java中这两个构造方法一个队，一个错？感觉没有区别啊？

Question

第一种：
public class point {
private double x;
private double y;
public point(){
this(0,0);
}
public point(double x, double y){
this.x = x;
this.y = y;
}
}
第二种
public class point {
private double x;
private double y;
public point(){
this.x = this.y = 0;
}
public point(double x, double y){
if(x > 0||y > 0){
this.x = x;
this.y = y;
}else{
this();
}
}

Answer 1

很简单，第二种写法有编译错误Constructor call must be the first statement in a constructor。
java语法归档，调用构造函数必须是第一条语句，你这样显然是不行的。