Question

In Java, unlike in C++, we can provide an initial value for a field in its declaration:

public class BedAndBreakfast {

    public int capacity = 10;  //initialize to 10

    private boolean full = false;  //initialize to false
}

Why was there a need to allow this while it can be done more clearly in a constructor?

Answer 1

It is clearer if you define the default value with the property. If you have multiple constructors, you will have to define the values in each constructor, which is ugly.

Ultimately, the compiler puts these values in each constructor, so the net result is the same. It’s just more readable and easy to support this way.

Update: As BalusC noted in his comment, you can use an initializer block, which is again appended to each constructor by the compiler:

{ 
  var1 = 10;
  var2 = false;
}