How do I call one constructor from another in Java?

Question

Is it possible to call a constructor from another (within the same class, not from a subclass)? If yes how? And what could be the best way to call another constructor (if th

Answer 1

[Note: I just want to add one aspect, which I did not see in the other answers: how to overcome limitations of the requirement that this() has to be on the first line).]

In Java another constructor of the same class can be called from a constructor via this(). Note however that this has to be on the first line.

public class MyClass {

  public MyClass(double argument1, double argument2) {
    this(argument1, argument2, 0.0);
  }

  public MyClass(double argument1, double argument2, double argument3) {
    this.argument1 = argument1;
    this.argument2 = argument2;
    this.argument3 = argument3;
  }
}

That this has to appear on the first line looks like a big limitation, but you can construct the arguments of other constructors via static methods. For example:

public class MyClass {

  public MyClass(double argument1, double argument2) {
    this(argument1, argument2, getDefaultArg3(argument1, argument2));
  }

  public MyClass(double argument1, double argument2, double argument3) {
    this.argument1 = argument1;
    this.argument2 = argument2;
    this.argument3 = argument3;
  }

  private static double getDefaultArg3(double argument1, double argument2) {
    double argument3 = 0;

    // Calculate argument3 here if you like.

    return argument3;

  }

}