JAVA 基础心得4

File P1.java package MyPackage; class P1{ void afancymethod(){         System.out.println("What a fancy method");     } } //File P2.java public class P2 extends P1{     public static void main(String argv[]){            P2 p2 = new P2();            p2.afancymethod();     } } 1) Both compile and P2 outputs "What a fancy method" when run 2) Neither will compile 3) Both compile but P2 has an error at run time 4) P1 compiles cleanly but P2 has an error at compile time

4   The package statement in P1.java is the equivalent of placing the file in a different directory to the file. P2.java and thus when the compiler tries to compile P2 an error occurs indicating that superclass P1 cannot be found.

 

 

 

 Which of the following statements about threading are true?

1) You can only obtain a mutually exclusive lock on methods in a class that extends Thread or implements runnable.
2) You can obtain a mutually exclusive lock on any object.
3) A thread can obtain a mutually exclusive lock on an object by calling a synchronized method of that object.
4) Thread scheduling algorithms are platform dependent.
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