Doubt about toString Java method

Question

I would like to know the difference between using and not using the method toString in Java, because I understood that it serves as a print normal. Has some advantage in using this method ?

My question basically is between using for example:

System.out.println(product.name + product.price + product.add);

and between using the toString to print this on the screen.

Answer 1

Sasaki you are quite wrong about using the method toString. To print something on the console you must use the method print as you yourself did in the code of your question.

The method toString is a method that all classes have in Java ( since they all inherit from Object ) and serves only for return a String and nay print it. See an example below for you to better understand:

public class Exemplo {
    public static void main(String[] args) {

        Integer num = 17;
        System.out.println(num.toString().getClass());
    }
}

The exit code above will be java.lang.String because by calling the method toString he returned a String from the Integer object.

The advantage of using this method is that we can "convert" any object to String. Including, the method itself print prints any kind of value because it calls the method internally toString.

See this other example where I overwrite the method in the class Usuario to print the formatted object attributes:

class Usuario {

    private String nome = "Bruno";
    private int idade = 29;

    public String toString(){
        return "Nome = " + this.nome + " Idade = " + this.idade;
    }
}

public class Exemplo{
    public static void main(String[] args) {

        Usuario usuario = new Usuario();

        System.out.println(usuario);
    }
}