这个调用方法的程序为什么大多分写两个类写？不太懂 下面是我变成一个类写的对么

public class telphone{

float screen;

float cpu;

float mem;

void call(){

System.out.println("telphone具有打电话的功能");

}

void sendMessage(){

System.out.println("screen"+screen+"cpu"+cpu+"mem"+mem+"telphone具有发短信的功能");

}

}

public class telphone{

public static void main(String[] args){

telphone phone=new telphone();

phone.screen=5.0f;

phone.cpu=1.5f;

phone.mem=2.0f;

phone.sendMessage();

phone.call();

}

}

public class telphone{

float screen;

float cpu;

float mem;

public static void main(String[] args){

telphone phone=new telphone();

phone.screen=5.0f;

phone.cpu=1.5f;

phone.mem=2.0f;

phone.sendMessage();

phone.call();

}

void call(){

System.out.println("telphone具有打电话的功能");

}

void sendMessage(){

System.out.println("screen"+screen+"cpu"+cpu+"mem"+mem+"telphone具有发短信的功能");

}

}