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:
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static void test() throwsRuntimeException {
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try {
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System.out.print("test");
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throw new RuntimeException();
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}
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catch (Exception ex) { System.out.print("exception"); }
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}
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public static voidmain(String[] args) {
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try { test(); }
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catch (RuntimeException ex) {System.out.print("runtime "); }
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System.out.print("end");
- }
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:
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public class Plant {
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private String name;
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public Plant(String name) {this.name = name; }
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public String getName() { returnname; }
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}
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public class Tree extends Plant{
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public void growFruit() { }
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public void dropLeaves() { }
- }
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:
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class Line {
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public static class Point {}
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}
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class Triangle {
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// insert code here
- }
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:
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class Nav{
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public enum Direction { NORTH,SOUTH, EAST, WEST }
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}
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public class Sprite{
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// insert code here
- }
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)