Unlike a "regular" class, an inner class can be private or protected. If you don't want outside objects to access the inner class, declare the class as private:
Example
class OuterClass {
int x = 10;
private class InnerClass {
int y = 5;
}
}
public class Main {
public static void main(String[] args) {
OuterClass myOuter = new OuterClass();
OuterClass.InnerClass myInner = myOuter.new InnerClass();
System.out.println(myInner.y + myOuter.x);
}
}
If you try to access a private inner class from an outside class (MyMainClass), an error occurs:
Main.java:13: error: OuterClass.InnerClass has private access in OuterClass
OuterClass.InnerClass myInner = myOuter.new InnerClass();
^
OuterClass.InnerClass myInner = myOuter.new InnerClass();
^
Practice Excercise Practice now