How do you swap two numbers in Java without using a temporary variable?

• A. By using a third variable
• B. By performing arithmetic operations
• C. By using an array
• D. By bitwise operations

Answer: (B)

Swapping two numbers in Java without using a temporary variable can indeed be accomplished through arithmetic operations. The basic idea is to use addition and subtraction to achieve the swap.

Here’s how it works:

1. Assign the sum of both numbers to one of the original variables. For example, if you have two integers, a and b, you can do a = a + b;.

2. Then, subtract the new value of a (which is the sum) by b and assign it to b. This operation effectively sets b to the original value of a because now b is essentially a + b - b, which simplifies to a.

3. Finally, subtract the new value of b from the new value of a to recover the original value of b and assign it to a.

Here's a simple example:

int a = 5;

int b = 10;

a = a + b; // Now a is 15

b = a - b; // Now b is 5 (original value of a)

a = a - b; // Now a is 10 (original value of b)