Can you tell about the different types of data access mechanisms and class member access in Java?

In Java, there are four main levels of access to data and class members:

• public — access is open from anywhere, from any class.
• protected — access is allowed within the same package and in subclasses (even if they are in different packages).
• default (package-private) — if the access modifier is not specified, access is allowed only within the current package.
• private — access is only within the class itself.

Example:

public class Example {
    public int publicField;       // accessible everywhere
    protected int protectedField; // accessible within the package and subclasses
    int defaultField;             // accessible only within the package
    private int privateField;     // accessible only within this class
}

These levels help control encapsulation and data security in the application.