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

Using this(args). The preferred pattern is to work from the smallest constructor to the largest.

public class Cons {

    public Cons() {
        // A no arguments constructor that sends default values to the largest
        this(madeUpArg1Value,madeUpArg2Value,madeUpArg3Value);
    }

    public Cons(int arg1, int arg2) {
       // An example of a partial constructor that uses the passed in arguments
        // and sends a hidden default value to the largest
        this(arg1,arg2, madeUpArg3Value);
    }

    // Largest constructor that does the work
    public Cons(int arg1, int arg2, int arg3) {
        this.arg1 = arg1;
        this.arg2 = arg2;
        this.arg3 = arg3;
    }
}

You can also use a more recently advocated approach of valueOf or just "of":

public class Cons {
    public static Cons newCons(int arg1,...) {
        // This function is commonly called valueOf, like Integer.valueOf(..)
        // More recently called "of", like EnumSet.of(..)
        Cons c = new Cons(...);
        c.setArg1(....);
        return c;
    }
} 

To call a super class, use super(someValue). The call to super must be the first call in the constructor or you will get a compiler error.