextInt();
        System.out.print("The reverse of the given number using recursion is: ");
        Recursion_reverse(input_number);
    }
}

输出:

Enter the Integer you want to Reverse: 1234567890
The reverse of the given number using recursion is: 0987654321

在 Java 中使用 while 循环反转整数

要使用 while 循环反转整数,我们必须遵循提到的所有三个步骤。

例子:

import java.util.Scanner;
public class Reverse_While{
    public static void main(String args[]){
        System.out.print("Enter the Integer you want to Reverse: ");
        Scanner input_num = new Scanner(System.in);
        int input_number = input_num.nextInt();
        int reverse_number = 0;
        while(input_number != 0){
            int remainder_number = input_number % 10;
            reverse_number = reverse_number * 10 + remainder_number;
            input_number = input_number/10;
        }
        System.out.println("The reverse of the given number using while loop is: " + reverse_number);
    }
}

输出:

Enter the Integer you want to Reverse: 123456789
The reverse of the given number using while loop is: 987654321

在 Java 中使用 for 循环反转整数

for 循环也类似于 while 循环反转整数。

这次让我们尝试反转一个负整数。

例子:

import java.util.Scanner;
public class Reverse_For{
    public static void main(String args[])  {
        System.out.print("Enter the Integer you want to Reverse: ");
        Scanner input_num = new Scanner(System.in);
        int input_number = input_num.nextInt();
        int reverse_number = 0;
        for( ;input_number != 0; input_number=input_number/10){
            int remainder_number = input_number % 10;
            reverse_number = reverse_number * 10 + remainder_number;
        }
        System.out.println("The reverse of the given number using while loop is: " + reverse_number);
    }
}
Enter the Integer you want to Reverse: -123456789
The reverse of the given number using while loop is: -987654321