Java考试题之七
QUESTION 150
Click the Exhibit button. Given: ClassA a = new ClassA(); a.methodA(); What is the result?
A. Compilation fails.
B. ClassC is displayed.
C. The code runs with no output.
D. An exception is thrown at runtime.
Answer: D
问题出在第24行，classC还没有new一个，就直接用函数getValue()，NullPointerException会被抛出
public ClassC classC;该行代码没有new出来ClassC,空指针异常；
QUESTION 151 Given:
11. static void test() throwsRuntimeException {
12. try {
13. System.out.print("test");
14. throw new RuntimeException();
15. }
16. catch (Exception ex) { System.out.print("exception"); }
17. }
18. public static voidmain(String[] args) {
19. try { test(); }
20. catch (RuntimeException ex) {System.out.print("runtime "); }
21. System.out.print("end");
22. }
What is the result?
A. test end
B. Compilation fails.
C. test runtime end
D. test exception end
E. A Throwable is thrown by mainat runtime.
Answer: D
QUESTION 152 Given:
1. public class Plant {
2. private String name;
3. public Plant(String name) {this.name = name; }
4. public String getName() { returnname; }
5. }
1. public class Tree extends Plant{
2. public void growFruit() { }
3. public void dropLeaves() { }
4. }
Which statement is true?
A. The code will compile withoutchanges.
B. The code will compile if publicTree() { Plant(); } is added to the Tree class.
C. The code will compile if publicPlant() { Tree(); } is added to the Plant class.
D. The code willcompile if public Plant() { this("fern"); } is added to the Plantclass.
E. The code will compile if publicPlant() { Plant("fern"); } is added to the Plant class.
Answer: D
Section: (none)
Plant需要一个无参默认构造函数，因为子类带一个参数的构造函数
QUESTION 153
Given:
10. class Line {
11. public static class Point {}
12. }
13.
14. class Triangle {
15. // insert code here
16. }
Which code, inserted at line 15, createsan instance of the Point class defined in Line?
A. Point p = new Point();
B. Line.Point p = newLine.Point();
C. The Point class cannot beinstatiated at line 15.
D. Line l = new Line() ; l.Point p= new l.Point();
Answer: B
QUESTION 154 Given:
10. class Nav{
11. public enum Direction { NORTH,SOUTH, EAST, WEST }
12. }
13. public class Sprite{
14. // insert code here
15. }
Which code, inserted at line 14, allowsthe Sprite class to compile?
A. Direction d = NORTH;
B. Nav.Direction d = NORTH;
C. Direction d = Direction.NORTH;
D. Nav.Direction d = Nav.Direction.NORTH;
Answer: D
Section: (none)
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