JAVA OOPS & Stream

🚀

JAVA OOPS & Stream

JAVA ACCESS MODIFIER

Modifier	Same Class	Same Package	Subclass (diff pkg)	Everywhere
public	✅ Yes	✅ Yes	✅ Yes	✅ Yes
protected	✅ Yes	✅ Yes	✅ Yes	❌ No
default (no modifier)	✅ Yes	✅ Yes	❌ No	❌ No
private	✅ Yes	❌ No	❌ No	❌ No

🔎 Explanation with Examples

1. public

Visible everywhere.

Best when you want your API accessible globally.


public class A {
    public int x = 10;
    public void show() {
        System.out.println("Public method");
    }
}

✅ Accessible in same class, package, subclass, and different package.


new A().show();

2. private

Visible only inside the same class.

No one else (not even subclasses) can touch it.


public class A {
    private int secret = 42;

    private void hidden() {
        System.out.println("Private method");
    }
}

❌ Can’t be accessed outside A. Even if B extends A, it cannot access secret.

3. protected

Visible in:

Same class ✅
Same package ✅
Subclasses in other packages ✅

But not visible in non-subclass classes of other packages.


package pkg1;

public class A {
    protected int y = 20;
    protected void greet() {
        System.out.println("Protected method");
    }
}

From pkg1.B (same package): ✅ Allowed

From pkg2.C extends A: ✅ Allowed

From pkg2.D (non-subclass): ❌ Not Allowed

4. default (package-private)

When you don’t write anything (no public, no private, no protected).

Visible only in the same package.


class A {   // 👈 no modifier → package-private
    void hello() {
        System.out.println("Default access");
    }
}

From pkg1.B: ✅ Allowed

From pkg2.C: ❌ Not Allowed

⚡ Quick Real-world Mapping

public → Open door, anyone can come in.

private → Locked in your room, only you can access.

protected → Family (subclasses + same package) can access.

default → Friends in the same neighborhood (package) can access.

Java Stram APIs

Built with Potion.so