How to have two constructors with same number of arguments but for different variables in java [closed]

Question

In my case, The class will have two constructors both taking 3 strings as arguments but one of the string variables that is to be initialized in one of the constructors may differ. Is it possible to implement the following:

class A {
   String x = null;
   String y = null;
   String z = null;
   String a = null;

   A(String x, String y, String z) {
      ....
   }

   A(String a, String y, String z) {
      ....
   }
}

Answer 1

No, but a quick solution is to use static helpers:

class A {

  String x, y, z, a;

  /** Constructor. Protected. See static helpers for object creation */
  protected A(String x, String y, String z, String a) {
    this.x = x;
    this.y = y;
    this.z = z;
    this.a = a;
  }

  /** Construct a new A with an x, y, and z */
  public static A fromXYZ(String x, String y, String z) {
    return new A(x, y, z, null);
  }

  /** Construct a new A with an a, y, and z */
  public static A fromAYZ(String a, String y, String z) {
    return new A(a, null, y, z);
  }
}

Answer 2

Is it possible to implement the following

No.

Because the compiler has no built-in crystal ball in order to choose the appropriate constructor at compile time.

Please be aware of two points:

• The parameter names in the constructor signature are lost after compilation - they are pure human sugar. So they cannot be use to dispatch between both ctors.

• The parameter names have nothing to do with the field names. That both are usually the same is of no concern to the compiler.