Introduction to Java basics- Quiz1

You want subclasses in any package to have access to members of a superclass. Which is the most restrictive access that accomplishes this objective?


A. public B. private
C. protected D. transient
Answer & Explanation
Answer: Option C


Qstn-public class Outer 
{ 
    public void someOuterMethod() 
    {
        //Line 5 
    } 
    public class Inner { } 
    
    public static void main(String[] argv) 
    {
        Outer ot = new Outer(); 
        //Line 10
    } 
} 
Which of the following code fragments inserted, will allow to compile?


A. new Inner(); //At line 5
B. new Inner(); //At line 10
C. new ot.Inner(); //At line 10
D. new Outer.Inner(); //At line 10
Answer: Option A


Qstn- interface Base 
{
    boolean m1 ();
    byte m2(short s);
}
which two code fragments will compile?
interface Base2 implements Base {}
abstract class Class2 extends Base 
{ public boolean m1(){ return true; }}
abstract class Class2 implements Base {}
abstract class Class2 implements Base 
{ public boolean m1(){ return (7 > 4); }}
abstract class Class2 implements Base 
{ protected boolean m1(){ return (5 > 7) }}
A. 1 and 2 B. 2 and 3
C. 3 and 4 D. 1 and 5
Answer & Explanation
Answer: Option C






QSTN- Which three form part of correct array declarations?


public int a [ ]
static int [ ] a
public [ ] int a
private int a [3]
private int [3] a [ ]
public final int [ ] a
A. 1, 3, 4 B. 2, 4, 5
C. 1, 2, 6 D. 2, 5, 6
Answer & Explanation
Answer: Option C


Explanation:




qstn- public class Test { }
What is the prototype of the default constructor?
A. Test( ) B. Test(void)
C. public Test( ) D. public Test(void)
Answer & Explanation
Answer: Option C




QStN-What is the most restrictive access modifier that will allow members of one class to have access to members of another class in the same package?


A. public B. abstract
C. protected D. synchronized
E. default access
Answer & Explanation
Answer: Option E








QSTN- Which of the following is/are legal method declarations?


protected abstract void m1();
static final void m1(){}
synchronized public final void m1() {}
private native void m1();
A. 1 and 3
B. 2 and 4
C. 1 only
D. All of them are legal declarations.
Answer & Explanation
Answer: Option D






QSTN-Which cause a compiler error?


A. int[ ] scores = {3, 5, 7};
B. int [ ][ ] scores = {2,7,6}, {9,3,45};
C. String cats[ ] = {"Fluffy", "Spot", "Zeus"};
D. boolean results[ ] = new boolean [] {true, false, true};
E. Integer results[ ] = {new Integer(3), new Integer(5), new Integer(8)};
Answer & Explanation
Answer: Option B


QSTN-You want a class to have access to members of another class in the same package. Which is the most restrictive access that accomplishes this objective?


A. public B. private
C. protected D. default access
Answer & Explanation
Answer: Option D






QSTN- Which three are valid method signatures in an interface?


private int getArea();
public float getVol(float x);
public void main(String [] args);
public static void main(String [] args);
boolean setFlag(Boolean [] test);
A. 1 and 2 B. 2, 3 and 5
C. 3, 4, and 5 D. 2 and 4
Answer & Explanation
Answer: Option B






QSTN- What is the narrowest valid returnType for methodA in line 3?


public class ReturnIt 
{ 
    returnType methodA(byte x, double y) /* Line 3 */
    { 
        return (long)x / y * 2; 
    } 
}
A. int B. byte
C. long D. double
Answer & Explanation
Answer: Option D






QSTN- class A 
{  
    protected int method1(int a, int b) 
    {
        return 0; 
    } 
}
Which is valid in a class that extends class A?
A. public int method1(int a, int b) {return 0; }
B. private int method1(int a, int b) { return 0; }
C. public short method1(int a, int b) { return 0; }
D. static protected int method1(int a, int b) { return 0; }
Answer & Explanation
Answer: Option A






QSTN- Which one creates an instance of an array?


A. int[ ] ia = new int[15];
B. float fa = new float[20];
C. char[ ] ca = "Some String";
D. int ia[ ] [ ] = { 4, 5, 6 }, { 1,2,3 };
Answer & Explanation
Answer: Option A




QSTN- Which two of the following are legal declarations for nonnested classes and interfaces?


final abstract class Test {}
public static interface Test {}
final public class Test {}
protected abstract class Test {}
protected interface Test {}
abstract public class Test {}
A. 1 and 4 B. 2 and 5
C. 3 and 6 D. 4 and 6
Answer & Explanation
Answer: Option C






QSTN- Which of the following class level (nonlocal) variable declarations will not compile?


A. protected int a;
B. transient int b = 3;
C. private synchronized int e;
D. volatile int d;
Answer & Explanation
Answer: Option C






QSTN-
Which two cause a compiler error?


float[ ] f = new float(3);
float f2[ ] = new float[ ];
float[ ]f1 = new float[3];
float f3[ ] = new float[3];
float f5[ ] = {1.0f, 2.0f, 2.0f};
A. 2, 4 B. 3, 5
C. 4, 5 D. 1, 2
Answer & Explanation
Answer: Option D




QSTN- Given a method in a protected class, what access modifier do you use to restrict access to that method to only the other members of the same class?


A. final B. static
C. private D. protected
E. volatile
Answer & Explanation
Answer: Option C






QSTN-  Which is a valid declaration within an interface?


A. public static short stop = 23;
B. protected short stop = 23;
C. transient short stop = 23;
D. final void madness(short stop);
Answer & Explanation
Answer: Option A