Java Operators

 

The Java expression int idx = (int)(Math.random()*101) - 50; generates a random integer within the range of -50 to +50. Here's how it works step by step:

1. Math.random() generates a random floating-point number between 0.0 (inclusive) and 1.0 (exclusive). So, the value produced by Math.random() will always lie in the range [0.0, 1.0).

2. Math.random() * 101 multiplies the random number by 101. This means the result will be a random floating-point number in the range [0.0, 101.0). So, the number will be between 0 (inclusive) and just below 101 (exclusive).

3. Casting to int: The (int) casting operator truncates the decimal part, effectively rounding down the value to the nearest integer. So, for example, if Math.random() produces a value of 0.99, then Math.random() * 101 results in 99.99, and casting it to an int gives 99.

4. Subtracting 50: Finally, subtracting 50 from the integer result shifts the range of values. If the random number after casting lies between 0 and 100, subtracting 50 will shift the range to be between -50 and +50.

Range of Values:

• The smallest value Math.random() can produce is 0, which will give 0 * 101 = 0, and subtracting 50 results in -50.

• The largest value Math.random() can produce is just below 1.0, which will give 1 * 101 = 101, and subtracting 50 results in +51. However, since we're truncating the value when casting to int, the maximum value after the cast will be 100, and after subtracting 50, the result will be 50.

So, the possible values for idx will range from:

• Minimum: -50 (if Math.random() generates 0)

• Maximum: 50 (if Math.random() generates a value just below 1)

Thus, the output lies in the range from -50 to +50 inclusive.

Example:

• If Math.random() returns 0.25, then 0.25 * 101 = 25.25, and after casting to int, you get 25. Subtracting 50 gives 25 - 50 = -25.

• If Math.random() returns 0.75, then 0.75 * 101 = 75.75, and after casting to int, you get 75. Subtracting 50 gives 75 - 50 = 25