Compilation will succeed if a extends b.
Compilation will succeed if b extends a.
Compilation will always fail because of an error in line 7.
Compilation will always fail because of an error in line 8.
第1题:
1. class BaseClass { 2. private float x = 1.of; 3. protected float getVar() { return x; } 4. } 5. class SubClass extends BaseClass { 6. private float x = 2.Of; 7. // insert code here 8. } Which two are valid examples of method overriding when inserted at line 7?()
第2题:
1. public interface A { 2. public void doSomething(String thing); 3. } 1. public class AImpl implements A { 2. public void doSomething(String msg) { } 3. } 1. public class B { 2. public A doit() { 3. // more code here 4. } 5. 6. public String execute() { 7. // more code here 8. } 9. } 1. public class C extends B { 2. public AImpl doit() { 3. // more code here 4. } 5. 6. public Object execute() { 7. // more code here 8. } 9. } Which statement is true about the classes and interfaces in the exhibit?()
第3题:
1. class A { 2. public int getNumber(int a) { 3. return a + 1; 4. } 5. } 6. 7. class B extends A { 8. public int getNumber (int a) { 9. return a + 2 10. } 11. 12. public static void main (String args[]) { 13. A a = new B(); 14. System.out.printIn(a.getNumber(0)); 15. } 16. } What is the result?()
第4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5题:
1. class A { 2. public byte getNumber () { 3. return 1; 4. } 5. } 6. 7. class B extends A { 8. public short getNumber() { 9. return 2; 10. } 11. 12. public static void main (String args[]) { 13. B b = new B (); 14. System.out.printIn(b.getNumber()) 15. } 16. } What is the result?()
第6题:
1. class Super { 2. public float getNum() { return 3.0f; } 3. } 4. 5. public class Sub extends Super { 6. 7. } Which method, placed at line6, causes compilation to fail?()
第7题:
1. public class A { 2. public void doit() { 3. } 4. public String doit() { 5. return “a”; 6. } 7. public double doit(int x) { 8. return 1.0; 9. } 10.} What is the result?()
第8题:
class A { public String toString () { return “4”; } } class B extends A { 8. public String toString () { return super.toString() + “3”; } } public class Test { public static void main(Stringargs) { System.out.printIn(new B()); } } What is the result?()
第9题:
1. class SuperClass { 2. public a geta() { 3. return new a(); 4. } 5. } 6. class SubClass extends SuperClass { 7. public b geta() { 8. return new b(); 9. } 10. } Which is true?()
第10题:
1. class A { 2. public String toString () { 3. return “4”; 4. } 5. } 6. class B extends A { 7. public String toString () { 8. return super.toString() + “3”; 9. } 10. } 11. public class Test { 12. public static void main(String[]args) { 13. System.out.printIn(new B()); 14. } 15. } What is the result?()