Java Access Modifiers

🎭 Java Access Modifiers – Who Gets to Peek? 🤔

Java has four access modifiers that control who can snoop around in your classes, variables, methods, and constructors. Think of them as security levels at a top-secret agency! 🕵️‍♂️

1. The VIP List – Access Modifiers at a Glance 👀

Access Modifier	Who Can Peek? 👀
public	Open to the world! 🌍
protected	Accessible to package mates and subclass spies! 🕵️‍♀️
default (package-private)	Only package buddies allowed! 🚪
private	Only the class itself can access. Strictly confidential! 🔒

The access levels go from the friendliest (public) to the most exclusive (private):

Note: public > protected > default (package-private) > private

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1.1. public – The Social Butterfly 🦋

A public class, method, or constructor is available to everyone, everywhere. Think of it like a celebrity – anyone can approach!

public class Data {

  private String format;

  public String getFormat() {
    return this.format;
  }

  public void setFormat(String format) {
    this.format = format;
  }
}

Fun Fact

All fields in an interface are public static final by default! No secrets there! 🤐

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1.2. protected – Friends and Family Only 🤝

A protected member is visible in the same package and to subclasses outside the package. It's like an exclusive club – your package-mates and family (subclasses) are welcome!

public class Data {

  protected void displayMessage() {
    System.out.println("Test message");
  }
}

📌 In the Same Package

public class Main {
  public static void main(String[] args) {
    Data data = new Data();
    data.displayMessage(); // Works fine 🎉
  }
}

❌ Outside the Package? No Entry

If you try to access displayMessage() outside its package without inheritance, Java will slam the door shut! 🚪❌

'displayMessage()' has protected access in 'com.example.Data'

✅ Inheritance to the Rescue

public class Main extends Data {
  public static void main(String[] args) {
    Main main = new Main();
    main.displayMessage(); // Works! 🎊
  }
}

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1.3. default (package-private) – The Neighborhood Watch 👀

If you don’t specify an access modifier, Java assumes it's 'default' (a.k.a package-private). That means only classes in the same package can access it.

public class Data {
  void displayMessage() {
    System.out.println("Default Test message");
  }
}

❌ Not Allowed Outside the Package

'displayMessage()' is not public in 'com.example.Data'. Cannot be accessed from outside package.

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1.4. private – Top Secret! 🚫

A private member is the most restrictive – only accessible within the class. It's like having a personal diary 🔐 – no one else can read it!

public class Data {

  private void displayMessage() {
    System.out.println("Top Secret Message!");
  }
}

Attempting to access it from another class? 🚨 Access Denied! 🚨

'displayMessage()' has private access in 'Data'

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2. Levels of Access Control 🔑

There are two levels of access control in Java:

1. Class-level access – A class can be public or default (package-private). Top-level classes cannot be private or protected.
2. Member-level access – Fields, methods, and constructors can use public, protected, default, or private.

🔹 Local variables and parameters? They cannot have access modifiers – they are automatically private to the method! 🤫

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3. Conclusion – Choose Wisely! 🧐

Access levels matter in two big ways:

1. When using external classes – Access levels determine what parts of those classes you can use.
2. When writing your own classes – You decide what to expose and what to keep private. A well-thought-out access control strategy prevents unintended misuse and errors! 🚀

Quick Tips 📌

✅ Use private whenever possible – Only expose what’s necessary! 🔒 ✅ Use default for package-scoped access. 🏡 ✅ Use protected for inheritance scenarios. 👪 ✅ Use public when you want everyone to have access. 🌎

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🎉 Happy Learning! 🚀