What are access modifiers in java explain with examples

In Java, access modifiers are keywords used to set the accessibility or visibility of classes, methods, variables, or constructors. They control the level of access that other classes have to these components.

There are four types of access modifiers in Java:

1. public: Members declared as public are accessible from any class. They have the widest scope among all access modifiers.

Example:

/*
 * Author: Zameer Ali
 * */
public class MyClass {
    public int publicVar;
    public void publicMethod() {
        // Code here
    }
}

2. protected: Members declared as protected are accessible within the same package and subclasses, even if they are in different packages.

Example:

/*
 * Author: Zameer Ali
 * */
public class MyClass {
    protected int protectedVar;
    protected void protectedMethod() {
        // Code here
    }
}

3. default (no modifier): Members with no explicit modifier (also known as package-private) are accessible within the same package but not from outside the package.

Example:

/*
 * Author: Zameer Ali
 * */
class MyClass {
    int defaultVar;
    void defaultMethod() {
        // Code here
    }
}

4. private: Members declared as private are accessible only within the same class. They have the narrowest scope among all access modifiers.

Example:

/*
 * Author: Zameer Ali
 * */
public class MyClass {
    private int privateVar;
    private void privateMethod() {
        // Code here
    }
}

Usage Examples:

/*
 * Author: Zameer Ali
 * */
public class Main {
    public static void main(String[] args) {
        MyClass obj = new MyClass();
        obj.publicVar = 10; // Accessing public variable
        obj.publicMethod(); // Accessing public method

        obj.protectedVar = 20; // Accessing protected variable
        obj.protectedMethod(); // Accessing protected method

        obj.defaultVar = 30; // Accessing default variable (within the same package)
        obj.defaultMethod(); // Accessing default method (within the same package)

        obj.privateVar = 40; // Error: privateVar has private access in MyClass
        obj.privateMethod(); // Error: privateMethod() has private access in MyClass
    }
}

In this example, publicVar and publicMethod() can be accessed from anywhere because they are declared as public. protectedVar and protectedMethod() are accessible because they are in the same package. defaultVar and defaultMethod() are accessible because they are in the same package and have default access. privateVar and privateMethod() are not accessible outside the MyClass because they are private.