面向对象
package com.andy.base.oop.demo01;
public class Demo01 {
//main方法
public static void main(String[] args) {
}
/*
修饰符 返回类型 方法名(...){
//方法体
return 返回值;
}
*/
//return 结束方, 返回一个结果!
public String sayHello(){
return "hello,world";//方法结束
}
public int max(int a ,int b){
return a>b?a:b;
}
}
package com.andy.base.oop.demo01;
public class Demo02 {
public static void main(String[] args) {
//实例化这个类 new
//对象类型 对象名 = 对象值;
Student student = new Student();
student.say();
}
//和类一起加载的
public static void a(){
//b();
}
//类实例化之后才存在
public void b(){
}
}
package com.andy.base.oop.demo01;
public class Demo03 {
public static void main(String[] args) {
int add = Demo03.add(1, 2);
System.out.println(add);
}
public static int add(int a ,int b ){
return a+b;
}
}
package com.andy.base.oop.demo01;
//值传递
public class Demo04 {
public static void main(String[] args) {
int a = 1;
System.out.println(a);//1
Demo04.change(a);
System.out.println(a);//1
}
//返回值为空
public static void change(int a ){
a = 10;
}
}
package com.andy.base.oop.demo01;
//引用传递 对象,本质还是值传递
public class Demo05 {
public static void main(String[] args) {
Person person = new Person();
System.out.println(person.name);//null
Demo05.change(person);
System.out.println(person.name);//钟健
}
public static void change(Person person ){
//person是一个对象:指向的--->Person person = new Person();这是一个具体的人,可以改变属性!
person.name = "钟健";
}
}
class Person{
String name;//null
}
package com.andy.base.oop.demo01;
//引用传递 对象,本质还是值传递
public class Demo05 {
public static void main(String[] args) {
Person person = new Person();
System.out.println(person.name);//null
Demo05.change(person);
System.out.println(person.name);//钟健
}
public static void change(Person person ){
//person是一个对象:指向的--->Person person = new Person();这是一个具体的人,可以改变属性!
person.name = "钟健";
}
}
class Person{
String name;//null
}
package com.andy.base.oop.demo01;
//学生类
public class Student {
//非静态方法
public void say(){
System.out.println("学生说话了");
}
}
Demo02
package com.andy.base.oop.demo01.demo02;
//学生类
public class Student {
//属性:字段
String name;
int age;
//方法
public void study(){
System.out.println(this.name+"在学习");
}
}
package com.andy.base.oop.demo01.demo02;
//一个项目应该只能有一个main方法
public class Application {
public static void main(String[] args) {
//类:是抽象的 ,要实例化
//类实例化后会返回一个自己的对象!
//student对象就是一个Student类的具体实例!
Student xiaoming = new Student();
Student xh = new Student();
xiaoming.name = "小明";
xiaoming.age = 3;
System.out.println(xiaoming.name);
System.out.println(xiaoming.age);
xh.name = "小红";
xh.age = 3;
System.out.println(xh.name);
System.out.println(xh.age);
//System.out.println(xiaoming.name);
}
}