为Animal类加一个字段 weight 动物的体重
public int weight;
为了能访问值,当然是public. public , 会带来可怕的后果
myFarm.goat.weight = 100 ; myFarm.goat.weight = - 100 ;
羊羊的体重 100 直接变到-100 -100都行?! 这是不能接受的! 将weight改为private
为了对weight值访问,加入两个方法.
public void setWeight( int w) { if (w > 0 ) { weight = w; } } public int getWeight() { return weight; }
在setWeight方法中,体重必须是>0 才有效.
这样,太麻烦咯.这时,应该用"属性"
private int weight; public int Weight { get { return weight;} set { if (value > 0 ) weight = value; } }
属性的使用
myFarm.goat.Weight = 100 ; // set value =100 Console.WriteLine(myFarm.goat.Weight); // get