is it needed for abstract class have one method as an abstract code example

Example 1: write a program in which an abstract class is being defined containg an abstract method omputer(int a, int b) and a non abstract method as well

abstract class Sum{
   
   public abstract int compute(int a, int b);
   public void disp(){
	System.out.println("Method of class Sum");
   }
}
class Demo extends Sum{

   public int compute(int a, int b){
	return a+b;
   }
   public static void main(String args[]){
	Sum obj = new Demo();
	System.out.println(obj.compute(3, 7));
	obj.disp();
   }
}

Example 2: can abstract class have implementation java

abstract classes have no implementation of functions methods inside it which declared as abstract methods. classes which are inheriting it have to overriden it. and final absract class can not be overriden