Whether the outer class directly access private members in a Java-based application?

 In the context of Salesforce, an outer class cannot directly access the private members. This behavior is because of an access control mechanism of Java and the principle of encapsulation.

Encapsulation is a fundamental concept in the context of object-oriented programming which involves bundling the data and methods that can operate on the data into a single unit and also can control the access to that unit through access modifiers such as public, private, and protected.

Here is an example given of this concept:-
Public class OuterClass {
    Private int outerPrivateVar = 10;
    Public void outerPublicMethod() {
        InnerClass innerObj = new InnerClass();
        // Cannot access innerPrivateVar directly
        // innerObj.innerPrivateVar; // This line would cause a compilation error
        innerObj.innerPublicMethod(); // Can access public method of inner class
    }
    Private class InnerClass {
        Private int innerPrivateVar = 20;
        Private void innerPrivateMethod() {
            System.out.println(“Inner private method called.”);
        }
        Public void innerPublicMethod() {
            System.out.println(“Inner public method called.”);
            System.out.println(“Accessing outer private variable from inner class: “ + outerPrivateVar);
        }
    }
}