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1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2题:
1. public class SwitchTest { 2. public static void main (String []args) { 3. System.out.PrintIn(“value =” +switchIt(4)); 4. } 5. public static int switchIt(int x) { 6. int j = 1; 7. switch (x) { 8. case 1: j++; 9. case 2: j++; 10. case 3: j++; 11. case 4: j++; 12. case 5: j++; 13. default:j++; 14. } 15. return j + x; 16. } 17. } What is the output from line 3?()
第3题:
10. interface Foo { int bar(); } 11. public class Sprite { 12. public int fubar( Foo foo) { return foo.bar(); } 13. public void testFoo() { 14. fubar( 15. // insert code here 16.); 17. } 18. } Which code, inserted at line 15, allows the class Sprite to compile?()
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:
现有: 1. class Synapse { 2. protected int gap() { return 7; } 3. } 4. 5. class Creb extends Synapse { 6. // insert code here 7. } 分别插入到第 6 行,哪三行可以编译?()
第6题:
class A { public byte getNumber() { return 1; } } class B extends A { public short getNumber() { return 2; } public static void main(String args[]) { B b = new B(); System.out.println(b.getNumber()); } } What is the result?()
第7题:
1. class A { 2. public byte file Number ( ) { 3. return l; 4. } 5. } 6. 7. Class B extends A { 8. public short getNumber( ) { 9. return 2; 10. } 11. 12. public short getNumber( ) { 13. B b = new B( ); 14. System.out.printIn(b.getNumber( )); 15. } 16. } What is the result()?
第8题:
1. public class A { 2. 3. private int counter = 0; 4. 5. public static int getInstanceCount() { 6. return counter; 7. } 8. 9. public A() { 10. counter++; 11. } 12. 13. } Given this code from Class B: 25.A a1 =new A(); 26. A a2 =new A(); 27. A a3 =new A(); 28. System.out.printIn(A.getInstanceCount() ); What is the result?()
第9题:
1. public class A { 2. public String doit(int x, int y) { 3. return “a”; 4. } 5. 6. public String doit(int... vals) { 7. return “b”; 8. } 9. } Given: 25. A a=new A(); 26. System.out.println(a.doit(4, 5)); What is the result?()
第10题:
The program runs and prints “0”
The program runs and prints “1”
The program runs but aborts with an exception.
An error “possible undefined variable” at line 4 causes compilation to fail.
An error “possible undefined variable” at line 9 causes compilation to fail.
第11题:
0
3
4
5
The code will not compile.
第12题:
An exception is thrown at runtime.
Compilation fails because of an error in line 7.
Compilation fails because of an error in line 4.
Compilation succeeds and no runtime errors with class A occur.
第13题:
1. public class X { 2. public static void main (String[]args) { 3. int [] a = new int [1] 4. modify(a); 5. System.out.printIn(a[0]); 6. } 7. 8. public static void modify (int[] a) { 9. a[0] ++; 10. } 11. } What is the result?()
第14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15题:
1. class Pizza { 2. java.util.ArrayList toppings; 3. public final void addTopping(String topping) { 4. toppings.add(topping); 5. } 6. } 7. public class PepperoniPizza extends Pizza { 8. public void addTopping(String topping) { 9. System.out.println(”Cannot add Toppings”); 10. } 11. public static void main(String[] args) { 12. Pizza pizza = new PepperoniPizza(); 13. pizza.addTopping(”Mushrooms”); 14. } 15. } What is the result?()
第16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17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?()
第18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19题:
1. public class test ( 2. public static void main(string args[]) { 3. int 1= 0; 4. while (i) { 5. if (i==4) { 6. break; 7. } 8. ++i; 9. } 10. 11. } 12. ) What is the value of i at line 10?()
第20题:
class A { public int getNumber(int a) { return a + 1; } } class B extends A { public int getNumber (int a) { return a + 2 } public static void main (String args) { A a = new B(); System.out.printIn(a.getNumber(0)); } } What is the result? ()
第21题:
1
2
An exception is thrown at runtime.
Compilation fails because of an error in line 8.
Compilation fails because of an error in line 14.
第22题:
Line 26 prints “a” to System.out.
Line 26 prints „b” to System.out.
An exception is thrown at line 26 at runtime.
Compilation of class A will fail due to an error in line 6.
第23题:
Change line 2 to: public int a;
Change line 2 to: protected int a;
Change line 13 to: public Sub() { this(5); }
Change line 13 to: public Sub() { super(5); }
Change line 13 to: public Sub() { super(a); }