测试extends继续 java三大属性之一
测试override重写
测试final润色
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class Children{
String name;
int age ;
Children friend;
public void pn(){
System.out.println(name);
}
}
class Student1{
String name;
int age ;
Children friend;
public void pn(){
System.out.println(name);
}
//属性方法和Children同等
String major;
public void pm(){
System.out.println(major);
}
}
class Student2 extends Children{
//继续了Children类的所有内容 name age pn friend
public void pa(){
System.out.println(age);
//直接调用继续过来的的age
pn();
}
String major;
public Student2(String name,int age,String major){
this.name = name;
this.age = age;
this.major = major;
}
public class TestExtends {
public static void main(String[] args) {
Student2 s1 = new Student2("a",10,"Math");
System.out.println(s1 instanceof Student2);
//instanceof运算符 判断工具s1是否属于类Student2
System.out.println(s1 instanceof Children);
//判断s1是否属于父类Children 结果true
Student1 s2 = new Student1();
System.out.println(s2 instanceof Student1);
//System.out.println(s2 instanceof Children);报错 结果false
}
}
}
class Student3{
//不写明extends 默认 Student3 extends java.lang.Object
}
class Student4 extends Children{
Student4 friend;
//重写override 把Children类里的friend属性重定义，父类原始属性不受影响
//重写的范围小于即是父类的原型 父类的friend是Children型 子类是Student4小于即是Children
short age;
//父类age是int 子类age是short小于即是int
public void pn(){
System.out.println("The name is "+name);
}
//对原方法重写 变动内容
}
final class Student5 extends Children{
//final润色的类不能再往下继续 常见String Math类都是final
final int age =10;
//继续的属性可以final 不可再修正 不影响父类age
final public void pn(){
System.out.println(""+name+age);
}
//final的方法不可重写 可以重载overload
}
