Difference in Specifiers and Modifiers

In Java, the terms “access specifiers” and “access modifiers” are often used interchangeably, but they can have subtle differences in context. However, in most cases, they both refer to the keywords that control the access level of classes, methods, and variables. Let’s clarify these terms and highlight any nuances.

Access Specifiers

Access specifiers are generally considered to be a subset of access modifiers. They specifically refer to the keywords that define the accessibility or visibility of classes, methods, and variables. The primary access specifiers in Java are:

• 1. public
• 2. protected
• 3. default (no keyword)
• 4. private

Access Modifiers

Access modifiers is a broader term that not only includes access specifiers but also other keywords that modify the behavior of classes, methods, and variables. This can include keywords that do not directly relate to access control but affect how a method or variable can be used.

In addition to the access specifiers mentioned above, access modifiers can include:

• 1. static
• 2. final
• 3. abstract
• 4. synchronized
• 5. native
• 6. transient
• 7. volatile

Detailed Differences

Access Specifiers

• 1. public: Accessible from any other class.
• 2. protected: Accessible within the same package and by subclasses in other packages.
• 3. default: (no keyword) Accessible only within the same package.
• 4. private: Accessible only within the same class.

```java
public class Example {
    public int publicVar;
    protected int protectedVar;
    int defaultVar; // package-private
    private int privateVar;
}
```

Access Modifiers

• static: Indicates that a member belongs to the class itself rather than to any specific instance.
• final: Indicates that a variable’s value cannot be changed, a method cannot be overridden, or a class cannot be subclassed.
• abstract: Indicates that a method has no implementation or a class cannot be instantiated.
• synchronized: Used to control access to a method or block by multiple threads.
• native: Indicates that a method is implemented in platform-dependent code using JNI (Java Native Interface).
• transient: Prevents serialization of a field.
• volatile: Indicates that a variable’s value will be modified by different threads.

```java
public class Example {
    public static final int CONSTANT = 10;
    private transient int transientVar;
    private volatile boolean flag;

    public synchronized void synchronizedMethod() {
        // method body
    }

    public native void nativeMethod();

}

```

Summary

• Access Specifiers: Specifically refer to the keywords (`public`, `protected`, `default`, `private`) that define the visibility of classes, methods, and variables.
• Access Modifiers: A broader term that includes access specifiers as well as other keywords (`static`, `final`, `abstract`, `synchronized`, `native`, `transient`, `volatile`) that modify the behavior and properties of classes, methods, and variables.

In practice, “access modifiers” is the term most commonly used to refer to both access control and behavior modification keywords in Java.

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