JAVA-day5

一、目的

• 学习代码块的作用和形式及如何使用。
• 掌握内部类的使用
• 学习继承和多态的使用
• demo小练习

二、技术及其使用

1.代码块

    {
        age=20;
        System.out.println("代码块 age="+age);
    }
    //静态代码块
    static {
    //    age=20;
        System.out.println("静态代码块");
    }

2.内部类的使用

//定义一个内部类 用于管理相对布局的具体布局属性
    public class LayoutParams{
        float leftMergin;
        float topMergin;
        float rightMergin;
        float bottomMergin;

        public LayoutParams(float leftMergin,float topMergin,float rightMergin,float bottomMergin){
            this.leftMergin=leftMergin;
            this.topMergin=topMergin;
            this.rightMergin=rightMergin;
            this.bottomMergin=bottomMergin;
        }
    }

3.继承

(1)父类

class Person1{
}

(2)子类

class Student extends Person1{
}

三、demo代码

public class Person2 {
    protected String name;
    protected int age;

    public Person2(String name,int age){
        this.name=name;
        this.age=age;
    }
    public void walk(){}
    public void eat(){}
}

class Gwy extends Person2{
    int salary;
    int count;
    public Gwy(String name,int age,int salary,int count){
        super(name,age);
        this.salary=salary;
        this.count=count;
    }
    @Override
    public void walk(){
        System.out.println("闲庭信步");
    }
    @Override
    public void eat(){
        System.out.println("大吃大喝");
    }


    public void gshow() {
        System.out.println( "Gwy{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", salary=" + salary +
                ", count=" + count +
                '}');
    }
}
class woker extends Person2{
    int salary;
    String tec;

    public woker(String name, int age,int salary,String tec) {
        super(name, age);
        this.salary=salary;
        this.tec=tec;
    }
    @Override
    public void walk(){
        System.out.println("快步走");
    }
    @Override
    public void eat(){
        System.out.println("省吃俭用");
    }


    public void wshow(){
       System.out.println("woker{" +
               "name='" + name + '\'' +
               ", age=" + age +
               ", salary=" + salary +
               ", tec='" + tec + '\'' +
               '}');
    }
}
class test{
    public static void main(String[] args){
        ArrayList<Person2> persons=new ArrayList<>();
        Person2 g1=new Gwy("小王",24,12500,16);
        Person2 g2=new Gwy("小江",23,11000,10);

        persons.add(g1);
        persons.add(g2);

        Person2 w1=new woker("jack",34,8500,"IOS开发");
        Person2 w2=new woker("rose",36,7600,"Android开发");

        persons.add(w1);
        persons.add(w1);

        for (Person2 p:persons){
            if (p instanceof Gwy) {
                Gwy g = (Gwy) p;
                g.gshow();
                g.walk();
                g.eat();
            }else {
                woker w = (woker) p;
                w.wshow();
                w.walk();
                w.eat();
            }
        }
    }
}

四、心得体会

JAVA对于我来说还是有点难啊，听的时候还好虽然也有很多地方不明白，但自己写的时候才是最糟糕的，感觉什么都不知道，无从下手。看东哥写一遍后再写的时候还是会卡顿，但第二遍的时候就好一些了，所以还是要多练。