java 面向对象

1.this :

2.构造器：

3.static:


package jiHeStudy;
 
public class Test03 {
 
 
    public static void main(String[] args) {
        //类变量只有一个
        Student stu = new Student();
        //对象.出类变量可赋值，不推荐
        stu.userName = "wwx";
        System.out.println(stu.userName);
        Student stu1 = new Student();
        //第二次对象.点出类变量赋值，会覆盖之前的赋值
 
        stu1.userName = "lr";
        System.out.println(stu.userName);
    }
 
 
}

4.类方法设计工具类（静态方法）：

5.类方法，实例方法的注意事项：

6.代码块：

7.单例类：

8.权限修饰符：

9.继承注意事项

10重写：

11.子类访问其他成员变量：

12.子类构造器的特点：

13.子类构造器应用：


package jiHeStudy;
 
public class Test03 {
 
 
    public static void main(String[] args) {
 
        Teacher t = new Teacher("lishi",11,"java");
        System.out.println(t);
    }
 
 
}
 
class Teacher extends People {
 
    String skill;
 
 
    public Teacher(String name,int age,String skill) {
        super(name,age);
        this.skill = skill;
    }
 
    @Override
    public String toString() {
        return "Teacher{" +
                "skill='" + skill + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
 
class People {
    String name;
    int age;
 
    public People() {
    }
 
    public People(String name, int age) {
        this.name = name;
        this.age = age;
    }
 
 
}

13.this(参数)调用兄弟构造器：

14.什么是多态：


package duotai;
 
public class Test {
 
    public static void main(String[] args) {
       People p1= new Teacher();
        p1.run();
        System.out.println(p1.name);
        People p2= new Student();
        p2.run();
        System.out.println(p2.name);
    }
 
}
package duotai;
 
public class People {
String name="父类";
    void run(){
        System.out.println("跑步");
    }
}
package duotai;
 
public class Teacher extends People{
    String name="t";
    @Override
    void run() {
        System.out.println("老师跑");
    }
}
package duotai;
 
public class Student extends People{
    String name="s";
 
    @Override
    void run() {
        System.out.println("学生跑");
    }
}

15.多态好处：

16.final:

17.常量：

18.抽象类：

19.模板方法：


package duotai;
 
public class Test {
 
    public static void main(String[] args) {
        People p1 = new Teacher();
        p1.sing();
        System.out.println("-----------------------");
        People p2 = new Student();
        p2.sing();
    }
 
}
package duotai;
 
public abstract class People {
 
    //模板方法
  public final void sing(){
       System.out.println("开始唱歌");
 
       dosing();
 
       System.out.println("结束唱歌");
   }
   abstract void dosing();
}
package duotai;
 
public class Teacher extends People{
      //重写抽象方法
@Override
    void dosing() {
        System.out.println("老师们合唱");
    }
}
package duotai;
 
public class Student extends People{
    //重写抽象方法
@Override
    void dosing() {
        System.out.println("学生们合唱");
    }
}

20.接口：

21.内部类：

21.1 4种形式：

21.2创建格式：

21.3成员内部类访问其他成员的特点：

21.4总结：

21.5静态内部类：

21.6局部内部类：

21.7匿名内部类！！！：


package jiHeStudy;
 
import java.util.ArrayList;
import java.util.Scanner;
 
public class Tset02 {
/*
动态开辟集合
 */
    public static void main(String[] args) {
 
     //  Animal a= new Cat();
//        Cat a = new Cat();
//        a.cry();
        Animal a = new Animal() {
            @Override
            public void cry() {
                System.out.println("喵喵喵");
            }
        };
        a.cry();
 
 
    }
}
//class Cat extends Animal{
//    @Override
//    public void cry() {
//        System.out.println("喵喵喵");
//    }
//}
 
 
abstract class Animal{
 
    public abstract void cry();
 
}


package Inner;
 
public class Test {
    public static void main(String[] args) {
 
/*
new Swimming() {
        @Override
        public void swim() {
            System.out.println("猫游泳");
        }
    }
    这一串相当于一个猫的实例对象，可直接做方法的参数
 */
    goGame(new Swimming() {
        @Override
        public void swim() {
            System.out.println("猫游泳");
        }
    });
 
 
    }
    public static void goGame(Swimming s){
        System.out.println("开始比赛");
        s.swim();
    }
}
 
 interface Swimming {
    void swim();
}