SCJP1.4 考试资料.zip_zip

Q1.

Given:

1. package foo;

2.

3. import java.util.Vector;

4.

5. private class MyVector extends Vector {

6. int i = 1;

7. public MyVector() {

14. i = 4;

15. }

16. public static void main(String args[]) {

17. MyVector v = new MyNewVector();

18. }

19. }

What is the result?

A. Compilation succeeds.

B. Compilation fails because of an error at line 4.

C. Compilation fails because of an error at line 5.

13. A e = new A();

14. B b = new B();

15. a.s(b);

16. b = null;

17. a = null;

18. System.out.printIn(“start completed”);

19. }

When is the B object, created in line 14, eligible for garbage collection?

A. After line 16.

B. After line 17.

1. class TestA {

2. TestB b;

3. TestA() {

4. b = new TestB(this);

5. }

6. }

7. class TestB {

8. TestA a;

9. TestB(TestA a) {

16. // ...code continues on

17. }

18. void makeThings() {

19. TestA test = new TestA();

20. }

21. }

Which two statements are true after line 15, before main completes? (Choose two)

A. Line 15 causes a stack overflow.

B. An exception is thrown at runtime.

C. The object referenced by a is eligible for garbage collection.

Answer: C, F.

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;

B. Line 14

Answer: B.

Q5.

Which statement is true about assertion in the Java programming language?

A. Assertion expressions should not contain side effects.

B. Assertion expression values can be any primitive type.

C. Assertion should be used for enforcing preconditions on public methods.

D. An AssertionError thrown as a result of a failed assertion should always be handled by

the enclosing method.

B. if (x > 0) {

} else {

assert (x==0);

}

C. public void aMethod(int x) {

assert (x > 0);

}

D. assert (invariantCondition());

return retval;

E. switch (x) {

Answer: C.

1. public class X {

2. public static void main(String [] args) {

3. try {

4. badMethod();

5. System.out.print(“A”);

6. }

7. catch (RuntimeException ex) {

8. System.out.print(“B”);

9. }

10. catch (Exception ex1) {

15. }

18. public static void badMethod() {

19. throw new RuntimeException();

20. }

21. }

What is the result?

A. BD

B. BCD

C. BDE

D. BCDE

1. public class X {

2. public static void main(String [] args) {

3. try {

4. badMethod();

5. System.out.print(“A”);

6. }

7. catch (Exception ex) {

8. System.out.print(“B”);

9. }

10. finally {

14. }

18. }

What is the result?

A. AB

B. BC

C. ABC

D. BCD

E. Compilation fails.

Answer: D.

Q9.

D. Any statement that can throw an Exception must be enclosed in a try block.

Q10.

Given:

11. for( int i min; i <max; i++) {

12. System.out.printIn(i);

13. }

If min and max are arbitrary integers, what gives the same result?

A. init i = min;

while( i < max ) {

D. for (int i=; i++<max; System.out.printIn(i));

Answer: D.

Q11.

Given:

11. for (int i =0; i < 4; i +=2) {

12. System.out.print(i + “”);

13. }

14. System.out.printIn(i);

What is the result?

D. Compilation fails.

Q12.

Given:

11. int i = 1,j = 10;

12. do{

13. if (i>j) {

14. continue;

15. }

16. j--;

17. } while (++i <6);

18. System.out.printIn(“i = “ +i+” and j = “+j);

D. i = 5 and j = 6