Modifiers

Modifiers are keywords in Java that are used to change the meaning of a variable or method. In Java, modifiers are categorized into two types:
1. Access Modifiers
2. Non Access Modifiers

Access Modifiers

Access modifiers can be used to define access control for classes, methods and variables.

Types of Access Modifiers

• public
• private
• default
• protected

public: access modifiers is accessible everywhere. Example –
for class: public class Sample { }
for methods: public int add(a+b);
for variables: public int a;

private: access modifiers is accessible only within the class. Example –
private int a = 100;

default: if we don’t specify any modifier then it is treated as default. Example –
class Sample { }

protected: The protected access modifier is accessible only within package and outside of package through Inheritance. Example –
protected class Sample { }

Modifier	Within Class	Within Package	Outside of the package (through Inheritance)	Outside of the package
private	Yes	No	No	No
default	Yes	Yes	No	No
protected	Yes	Yes	Yes	No
public	Yes	Yes	Yes	Yes

Non Access Modifiers

Non-access modifiers do not change the accessibility of variables and methods, but they do provide them special properties.

Types of Non Access Modifiers

• static
• final
• abstract
• synchronized
• Volatile

static: modifier is used to create class variable and class methods which can be accessed without instance of a class.

final: modifier for finalizing class, methods and variable i.e. it prevents its content from being modified. Final field must be initialized when it is declared. Example –
final int a = 100;

abstract: modifier is used to create abstract classes and abstract methods.

synchronized and volatile modifiers, which are used for threads.

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