what happens if both superclass and subclass have a field with same name?

Sub class field will hide the Super class field. Hidden super class field in sub class can be accessed using super keyword.
Example

class Show {
	int num = 150;
}
 
class Display extends Show {
	int num = 250;
 
	public void display(){
	    System.out.println("num of subclass = " + num);
		System.out.println("num of super class = " + super.num);
	}
}
 
public class Main {
	public static void main(String args[]){
		//create Show class object.
		Display obj = new Display();
		//method call
		obj.display();
	}
}

Output

num of subclass = 250      
num of super class = 150

Java interview questions on Inheritance