How is data hiding and access control to internal class data implemented in Java?

In Java, hiding internal class data is achieved through encapsulation — restricting access to class fields and methods.

For this, access modifiers are used:

• private — access only within the class.
• protected — access within the package and subclasses.
• public — access from everywhere.

Usually, class fields are declared as private, and public methods — getters and setters — are created for access:

public class User {
    private String name; // hidden field

    public String getName() { // getter
        return name;
    }

    public void setName(String name) { // setter
        this.name = name;
    }
}

This approach allows controlling how data is modified and used, ensuring the security and integrity of the object.