继承

package incheir;

public class i3 extends i2{
    private String deparetment;
    private String specialiay;
    public i3()
    {
        super("hu",21);    //父类的构造函数必须在第一行；
        System.out.println("子类有构造方法！");

    }
}

package incheir;

public class i2 {
    public String name;
    public String sex;
    public int age;
    public i2()
    {
        System.out.println("父类无构造方法！");
    }
    public i2(String n,int a)
    {
        name=n;
        age=a;
        System.out.println("父类有构造方法！");
    }
    public void setName(String name) {
        this.name = name;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public String getSex() {
        return sex;
    }

    public int getAge() {
        return age;
    }
}

package incheir;

public class i1 {
    public static void main(String[] args) {
        i3 s=new i3();
    }
}