increasing and decreasing in loop

[Lao Kinsuyi]

I want someone to explain when to use ++x, --x, ++y, --y in for loop with examples and codes.

Secondly, look at this code :

class Uber{
static int y = 2;
Uber(int x) {this(); y = y*2;}
Uber() {y++; }
}
class Minor extends Uber{
Minor() {super(y); y = y+3; }
public static void main (String[] args) {
new Minor();
System.out.println(y);
}}
The answer given in the book of Kathy and Bert is 9.But, i think the answer should be 7. Because,y = 2 and y*2 is 4. With increment of 3 plus 4 i.e y+3(3+4) =7

[marc weber]

Originally posted by Lao Kinsuyi:
...The answer given in the book of Kathy and Bert is 9.But, i think the answer should be 7. Because,y = 2...

But the first line of Uber(int) is this(), which calls Uber() to increment y to 3.

Try adding println statements to see what's happening...

class Uber {
  static int y = 2;
 
  Uber(int x) {
    this(); //calls Uber()
    System.out.println("In Uber(int), y is " + y + ". y = y * 2...");
    y = y * 2;
  }
 
  Uber() {
    System.out.println("In Uber(), y is " + y + ". Incrementing y...");
    y++;
  }
}
 
class Minor extends Uber {
  Minor() {
    super(y);
    System.out.println("In Minor(), y is " + y + ". y = y + 3...");
    y = y + 3;
  }
 
  public static void main (String[] args) {
    new Minor();
    System.out.println("End value: " + y);
  }
}