Can you explain the difference b/n abtract and interface
with a good example,?In what cases we have use abtract and
what case interface?
Answers were Sorted based on User's Feedback
Answer / srihari
Interfaces are used to create prototype of classes. Interfaces would be using high-level access specifiers(public).
Abstraction is a mechanism in Java to expose the essential features of the class. Different levels of abstraction is achieved through Access specifiers.
| Is This Answer Correct ? | 6 Yes | 0 No |
Answer / nt.jayan
Interface contains final variable and method signatures
only. All of this method and variable are should be public.
In Technically interface like Pure Abstract class.
Abstract class contains both abstract method also may having
some method defination. When we want to use some of the
functionality in abstract we use Abstract class.
Also, By using Interface we achieve multiple inheritence
using Implements. When we use Abstract class we can extends
only.
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / manasa
Abstract means 4 which we cant give a concrete definition
for ex wtz d def for animal v cant give so v say animal as
abstract.
Interface came into existence to facilitate multiple
inheritance
Eg for abstract: animal is a abstract class and it contains
both abstract n non-abstract methods
But remember a non abstract class cannot contain abstract
methods
Suppose consider area as method and it is different for
diff shapes like circle,rectangle,square.... here area vil
b calculated for all d shapes bt their implementation is
diff n instead of callin dat area method again n again v
vil declare it once
Now lets move on to interface
for eg if we give a compliment to girl dat she sings like
lata mangeshkar n here both dat girl n lata are connected
together by a sing method n these both r two unrelated
things and in this case we use interface.....
thank u guys have a nice tym.....
| Is This Answer Correct ? | 0 Yes | 1 No |
Answer / ipdarsini
Interface is the 1st Level.here methods does not contain
any executable code.just it contains only declerations.here
in interface level we does not know anything.
Abstract class is a class which contains methods which may
contains exceutable code or not.this is the 2 nd level.here
in abstarct class level we know some thing.
for ex take a maruthi car.......
in interface level.
we doesn't know about egine company........some parts.....
we know .....but its not sure...
in abstract class level
for ex take a maruthi 800 car......
we knows the comapany of that car.
here we know about some thing bcz here they mentioned
maruthi 800....
thats the difference.....
| Is This Answer Correct ? | 0 Yes | 5 No |
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3.2 Consider the following class: public class Point { protected int x, y; public Point(int xx, int yy) { x = xx; y = yy; } public Point() { this(0, 0); } public int getx() { return x; } public int gety() { return y; } public String toString() { return "("+x+", "+y+")"; } } Say you wanted to define a rectangle class that stored its top left corner and its height and width as fields. 3.2.1 Why would it be wrong to make Rectangle inherit from Point (where in fact it would inherit the x and y coordinates for its top left corner and you could just add the height and width as additional fields)? (1) 8 Now consider the following skeleton of the Rectangle class: public class Rectangle { private Point topLeft; private int height, width; public Rectangle(Point tl, int h, int w) { topLeft = tl; height = h; width = w; } public Rectangle() { this(new Point(), 0, 0); } // methods come here } 3.2.2 Explain the no-argument constructor of the Rectangle class given above. 3.2.3 Write methods for the Rectangle class to do the following: • a toString() method that returns a string of the format "top left = (x, y); height = h; width = w " where x, y, h and w are the appropriate integer values. • an above() method that tests whether one rectangle is completely above another (i.e. all y values of the one rectangle are greater than all y values of the other). For example, with the following declarations Rectangle r1 = new Rectangle(); Rectangle r2 = new Rectangle(new Point(2,2), 1, 4); the expression r2.above(r1) should give true, and r2.above (r2) should give false. (You can assume that the height of a rectangle is never negative.) (2) (5)
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