java基础(八)之函数的复写/重写(override)

复写的意思就是子类对父类的修改。

复写的条件：

1、在具有父子类关系的两个类当中；
2、父类和子类各有一个函数，这两个函数的定义保持一致(返回值类型、函数名、参数列表)

还是老样子，3个文件来说明。

　

Person.java：

class Person{
	String name;
	int age;
	Person(){

	}
	void introduce(){
		System.out.println("My name is "+this.name +". My age is " +this.age);

	}
}

　　

Student.java：

class Student extends Person{
	String address;

	void introduce(){
		System.out.println("My name is "+super.name +". My age is " +super.age +". My home in " +this.address);
	}
}

　　

Test.java：

public class Test{
	public static void main(String[] args){
		Student li = new Student();
		li.name = "liming";
		li.age = 18;
		li.address = "china";
		li.introduce();

		Person zhang = new Person();
		zhang.name = "zhangsan";
		zhang.age = 20;
		zhang.introduce();
	}
}

　　

输出结果：

PS C:\Users\admin\Desktop\java_code\练习七> java Test
My name is liming. My age is 18. My home in china
My name is zhangsan. My age is 20
PS C:\Users\admin\Desktop\java_code\练习七>

　　

super调用父类函数

修改Person.java：

class Student extends Person{
	String address;

	void introduce(){
		super.introduce();
		System.out.println("My name is "+super.name +". My age is " +super.age +". My home in " +this.address);
	}
}

　　

修改Test.java:

public class Test{
	public static void main(String[] args){
		Student li = new Student();
		li.name = "liming";
		li.age = 18;
		li.address = "china";
		li.introduce();
	}
}

　　

输出结果：

PS C:\Users\admin\Desktop\java_code\练习七> java Test
My name is liming. My age is 18
My name is liming. My age is 18. My home in china