modifier private not allowed here

Java error "modifier private not allowed here" can occur for any of the following reasons:

1. An outer class declared as private like below:

private class OuterClass
{
    //...
}

An outer class only be public or package private not private or protected. So you can write an outer class as below:

public class OuterClass
{
   //...
}

or

class OuterClass
{
   //...
}

This is true for an interface also. An interface can only be public or package not private or protected.


2. An interface method declared as private.

public interface TestInterface
{
   private void method(); // wrong as the interface method is private
}

An interface can contain only public or package private method.

The correct code of the above is:

public interface TestInterface
{
   public void method();
}

or

public interface TestInterface
{
   void method(); // interface method declared as package private
}