package是Java產生包路徑的關鍵字,且應放在程序的第一句;
同一個包中的類在引用時,不需要import語句,不同包引用時需要添加import語句,且需要改變類的權限和類中數據成員爲public類型;
//該類在包 RunFighterPlane中
package RunFighterPlane;
class FighterPlane
{ String name;
int missileNum;
void fire(){
if (missileNum>0){
System.out.println("now fire a missile !");
missileNum -= 1;
}
else{
System.out.println("No missile left !");
}
}
}
//該類在包 RunFighterPlane中
package RunFighterPlane;
public class RunPlane
{
public static void main(String args[]){
FighterPlane fp = new FighterPlane();
fp.name = "蘇35";
fp.missileNum = 6;
fp.fire();
}
}//該類在包Resource中
package Resource;
public class FighterPlane
{
public String name;
public int missileNum;
public void fire(){
if (missileNum>0){
System.out.println("now fire a missile !");
missileNum -= 1;
}
else{
System.out.println("No missile left !");
}
}
}//該類在包run中
package run;
import Resource.*;
public class RunPlane
{
public static void main(String args[]){
FighterPlane fp = new FighterPlane();
fp.name = "蘇35";
fp.missileNum = 6;
fp.fire();
}
}
類處於包的情況如下圖:
運行結果: