Do you confident about primitive types and arithmetic operators in Java? (+, -, *, /, %, ++, --)

Let's go through some examples!

Example 1: What do you think about the following code? (True or false)

      short s1 = 10; 
      short s2 = 11;
      short s3 = s1 + s2;

The answer is false. There will be a compilation error on line 3. Types as "byte", "short", and "char" are automatically promoted to "int" when used in expressions. So, the result of the "s1 + s2" expression is of type "int".

To resolve this, you have two options:

Change the type of s3 from "short" to "int":

        int s3 = s1 + s2;

Cast the result to "short" before assigning to s3:

        short s3 = (short) (s1 + s2);

Example 2: What do you think about this statement? (True or false)

    float a = 123.456;

The answer is false. This will result in a compilation error because in Java, a floating-point number like "123.456" is considered a "double" type by default.

To fix this, either add the 'f' suffix or change the variable type:

       // Using the 'f' suffix
        float a = 123.456f;
        // Alternatively, change the type to double
        double a = 123.456;

Example 3: How about this statement? (True or false)

    double d1 = 12.5;
    float f1 = 12.5f;
    float result = (float) (d1 + f1);

This will result in a compilation error on line 3. When performing arithmetic operations, Java automatically promotes types to the larger one. You have three solutions:

Cast d1 to "float" before addition:

        float result = (float) d1 + f1;

Cast the result to "float" after addition:

        float result = (float) (d1 + f1);

Change the result type to "double":

        double result = d1 + f1; // Recommended

Note: For "long" type, use 'l' or 'L' suffix to specify the value.

Example 4: What is the result of this statement?

    short s = (short) 1921222;
    System.out.println(s);

The result printed is 20678 = 1921222 % (2^16/2).

Example 5: What is the result of this statement?

    System.out.println((2147483647 + 1));
    // Note: 2^32/2-1 = 2147483647

The printed result is "-2147483648". When values exceed the range of "int", they wrap around.

Example 6 (last): What are the results of the following code?

    // 1.
    long x = 10;
    int y = 5;
    y = (int) (x * y);

    // 2.
    long x = 10;
    int y = 5;
    y *= x;

The first statement results in a compilation error on line 3. To fix it, cast the result explicitly.

The second statement works fine because of implicit type casting