144 static关键字静态修饰成员变量

标题144 static关键字静态修饰成员变量

package Demo03;//144 static关键字静态修饰成员变量

public class Student {
private String name;
private int age;
static String room;
private int id;

private static int idCounter=0;//学号计数器
public Student(){
idCounter++;
}
public Student(String name,int age){
    this.name=name;
    this.age=age;
    this.id=++idCounter;
}

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

}

package Demo03;
/*

• 如果一个成员变量使用了static关键字，那么这个变量不再属于自己

• 而是属于所在的类，也就是多个对象共享一个数据

• */
  public class demo01StaticField {
  public static void main(String[] args) {

    Student one=new Student("郭靖",20);
    one.room="101教室";
    Student two=new Student("黄蓉",16);
    System.out.println("名前:"+one.getName()+"年齢:"+one.getAge()+"教室:"+one.room+"ID:"+one.getId());
    System.out.println("名前:"+two.getName()+"年齢:"+two.getAge()+"教室:"+two.room+"ID:"+two.getId());
  

  }

}