Revisión de clases y objetos de Java

package ObjectStudy;

public class Phone {
    
    
    String brand;
    double price;
    public void call(String who){
    
    
        System.out.println("给"+who+"打电话！");
    }
    public void sentMessage(){
    
    
        System.out.println("群发短信");
    }
}

//-------------------------------
package ObjectStudy;
public class Phonetest {
    
    
    public static void main(String[] args) {
    
    
    Phone pho=new Phone();
        System.out.println(pho.brand);
        System.out.println(pho.price);
        pho.brand="red";
        pho.price=100;
        pho.call("张三");
        pho.sentMessage();
    }
}