Access modifiers in Java

In Java, access specifiers (also called access modifiers) define the visibility and accessibility of classes, methods, variables, and constructors. They control which parts of a program can access certain members of a class. Java has four main access specifiers:

1. public

• Visibility: Everywhere, i.e., from any other class or package.
• Usage: When you want a class, method, or variable to be accessible universally.
• Example:

public class MyClass {
    public int number;
    
    public void display() {
        System.out.println("Hello");
    }
}

public class MyClass {
    public int number;
    
    public void display() {
        System.out.println("Hello");
    }
}

2. private

• Visibility: Only within the same class.
• Usage: When you want to encapsulate data, restricting direct access from outside the class.
• Example:

class MyClass {
    private int number;
    
    private void display() {
        System.out.println("Hello");
    }
    
    // Public method to access private members
    public int getNumber() {
        return number;
    }
}

class MyClass {
    private int number;
    
    private void display() {
        System.out.println("Hello");
    }
    
    // Public method to access private members
    public int getNumber() {
        return number;
    }
}

3. protected

• Visibility: Same package + subclasses (even if they are in a different package).
• Usage: For inheritance, when you want derived classes to access members, but not everyone.
• Example:

class Parent {
    protected int number;
}

class Child extends Parent {
    void show() {
        System.out.println(number); // Accessible because it's protected
    }
}

class Parent {
    protected int number;
}

class Child extends Parent {
    void show() {
        System.out.println(number); // Accessible because it's protected
    }
}

4. Default (no modifier)

• Visibility: Only within the same package.
• Usage: When you omit any access specifier, it’s called package-private or default access.
• Example:

class MyClass {
    int number; // default access
}

class MyClass {
    int number; // default access
}

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