内部类可以用public修饰吗？下面代码报错

package fgdg;

     public interface Shape {

public void paint();

     }

    public class Painter {

        private class InnerShape implements Shape{

public void paint(){

System.out.println("painter paint() method");

}

}

public Shape getShape(){

return new InnerShape();

}   

        public static void main(String []args){

Painter painter = new Painter();

Shape shape = painter. getShape();

shape.paint();

}

     }