首页 > 代码库 > java与继承相关一些点

java与继承相关一些点

子类继承自基类,当子类的构造器被调用时会默认调用基类的无参数构造器,如果基类没有无参数构造器,则子类必须调用super(参数...)来调用基类的有参数构造器,否则会报错。

package com.company;import java.util.ArrayList;import com.yeyingqi.Printer;import static com.yeyingqi.Printer.*;class Animal{    public String name;    public String type;    public Animal(String type){        this.type = type;        Println("Animal Construtor with argc");    }    public Animal(){        Println("Animal Construtor");    }}class Dog extends Animal{    private int age;    public Dog(String type) {        super(type);        Println("Dog Construtor with argc");    }    public Dog(){        Println("Dog Construtor");    }    public void speak(){        Println(name);    }}public class Main {    public static void main(String[] args) {    // write your code here        Dog dog = new Dog("zjl");        Dog dog1 = new Dog();    }}

结果:

Animal Construtor with argc
Dog Construtor with argcAnimal ConstrutorDog ConstrutorProcess finished with exit code
0

 

java与继承相关一些点