题目和另一种解法.txt

thinking in java 第三版 第五章 11题 答案

.  Following the form of the example Lunch.java, create a class called ConnectionManager that manages a fixed array of Connection objects. The client programmer must not be able to explicitly create Connection objects, but can only get them via a static method in ConnectionManager. When the ConnectionManager runs out of objects, it returns a null reference. Test the classes in main(?). 

class Connection{
    private Connection(){}
    public static Connection Make(){
        return new Connection();
    }
}
public class ConnectionManager{
    public static Connection[] func() {
     Connection[] n1={Connection.Make(),Connection.Make(),Connection.Make()};
     return n1;
    }
    public static void main(String[] args){
     System.out.print("the length of the array is:");
     System.out.println(func().length);
     System.out.println("a fixed array of Connection objects is created");
}
}