Boolean type

In addition to arithmetic operations from school, we know operations of comparison. For example, 5 > 4. It sounds like the question: “5 is more than 4?”. In this case, the answer is “yes.” In other cases, the answer may be no (for example, for 3 < 1).

List of comparison operations:

  • < less
  • <= less or equal
  • > more
  • >= greater or equal
  • == equal
  • != not equal

The logical operation of the type 5 > 4 is an expression, and its result is the value of the logical type. The Java boolean type bool is a value that is written as true or false, for example, var isFivePositive = (5 > 0).

Let us try to write a function that takes the child’s age in years (integer is an int type) and determines whether the child is a baby. Infants are considered children up to a year:

static boolean isInfant(int age) {
  return age < 1;

We take advantage of the fact that any operation is an expression, therefore, with a single line of function, we write “return the value that will be obtained by comparing age < 1”.

Depending on the argument that came in, the comparison will be either true or false , and return will return this result.

Call the function and display the result.

public static void main(String[] args) {

static boolean isInfant(int age) {
  return age < 1;

And now let's check a child who is half a year old - zero full years:




Write the function isPensioner, which takes the age as the only argument and checks if this age is retirement. Pension is considered the age of 60 years and more.

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