Object creation

class Point {
  int x;
  int y;
}

Is there any problem in this code? We can discuss it a lot, but the main issue is that Java creates constructor by default and by using

Point p = new Point();
p.x = 10;

This object is incomplete! since we encapsulated x and y in the class Point. We will have x = 10, y = 0, due to the fact Java has default values. And we will not be able to distinguish that from

Point p = new Point();
p.x = 10;
p.y = 0;

So, the solution is simple, just introduce a constructor

class Point {
  int x;
  int y;

  Point(int x, int y) {
    this.x = x;
    this.y = y;
  }
}

in case we have at least one constructor defined, Java will not create “default” constructor without parameters. and our code

Point p = new Point();

will stop compiling. Now the only valid code is

Point p = new Point(3, 5);