JAVA Basic Study

11. int x = 3;

12. int y = 1;

13. if (x = y) {

14. System.out.println("x = " + x);

15. }

What is the result?

A. x = 1

B. x = 3

C. Compilation fails.

D. The code runs with no output.

E. An exception is thrown at runtime.

컴파일 에러 if 는 true or false 만 가능

1. public class Test {

2. public static void aMethod() throws Exception {

3. try {

4. throw new Exception();

5. } finally {

6. System.out.println("finally");

7. }

8. }

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

10. try {

11. aMethod();

12. } catch (Exception e) {

13. System.out.println("exception");

14. }

15. System.out.println("finished");

16. }

17. }

What is the result?

A. finally

B. exception

finished

C. finally

exception

finished

D. Compilation fails.

 

씨 throw new Exception(); 이 관건.

Given:

1. public interface Foo {

2. int k = 4;

3. }

Which three are equivalent to line 2? (Choose three)

A. final int k = 4;

B. public int k = 4;

C. static int k = 4;

D. abstract int k = 4;

E. volatile int k = 4;

F. protected int k = 4;

 

public static final 생략

1. package test1;

2. public class Test1 {

3. static int x = 42;

4. }

1. package test2;

2. public class Test2 extends test1.Test1 {

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

4. System.out.println("x = " + x);

5. }

6. }

What is the result?

A. x = 0

B. x = 42

C. Compilation fails because of an error in line 2 of class Test2.

D. Compilation fails because of an error in line 3 of class Test1.

E. Compilation fails because of an error in line 4 of class Test2.

 

이 : 디폴트라 다른 패키지에서 접근 불가. public 이면 가능.

1. class A {

2. protected int method1(int a, int b) { return 0; }

3. }

Which two are valid in a class that extends class A? (Choose two)

A. public int method1(int a, int b) { return 0; }

B. private int method1(int a, int b) { return 0; }

C. private int method1(int a, long b) { return 0; }

D. public short method1(int a, int b) { return 0: }

E. static protected int method1(int a, int b) { return 0; }

 

에이씨 : 오버라이딩

1. public class Delta {

2. static boolean foo(char c) {

3. System.out.print(c);

4. return true;

5. }

6. public static void main( String[] argv ) {

7. int i =0;

8. for ( foo('A'); foo('B')&&(i<2); foo('C')){

9. i++ ;

10. foo('D');

12. }

13. }

14. }

What is the result?

A. ABDCBDCB

B. ABCDABCD

C. Compilation fails.

D. An exception is thrown at runtime.

에이. 이런 문제 참 좋은 문제.