java关于构造函数和boolean的问题

Question

public class WuMingFen {
    String theMa = "酸辣";
    int quantity = 2;
    boolean soup = false;

    public WuMingFen() {
        soup = true;
}
    public WuMingFen (String theMa, int quantity, boolean soup){
        this.theMa = theMa;
        this.quantity = quantity;
        this.soup= soup;
    }
    public WuMingFen (String theMa, int quantity){
        this.theMa = theMa;
        this.quantity = quantity;
    }

    public void check(){
        System.out.println("面码："+ theMa +"，粉的份量："+ quantity +"两，是否带汤："+ soup);
    }
}

为什么有下面这个构造函数？

public WuMingFen() {
soup = true;
}

Answer 1

为了你调用他们的时候，soup的默认值不一样而已。比如你在测试类中定义一个有参构造和一个无参构造：

WuMingFen wmf=new WuMingFen(); //无参构造的soup默认值为：soup=true;

WuMingFen wmf=new WuMingFen(“酸辣”, 2, false); //有参构造的soup从这里传值