p.setWeight(420);
p.changePayload(420);
p = new Payload(420);
Payload.setWeight(420);
p = Payload.setWeight(420);
p = new Payload(); p.setWeight(420);
第1题:
1. package foo; 2. 3. import java.util.Vector; 4. 5. private class MyVector extends Vector { 6. int i = 1; 7. public MyVector() { 8. i = 2; 9. } 10. } 11. 12. public class MyNewVector extends MyVector { 13. public MyNewVector () { 14. i = 4; 15. } 16. public static void main (String args []) { 17. MyVector v = new MyNewVector(); 18. } 19. } The file MyNewVector.java is shown in the exhibit. What is the result?()
第2题:
11. class Animal { public String noise() { return “peep”; } } 12. class Dog extends Animal { 13. public String noise() { return “bark”; } 14. } 15. class Cat extends Animal { 16. public String noise() { return “meow”; } 17. } ..... 30. Animal animal = new Dog(); 31. Cat cat = (Cat)animal; 32. System.out.printIn(cat.noise()); What is the result?()
第3题:
11. public class Test { 12. public void foo() { 13. assert false; 14. assert false; 15. } 16. public void bar(){ 17. while(true){ 18. assert false; 19. } 20. assert false; 21. } 22. } What causes compilation to fail?()
第4题:
10. public class Foo implements java.io.Serializable { 11. private int x; 12. public int getX() { return x; } 12.publicFoo(int x){this.x=x; } 13. private void writeObject( ObjectOutputStream s) 14. throws IOException { 15. // insert code here 16. } 17. } Which code fragment, inserted at line 15, will allow Foo objects to be correctly serialized and deserialized?()
第5题:
1. class A { 3. public String to String() { 4. return “4”; 5. } 6. } 7. class B extends A { 8. public String toString() { 9. return super.toString() + “3”; 10. } 11. } 12. public class Test { 13. public static void main (String[] args) { 14. System.out.printIn(new B()); 15. } 16. } What is the result( )?
第6题:
10. public class Hello { 11. String title; 12. int value; 13. public Hello() { 14. title += “ World”; 15. } 16. public Hello(int value) { 17. this.value = value; 18. title = “Hello”; 19. Hello(); 20. } 21. } and: 30. Hello c = new Hello(5); 31. System.out.println(c.title); What is the result?()
第7题:
10. class Line { 11. public class Point { public int x,y; } 12. public Point getPoint() { return new Point(); } 13. } 14. class Triangle { 15. public Triangle() { 16. // insert code here 17. } 18. } Which code, inserted at line 16, correctly retrieves a local instance of a Point object?()
第8题:
4321
0000
An exception is thrown at runtime.
Compilation fails because of an error in line 18.
第9题:
Point p = Line.getPoint();
Line.Point p = Line.getPoint();
Point p = (new Line()).getPoint();
Line.Point p = (new Line()).getPoint();
第10题:
peep
bark
meow
Compilation fails.
An exception is thrown at runtime.
第11题:
Compilation will succeed.
Compilation will fail at line 5.
Compilation will fail at line 6.
Compilation will fail at line 14.
Compilation will fail at line 17.
第12题:
Line 13
Line 14
Line 18
Line 20
第13题:
1. public class Test { 2. public static String output =””; 3. 4. public static void foo(int i) { 5. try { 6. if(i==1) { 7. throw new Exception(); 8. } 9. output += “1”; 10. } 11. catch(Exception e) { 12. output += “2”; 13. return; 14. } 15. finally { 16. output += “3”;17. } 18. output += “4”; 19. } 20. 21. public static void main(String args[]) { 22. foo(0); 23. foo(1); 24. 25. }26. } What is the value of the variable output at line 23?()
第14题:
public class Score implements Comparable
第15题:
11. class Payload { 12. private int weight; 13. public Payload(int wt) { weight = wt; } 13. public void setWeight(mt w) { weight = w; } 15. public String toString { return Integer.toString(weight); } 16. } 17. 18. public class TestPayload { 19. static void changePayload(Payload p) { 20. /* insert code here */ 21. } 22. 23. public static void main(String[] args) { 24. Payload p = new Payload(); 25. p.setWeight(1024); 26. changePayload(p); 27. System.out.println(”The value of p is “+ p); 28. } 29. } Which statement, placed at line 20, causes the code to print “The value of p is 420.”?()
第16题:
11. class Person { 12. String name = “No name‟; 13. public Person(String nm) { name = nm; } 14. } 15. 16. class Employee extends Person { 17. String emplD = “0000”; 18. public Employee(String id) { empID = id; } 19. } 20. 21. public class EmployeeTest { 22. public static void main(String[] args) { 23. Employee e = new Employee(”4321”); 24. System.out.println(e.empID); 25. } 26. } What is the result?()
第17题:
10. class Inner { 11. private int x; 12. public void setX( int x) { this.x = x; } 13. public int getX() { return x; } 14. } 15. 16. class Outer { 17. private Inner y; 18. public void setY( Inner y) { this.y = y; } 19. public Inner getY() { return y; } 20. } 21. 22. public class Gamma { 23. public static void main( String[] args) { 24. Outer o = new Outer(); 25. Inner i = new Inner(); 26.int n=10; 27. i.setX(n); 28. o.setY(i); 29. // insert code here 30. System.out.println( o.getY().getX()); 31. } 32. } Which three code fragments, added individually at line 29, produce the output 100?()
第18题:
10. interface Foo { 11. int bar(); 12. } 13. 14. public class Beta { 15. 16. class A implements Foo { 17. public int bar() { return 1; } 18. } 19. 20. public int fubar( Foo foo) { return foo.bar(); } 21. 22. public void testFoo() { 23. 24. class A implements Foo { 25. public int bar() { return 2; } 26. } 27. 28. System.out.println( fubar( new A())); 29. } 30. 31. public static void main( String[] argv) { 32. new Beta().testFoo(); 33. } 34. } Which three statements are true?()
第19题:
Hello
Hello World
Compilation fails.
Hello World 5
The code runs with no output.
An exception is thrown at runtime.
第20题:
s.writeInt(x);
s.serialize(x);
s.writeObject(x);
s.defaultWriteObject();
第21题:
public int compareTo(Object o) {/*mode code here*/}
public int compareTo(Score other) {/*more code here*/}
public int compare(Score s1,Score s2){/*more code here*/}
public int compare(Object o1,Object o2){/*more code here*/}
第22题:
Foo { public int bar() { return 1; } }
new Foo { public int bar() { return 1; } }
newFoo() { public int bar(){return 1; } }
new class Foo { public int bar() { return 1; } }
第23题:
Compilation succeeds and 4 is printed.
Compilation …………… is printed.
An error on line 9 cause compilation to fail.
An error on line 14 cause compilation to fail.
Compilation succeeds but an exception is thrown at line 9.