Difference between Static and dynamic polymorphism

Static Polymorphism	Dynamic Polymorphism
1. It is otherwise called as compiler-time polymorphism.	1.It is otherwise called as run-time polymorphism.
2. Overloading is used to achieve this.	2.Both overriding and dynamic dispatch is used to achieve this.
3. It is also called as static binding as compiler is binding the method with the object based on the argument.	3. It is called as dynamic binding as JVM will decide from which class the method will be executed based on the object assign.
4.Static method can be overloaded.	4. Static method never follow dynamic dispatch concept.
5. All works are done at the compilation time by the compiler that's why called as static binding.	5. All works are done at the run-time by the JVM that's why called as dynamic binding.
6. It is achieved by the compiler at the compile time.	5. It is achieved by the JVM at the run-time.

Difference between Abstract class and interface in Java

Abstract class	Interface
1.  A class become abstract when we use ' abstract ' keyword before the class name.	1. No need of using any abstract keyword but we need to use ' interface ' keyword.
2. We can use instance variable.	2. We cannot use any instance variable.
3. Can define static/ non-static variable.	3. Variables are by-default static.
4. Can use static/ non-static method	4. Static and non-static both cannot be used.
5. Can use private and protected with the variable	5.  Cannot use private and protected with the variable.
6. Static and instance both initialization block are allowed.	6. Both static and instance initialization block are not allowed.
7. Constructor are used to initialize instance variable defined in abstract class.	7. Cannot define constructor in an interface.
8.Cannot be used for achieving multiple inheritance.	8. It is used to achieve multiple inheritance in java.
9. Can define final and non-final method but final method should not be abstract.	9. Cannot define final and non-final method.
10. Can define abstract and non-abstract method in an abstract class.	10.Cannot define non-abstract method and by-default method are abstract.
11.' extends ' keywords are used to extend abstract class.	11.' implements ' keyword are used to implement any interface.
12. It extends java.lang.Object class.	12.It cannot extend java.lang.Object class.
13. Can define main method in an abstract class.	13.Cannot define main method in an interface.
14. Instance ' inner class ' is allowed inside as abstract class.	14. Instance inner class in not allowed and will be converted into static inner class by compiler.

Difference between Primitive type and Reference type in Java

Primitive type	Reference type
1. It is predefined in any programming language.	1.It is predefined as well as user-defined in Object oriented language.
2. It is used to store value may be integer, decimal , floating or boolean.	2.It is used to store the reference value of the object and is of integer type.
3.Size of the primitive type are varies according to the type.	3. Reference type has fixed size of 8 Byte.
4.It doesn't point to any object as it simply stores the required value.	4. It always points to the corresponding object whose address is stored as a reference value.
5. int, float,char,short,byte etc are the example of primitive type	5. String, Array,Class, interface are the examples of reference type.

What are the differences between public and private access modifier in java

Public access modifier	Private access modifier
It is uses the public keyword in java .	It uses the private keyword in java.
Member defined using public is visible ANYWHERE.	Member defined using private is only visible to that class only.
Public can be used with class.	Private cannot be used with the class.
We can make an interface as public.	We cannot make an interface as private.

Difference Between Top-level class and Inner class in Java

Top-level class	Inner class
It cannot be declared as static.	It can be declared as static.
We cannot use private and protected access modifiers with top-level class	We can use private and protected access modifiers with inner class as it is the member of the outer class.
It can be executed independently by the JVM with its class name.	It cannot be executed independently but can be executed with the the help of its outer class
Syntax for .class file ->  < class_name > . class	Syntax for .class file ->  < outer_class > $ < inner_class > . class
It cannot have any local top- level class.	We can have local inner class.

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Difference between java and php

JAVA	PHP
1. Java is an object oriented language	1. PHP is a scripting language.
2. It provides better security than PHP	2. PHP has weaker security as compared to Java.
3.Frameworks are available for its every web architectural layer.	3. No such facility available in PHP
4. Maintenance is easier .	4. Maintenance is little difficult.
5. Project developed in java are costlier.	5. Project developed in PHP is little cheaper then Java.