编写代码模拟手机与SIM卡组合的关系

package SIM;

public class SIM {
long number;
SIM(long number){
this.number = number;
}
long getNumber() {
return number;
}

}
package SIM;

public class phone {
SIM sim;
void setSIM(SIM card) {
sim = card;
}
long lookNumber() {
return sim.getNumber();
}

}
package SIM;

public class shouji {
public static void main(String[] args) {
SIM simOne = new SIM(18375435060L);
phone mobile = new phone();
mobile.setSIM(simOne);
System.out.println("手机号码："+mobile.lookNumber());
SIM simTwo = new SIM(18375436050L);
mobile.setSIM(simTwo);
System.out.println("手机号码更换为:"+mobile.lookNumber());
}

}