第五周学习总结

一、static-静态常量

(一) 静态变量

public class Student{
private  String name;
private  int age;
private  String gender;
public   static StringteacherName;
publicStudent(){
publicStudent(String name, int age,String gender) {
this.name = name;
this.age =age;
thisgender = gender;
}
public void study(){
System.out.printin(name+“正在学习”)；
}
public void show(){
System.out.println(name+”，” + jage + "，” +gender);
}

}
public class StudentTest
public  static void main(String[] args) {
student.teacherNome ="阿邱老帅"；
//1.创建第一个学生对象
Students1 = new Student();
s1.setName(“张二")；
s1.setAge(23);
s1.setGender("男")；
s1.study();
s1.show();
Student s2 = new Student();
s2,setName("李川");
s2.setAge(24);
s2.setGender("");
s2.study();
s2.show();
}
}

 

(二)静态方法

public  classArrayUtil {
private ArrayUtil  () { }
public  static StrinE print (int[] arr)
stringBuilder sb = newStringBuilder();
sb.append("[")
for (int i= 0; i < arr.length;i++）{
if(i == arr.length -1){
sb,append(arr[i]);
}else{
sb.append(arr[i]).append(", ）；
}
}
sb.append("]")；
return sb.tostring();
}
public static double getAveraga(double[] arr){
double sum = 0;
for (int i = 0; i  < arr.length;i++)
sum=Sum + arr[i];
return sum /arr.length:
}
}
publlc class TestDemo{
public static void main(String[] args ) {
int[] arr1 =(1,2, 3, 4， S1;
String str =ArrayUtil.printArr(arr1);
System.out.println(str);
double[] arr2 = (1.5, 3.7, 4.9, 5.8, 6.6);
double avg =ArrayUtil.getAverage(arr2);
System.out.println(avg);
}
}

（三）、static 注意事项

二、继承

（一）、继承定义

（二）、Java继承的特点

(三)继承范围]

(四)成员变量访问特点

 

public static void main(String[] args){
Zi z = new zi();
z, show( );
class Fu {
String name = "Fu";
String hobby = "喝茶”
}
class Zi extends Fu {
String name ="Zi";
Stringgame =“吃鸡"；
public  vold show() {
//打印子类
//System,outpr 1n(name);//Zi
//System.out.print1n(this.name);
//System.out.print1n(super.name);
//打印父类
//System.out.println( hobby);
}
}

(五)访问成员方法特点

public class Test {
public statlc vold main(Stringl] args) {
Student s = new Student();
s.lunch();
}
class Person {
public void eat() {
System.out.println(吃米饭， 吃菜”);
}
public void drink() {
System.out.println("喝开水”);
}
class Student extends Person {
public void lunch(){
eat();
drink();
}
}
class Student extends Perso {
public void lunch() {
//先在本类中查看eat和drink方法，子类如果没有，就会调用从父中继承下来的eat和drink方法
this.eat();
this.drink();
//直接调父的
super.eat(); 
super.drink();
}

 

(七)继承中的构造方法

 

 

预计下周学习: 多态,抽象类