package cn.itcast.day09.demo01;

public class Student {
    private String name;
    private int age;
    static String room;
    private int id;
    private static int idCounter = 0; / / student number counter, each new new object count++
    public Student(){
        this.id = ++idCounter;
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
        this.id = ++idCounter;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

package cn.itcast.day09.demo01;
/* If the member variable uses the static keyword, then the variable belongs to the class */
public class Demo01StaticField {
    public static void main(String[] args) {
        Student one = new Student("gj",20);
        one.room = "101";
        System.out.println("name:"+one.getName()+"   age:"+one.getAge()+"    room:"+one.room);
        System.out.println("id is:"+one.getId());
        Student two = new Student("hr",21);
        System.out.println("name:"+two.getName()+"   age:"+two.getAge()+"    room:"+one.room);//static decoration, all class sharing
        System.out.println("id is:"+two.getId());
    }



}

package cn.itcast.day09.demo01;
The /*static modifier member method becomes a static method, does not belong to an object, and belongs to a class.
 * No static modification must first create an object to use
 * Static can not access non-static: in memory, existing static content has non-static content
 * Static methods cannot use this*/
public class Demo02StaticMethod {
    public static void main(String[] args) {
        MyClass obj = new MyClass();
        obj.method();/ / Create an object before you can use
        / / Static methods can be called with the object name, can also be called directly by the class name
        obj.methodStatic();/ / Not recommended, will be translated into class name by javac after compilation. Static method name
        MyClass.methodStatic();
        myMethod();/ / Direct call
    }
    public static void myMethod(){
        System.out.println("Own method");   / / Static methods in this class can omit the name
    }
}

package cn.itcast.day09.demo01;

public class MyClass {
    public void method(){
        System.out.println("This is a member method");
    }
    public static void methodStatic(){
        System.out.println("This is a static method");
    }
}

package cn.itcast.day09.demo01;
/* static code block */
public class Person {
    static {
        System.out.println("Static method is called");/ / The first time you use this class, the static method call is only one time
    }
    public Person(){
        System.out.println("Construction Method Execution");
    }
}

package cn.itcast.day09.demo01;
/* static method assigns static variables at once */
public class Demo03Static {
    public static void main(String[] args) {
        Person one = new Person();// static content first
        Person twp = new Person();/ / Static method is no longer executed
    }
}