Java Review Questions

1. Explain about the following:

1. Encapsulation:

* Is the mechanism that binds together code and the data it manipulates, and keeps both safe from outside interference and misuse.

* It is a protective wrapper that prevents the code and the data from being arbitrarily accessed by other code defined outside the wrapper.

2. Inheritance.

* Is the process by which one object acquires the properties of another object.

* The inheritance makes it possible for one object to be a specific instance of a more general case.

3. Polymorphism.

* Is a feature that allows one interface to be used for a general class of actions.

* Described by the phrase “One interface, multiple methods”

* This means it is possible to design a generic interface to a group of related activities.

2. Discuss in details about the primitive data types of Java with examples.

Java defines 8 primitive types of Data:

4. Byte: The smallest integer type is byte. This is a signed 8-bit type

The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters.

5. Short: is a signed 16-bit type. It is probably the least used java type.

6. Int: the most commonly used integer type is int. it is a signed 32-bit type.

7. Long: is a signed 64-bit type and is useful for those occasions where an int type is not large enough to hold the desired value.

8. Float: the type float specifies a single-precision value that uses 32 bits of storage.

9. Double: double precision, as denoted by the double keyword, uses 64 bits to store value.

10. Char: In Java, the data type used to store characters is char.

11. Boolean: Java has a primitive type, called Boolean, for logical values. It can have only two possible values, true or false.

3. What is the output of the following program.

Public class Scope

{

public static void main(String args[])

{

int x=10;

if(x==10)

{

int y=20;...