Java 考试题2.docVIP

Part 1: Single-choice questions（20 points） 1、Which keyword is used to allow interaction with the lock flag? A. native B. static C. synchronized D. abstract 2、Given the following fragment of code: Double d1 = new Double(1.0); Double d2 = new Double(1.0); Float f = new Float(1.0F); Which results of the following expressions are true? A. d1 == d2 B. d1.equals(d2) C. d1 = f D. f.equals(d1) 3. What would be the result of attempting to compile and run the following piece of code? public class Test { public static void main(String args[]){ int x; System.out.println(Value is + x); } } A. The output Value is 0 is printed. B. An object of type NullPointerException is thrown. C. An illegal array declaration syntax compiler error occurs. D. A possible reference before assignment compiler error occurs. 4. A design pattern is typically used to A. allow the use of object-orientated concepts in a language that is not object-oriented B. describe a practical solution to a common design problem C. ensure that code executes at optimal speed during runtime D. reduce the number of classes in the design of a program 5.import java.io.*; public class Ppvg{ public static void main(String argv[]){ Ppvg p = new Ppvg(); p.fliton(); } public int fliton(){ try{ FileInputStream din = new FileInputStream(Ppvg.java); din.read(); }catch(IOException ioe){ System.out.println(flytwick); return 99; }finally{ System.out.println(fliton); } return -1; } } Assuming the file Ppvg.java is available to be read which of the following statements are true if you try to compile and run the program? A.The program will run and output only flytwick B. The program will run and output only fliton C. The program will run and output both fliton and flytwick D. An error will occur at compile time because the method fliton attempts to return two values 6. In Java, the default layout manager for a JPanel component is A. GridLayout B. BorderLayout C. GridBagLayou