Statement Control Java Tutorial

The do-while statement is like the while statement, except that the associated
block always gets executed at least once.
Its syntax is as follows:

do {
    statement (s)
} while (booleanExpression);
Just like the while statement, you can omit the braces if there is only one
statement within them. However, always use braces for the sake of clarity.

public class MainClass {
  public static void main(String[] args) {
    int i = 0;
    do {
      System.out.println(i);
      i++;
    } while (i < 3);
  }
}
This prints the following to the console:
0
1
2
The following do-while demonstrates that at least the code in the do block will be
executed once even though the initial value of j used to test the expression j

public class MainClass {
  public static void main(String[] args) {
    int j = 4;
    do {
        System.out.println(j);
        j++;
    } while (j < 3);
  }
}
This prints the following on the console.
4