MAD2019JAVAQuiz

Which of the following is FALSE about abstract classes in Java

• If we derive an abstract class and do not implement all the abstract methods, then the derived class should also be marked as abstract using 'abstract' keyword

• Abstract classes can have constructors

• A class can be made abstract without any abstract method

• A class can inherit from multiple abstract classes.

Which of the following is FALSE about arrays on Java

• A java array is always an object

• Length of array can be changed after creation of array

• Arrays in Java are always allocated on heap

Predict the output?

// file name: Main.java

public class Main {

public static void main(String args[]) {

int arr[] = {10, 20, 30, 40, 50};

for(int i=0; i < arr.length; i++)

{

System.out.print(" " + arr[i]);

}

}

}

• 10 20 30 40 50

• Compiler Error

• Run time Error

• 10 20 30 40

Predict the output of following Java program.

class Test {

public static void main(String[] args) {

for(int i = 0; 0; i++)

{

System.out.println("Hello");

break;

}

}

}

• Hello

• Empty Output

• Compiler error

• Run time error

Predict the output of following Java program

class T {

int t = 20;

T() {

t = 40;

}

}

class Main {

public static void main(String args[]) {

T t1 = new T();

System.out.println(t1.t);

}

}

• 20

• 40

• compiler error

• run time error

Output of following Java program?

class Main {

public static void main(String args[]) {

int x = 0;

int y = 10;

int z = y/x;

}

}

• compiler error

• compiles and runs fine

• Compiles fine but throws Arithmetic Exception exception

Which of the following is/are true about packages in Java?

1) Every class is part of some package.

2) All classes in a file are part of the same package.

3) If no package is specified, the classes in the file

go into a special unnamed package

4) If no package is specified, a new package is created with

folder name of class and the class is put in this package.

• Only 1, 2 and 3

• Only 1,2 and 4

• only 1

• non of the above

class Test {

int i;

}

class Main {

public static void main(String args[]) {

Test t;

System.out.println(t.i);

}

• 0

• garbage value

• compiler error

• run time error

Where are the following four methods commonly used?

1) public void add(Component c)

2) public void setSize(int width,int height)

3) public void setLayout(LayoutManager m)

4) public void setVisible(boolean)

• Graphics class

• Component class

• Both A and B

• none of the above

In order to transfer data between a database and an application written in the Java programming language, the JDBC API provides which of these methods?

• Methods on the ResultSet class for retrieving SQL SELECT results as Java types.

• Methods on the PreparedStatement class for sending Java types as SQL statement parameters.

• Methods on the CallableStatement class for retrieving SQL OUT parameters as Java types.

• All mentioned above