没有默认构造函数的Java类

Question

I know if default constructor isn't declared and my class don't have any other constructor Java generates a default constructor for me automatically. If I declare some constructor, I need declare the default constructor manually.

Why is this case lac4 contains default values in attributes which not have been initilized in constructor and I don't have default constructor ("ataque", "vidaAtual" and "vidaMaxima" contains 0)? I know that Java initializes attributes with default values but for my this occurs only in the default constructor.

public class CartaLacaio {

    private int ID;
    private String nome;
    private int ataque;
    private int vidaAtual;
    private int vidaMaxima;
    private int custoMana;

    public CartaLacaio(int ID, String nome, int ataque, int vida, int mana) {
        this.ID = ID;
        this.nome = nome;
        this.ataque = ataque;
        this.vidaAtual = vida;
        this.vidaMaxima = vida;
        this.custoMana = mana;
    }

    public CartaLacaio(int ID, String nome, int custoMana){
        this.ID = ID;
        this.nome = nome;
        this.custoMana = custoMana;
    }

    public CartaLacaio(CartaLacaio origem){

    }

   //Getters and setters

}

My main

public static void main(String[] args) {
        CartaLacaio lac1 = new CartaLacaio(1, "Frodo Bolseiro", 2, 1, 1);
        CartaLacaio lac2 = new CartaLacaio(2, "Aragorn", 5, 7, 6);
        CartaLacaio lac3 = new CartaLacaio(3, "Legolas", 8, 4, 6);
        CartaLacaio lac4 = new CartaLacaio(4, "Teste nome", 3);
    }

Answer 1

...but for my this occurs only in the default constructor.

No, that happens when the instance is created, before any constructor is called.

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Just FWIW, if you had initializers on those fields, eg:

public class Example {
    private int a = 42;

    // ...
}

...the code to set those initializers would be inserted automatically into the beginning of every constructor in the class by the compiler.

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I know if default constructor isn't declared and my class don't have any other constructor Java generates a default constructor for me automatically. If I declare some constructor, I need declare the default constructor manually.

You're confusing two separate things.

The default constructor is the constructor the compiler will generate for you if you don't provide any constructors.

A zero-parameters constructor is a constructor that accepts no parameters.

The default constructor is a zero-parameters constructor. If you provide a zero-parameters constructor explicitly, it's not a default constructor. "Default" means just that: The default , if no other is provided.

Answer 2

You are wrong in your statement

I know that Java initializes attributes with default values but for my this occurs only in the default constructor.

Java automatically initializes attributes with default values also for overloaded constructor or a non-default constructor