Test
OCAJP7 part 3 - from book
Preguntas del test (20)
1Only public and protected constructors are inherited from super class if the subclass is not in the same package.
- AVerdadero
- BFalso
2Which constructor is valid in class BlaBla
- ABlaBla(BlaBla a)
- Bprivate BlaBla()
- Cpublic final BlaBla(int i)
- Dpublic static BlaBla(char o)
3Given the following code, which of these constructors can be added to class B without
causing a compile time error?
class A{
int i;
public A(int x) { this.i = x; }
}
class B extends A{
int j;
public B(int x, int y) {
super(x);
this.j = y;
}
}- AB( ) { }
- BB(int y ) { j = y; }
- CB(int y ) { super(y*2 ); j = y; }
- DB(int y ) { i = y; j = y*2; }
- EB(int z ) { this(z, z); }
4Consider the following array definitions:
int[] array1, array2[];
int[][] array3;
int[] array4[], array5[];
Which of the following are valid statements?- Aarray2 = array3;
- Barray2 = array4;
- Carray1 = array2;
- Darray4 = array1;
- Earray5 = array3
5What will be the result of trying to compile and execute of the following program?
public class TestClass{
public static void main(String args[] ){
int i = 0 ;
int[] iA = {10, 20} ;
iA[i] = i = 30 ;
System.out.println(""+ iA[ 0 ] + " " + iA[ 1 ] + " "+i) ;
}
}- AIt will throw ArrayIndexOutofBoundsException at Runtime.
- BCompile time Error.
- CIt will prints 10 20 30
- DIt will prints 30 20 30
- EIt will prints 0 20 30
6What will the following program print?
class Test{
public static void main(String[] args){
int i = 4;
int ia[][][] = new int[i][i = 3][i];
System.out.println( ia.length + ", " + ia[0].length+", "+ ia[0][0].length);
}
}- AIt will not compile.
- B3, 4, 3
- C3, 3, 3
- D4, 3, 4
- E4, 3, 3
7Consider the following program...
class ArrayTest{
public static void main(String[] args){
int ia[][] = { {1, 2}, null };
for (int i = 0; i < 2; i++)
for (int j = 0; j < 2; j++)
System.out.println(ia[i][j]);
}
}
Which of the following statements are true?- AIt will not compile.
- BIt will throw an ArrayIndexOutOfBoundsException at Runtime.
- CIt will throw a NullPointerException at Runtime.
- DIt will compile and run without throwing any exceptions.
- ENone of the above.
8Consider the following class...
class Test{
public static void main(String[ ] args){
int[] a = { 1, 2, 3, 4 };
int[] b = { 2, 3, 1, 0 };
System.out.println( a [ (a = b)[3] ] );
}
}
What will it print when compiled and run ?- AIt will not compile.
- BIt will throw ArrayIndexOutOfBoundsException when run.
- CIt will print 1.
- DIt will print 3.
- EIt will print 4
- FIt will print 0
9Given the following program, which statements are true?
// Filename: TestClass.java
public class TestClass{
public static void main(String args[]){
A[] a, a1;
B[] b;
a = new A[10]; a1 = a;
b = new B[20];
a = b; // 1
b = (B[]) a; // 2
b = (B[]) a1; // 3
}
}
class A { }
class B extends A { }- ACompile time error at line 3.
- BThe program will throw a java.lang.ClassCastException at the line labelled 2 when run.
- CThe program will throw a java.lang.ClassCastException at the line labelled 3 when run.
- DThe program will compile and run if the (B[ ] ) cast in the line 2 and the whole line 3 is removed.
10Which of these statements are true?
- AIf a RuntimeException is not caught, the method will terminate and normal
execution of the thread will resume. - BAn overriding method must declare that it throws the same exception classes as the
method it overrides. - CThe main method of a program can declare that it throws checked exceptions.
- DA method declaring that it throws a certain exception class may throw instances of
any subclass of that exception class. - Efinally blocks are executed if and only if an exception gets thrown while inside the
corresponding try block.
- AIf a RuntimeException is not caught, the method will terminate and normal
11Consider the following code...
public class TestClass{
class MyException extends Exception {}
public void myMethod() throws XXXX{
throw new MyException();
}
}
Can we replace XXXX with MyException?- AVerdadero
- BFalso
12What will the following program print?
class Test{
public static void main(String[] args){
int i = 4;
int ia[][][] = new int[i][i = 3][i];
System.out.println( ia.length + ", " + ia[0].length+", "+ ia[0][0].length);
}
}- AIt will not compile.
- B3, 4, 3
- C3, 3, 3
- D4, 3, 4
- E4, 3, 3
13What will the following code print ?
class Test{
public static void main(String[] args){
int k = 1;
int[] a = { 1 };
k += (k = 4) * (k + 2);
a[0] += (a[0] = 4) * (a[0] + 2);
System.out.println( k + " , " + a[0]);
}
}- AIt will not compile.
- B4 , 4
- C25 , 25
- D13 , 13
- ENone of the above.
14What will the following code print when compiled and run?
class Base{
void methodA(){
System.out.println("base - MethodA");
}
}
class Sub extends Base{
public void methodA(){
System.out.println("sub - MethodA");
}
public void methodB(){
System.out.println("sub - MethodB");
}
public static void main(String args[]){
Base b=new Sub(); //1
b.methodA(); //2
b.methodB(); //3
}
}- Asub - MethodA and sub - MethodB
- Bbase - MethodA and sub - MethodB
- CCompile time error at //1
- DCompile time error at //2
- ECompile time error at //3
15What will be printed?
class A1 {
static int i;
}
class A {
public static void main(String[] args) {
A1 a1 = null;
System.out.println(a1.i);
}
}- A10
- BThis code will not compile.
- CNullpointerException will be thrown
- D0
16What will be the output of:
Short k = 9; Integer i = 9; System.out.println(k == i);
Please provide argumentation to your answer.- Atrue
- Bfalse
- CCompilation error
- DException in runtime
- EOther
17Consider the following code:
class A{
public XXX m1(int a){
return a*10/4-30;
}
}
class A2 extends A{
public YYY m1(int a){
return a*10/4.0;
}
}
What can be substituted for XXX and YYY so that it can compile without any
problems?- Aint, int
- Bint, double
- Cdouble, double
- Ddouble, int
- ENothing, they are simply not compatible.
18Consider the following code:
class A{
A() { print();
}
void print() { System.out.println("A"); }
}
class B extends A{
int i =
Math.round(3.5f);
public static void main(String[] args){
A a = new B();
a.print();
}
void print() { System.out.println(i); }
}
What will be the output when class B is run ?- AIt will print A, 4.
- BIt will print A, A
- CIt will print 0, 4
- DIt will print 4, 4
- ENone of the above.
19Consider :
class A { public void perform_work(){} }
class B extends A { public void perform_work(){}
class C extends B { public void perform_work(){}
}
}
How can you let perform_work() method of A to be called from an instance method in C?- A( (A) this ).perform_work( );
- Bsuper.perform_work( );
- Csuper.super.perform_work( );
- Dthis.super.perform_work( );
- EIt is not possible.
20Expression (s instanceof java.util.Date) will return false if 's' was declared
as a variable of class java.lang.String .- AVerdadero
- BFalso
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