java类基础

class Person {
    private String name;
    private int age;
    
    {
        //构造代码块：可以给【所有】对象进行初始化的
        //放构造函数里的，共性初始化代码
    //执行顺序：1.静态代码块，2.构造代码块，3.构造函数
        System.out.println("Person run.");
    }
    
    static String country = "CN";
    
    public void speak() {

        System.out.println(name+":"+age);
        
    }
    
    Person() {
        name = "baby";
        age = 1;
    }
    
    Person(String n, int a) {
        age = a;
        name = n;
    }
    
    public void setName(String n) {
        name = n;
        
    }
}

class ConsDemo {
    public static void main (String[] args) {
        Person p = new Person();
        p.speak();
        
        Person p2 = new Person("旺财", 16);
        p2.setName("旺旺");
        p2.speak();
        
        System.out.println(Person.country);
        
        System.out.println(args);
        System.out.println(args.length);
        try {
            System.out.println(args[0]);
        } catch (Exception e) {
            System.out.println("log error:"+e);
        }
        
        StaticCode.show(); //静态类，类名进行方法调用
    }
    
}

class StaticCode {
    
    static int num;
    static { //静态代码块，进行类的初始化
        
        num = 10;
        System.out.println("Static init.");
    }
    
    static void show() {
        System.out.println(num);   
        
    }
}