Question

I know I can call static methods inside a constructor.

1. I have one contructor in one class which is calling another constructor through this(arguments).

2. Secondly that second constructor is calling super(arguments) calling super constructor.

I want to execute some code before these constructors execute. I cannot use a static block. Any ideas?

Answer 1

You can call static methods. I often do it like this:

public class MyClass extends SuperDuperClass {

  public MyClass() {
    this(convert("Foo!"));  // convert will be executed 
                            // other constructor is called
  }

  public MyClass(String arg) {
    super(convert(arg));  // convert will be executed 
                          // before superconstructor is called
  }

  private static String convert(String arg) {
    return arg + "_modified";
  }
}

Of course, we can’t call instance methods or use non static fields.

(and, of course, this pattern requires a constructor on super that takes parameters)