Java How To Program, Late Objects, 11th Edition

... | (++age >= 65)

guarantees that the condition ++age >= 65 will be evaluated. Thus, the variable age is incremented, regardless of whether the overall expression is true or false.

Error-Prevention Tip 4.11

For clarity, avoid expressions with side effects (such as assignments) in conditions. They can make code harder to understand and can lead to subtle logic errors.

Error-Prevention Tip 4.12

Assignment (=) expressions generally should not be used in conditions. Every condition must result in a boolean value; otherwise, a compilation error occurs. ...