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Modifiers-

💡Definition-

These are the keywords which  modifies properties of classes and fields.

💡Types of modifiers-

1- Access modifiers
2-Non-access modifiers

Quick overview –

💡1-Access modifier-

Modifies accessibility of   classes and fields.

-Controls visibility.

(i)Private    – only within class

(ii)Default   – only within package.

(iii)Protected  – within package and outside the package using inheritance

(iv)Public        – everywhere

Note- classes can’t be private and protected.
Note- Local variables can’t have any access modifier

code samples are here

1- Program to demonstrate access modifiers on variables

i- Program for class ExUsingVar

package AccessModifiers8;
public class ExUsingVar {
public int a=10;
private int b=20;
protected int c=30;
int d=40;

public static void main(String[] args) {
ExUsingVar e1 =new ExUsingVar();
System.out.println(e1.a);
System.out.println(e1.b);
System.out.println(e1.c);
System.out.println(e1.d);
}
}

ii-Program for class ExUsingVar1

package AccessModifiers8;
public class ExUsingVar1 {

public static void main(String[] args) {
ExUsingVar e1 =new ExUsingVar();
System.out.println(e1.a);
System.out.println(e1.b);
System.out.println(e1.c);
System.out.println(e1.d);
}
}

iii-Program to show ExUsingVar3

package AccessModifiers8_1;
import AccessModifiers8.ExUsingVar;

public class ExUsingVar3 {

public static void main(String[] args) {
ExUsingVar e1 =new ExUsingVar();
System.out.println(e1.a);
 System.out.println(e1.b);
 System.out.println(e1.c);
 System.out.println(e1.d);
}

}

💡2-Non Access Modifiers-  (Final,Static,abstract,Transient,Synchronized,Volatile, native, strict)

💡1-Final-

used to restrict the user.

💡(a)final variable  –

can’t change the value

💡(b) final method –

can’t override

💡(c) final class–

can’t inherit

💡2-Static-

-static belongs to class rather than objects.
💡(a) static variable
-gets memory only once at the time of class loading.
-used to refer the common property of all objects

💡(b) static method
– can be invoked without an instance/object
-can access static variable

💡(c) static nested Class
-can access static data members of outer class

-object is created in scope of outer class

💡(d) static block
– executes even before main method
-used to initialize static data members

💡(E) STATIC method in interface-
– Static methods in interface can have body
– Can be invoked on Interface name only
– Can’t be override by inheritance

💡3- Abstract –

-Used in abstraction(oops concept)
-can be applied on-
a- Abstract class
b- Abstract method

💡4-Transient-

– prevents serialization of value.(Io package concept)
-only for variable

💡5-Synchronized-(multi-threading concept)

-prevents sharing by more than one threads at a time
– can be
a- synchronized method
b- synchronized block

💡6-Volatile-(multi-threading concept)

– Allows modification at run-time.
– only for variable

💡7- Native- JNI (Java Native Interface)

– Only for native/foreign methods
– Methods which are implemented in c/c++ are called as native/foreign methods

💡8- Strict – (strictfp as keyword)

– Ensures that result is same for every platform while performing floating point calculations

Interview Questions —

• What is difference between access and non-access modifiers?
• What is default access modifiers, how to use it on class?
• What is difference static and final modifiers?