java构造函数：这个（.）

为什么输出为“021”？为什么会有“0”和“1”（既然“i”得到“2”，为什么会变为“1”）

C（）

调用

C（1）

哪个调用

C（1,1）

• C（1,1）

  打印0（

  this.i

  的默认值）并将2（

  i+j

  ）赋值给

  this.i

• 然后

  C（1）

  打印2并将1分配给

  this.i

• 然后

  C（）

  打印1

---

我认为这有助于更好地理解：

public C(int i) {
    this(i, i);
    System.out.println("*"+this.i);
    this.i = i;
}

public C(int i, int j) {
    System.out.println("@"+this.i);
    this.i = i + j;
}

public C() {
    this(1);
    System.out.println("#"+i);
}

---

现在，您可以在调用C（）时获得这些方法的序列
在代码注释中，您现在可以理解您的问题了

public class C {
    protected int i;

    public C(int i) {
        this(i, i); // got to two parameter constructer and after the result print the next line
        System.out.print(" + second "+this.i); // print value of i which is come from C(int i, int j) = 2
        this.i = i; // set the value of i to 1
    }

    public C(int i, int j) {
        System.out.print("first "+this.i); // print the value of i (in this case 0 the default value)
        this.i = i + j; // set i to 2
    }

    public C() {
        this(1); // got to one parameter constructer and after the result print the next line
        System.out.print(" + Third is "+i); // print value of i which is come from C(int i) = 1
    }

    public static void main(String[] args) {
        C c = new C();
    }
}

我希望这能有所帮助

public class C {
    protected int i;

    public C(int i) {
        this(i, i); // got to two parameter constructer and after the result print the next line
        System.out.print(" + second "+this.i); // print value of i which is come from C(int i, int j) = 2
        this.i = i; // set the value of i to 1
    }

    public C(int i, int j) {
        System.out.print("first "+this.i); // print the value of i (in this case 0 the default value)
        this.i = i + j; // set i to 2
    }

    public C() {
        this(1); // got to one parameter constructer and after the result print the next line
        System.out.print(" + Third is "+i); // print value of i which is come from C(int i) = 1
    }

    public static void main(String[] args) {
        C c = new C();
    }
}