is it necessary for abstract class to have abstract method

1An abstract method is the method which does’nt have any body. 
2Abstract method is declared with
3keyword abstract and semicolon in place of method body.
4
5  public abstract void <method name>();
6Ex : public abstract void getDetails();
7It is the responsibility of subclass to provide implementation to 
8abstract method defined in abstract class

1Abstract classes CAN have non-abstract methods. 

1No, abstract class can have zero abstract methods.
2

1No, abstract class can have zero abstract methods.

1abstract class Sum{
2   
3   public abstract int compute(int a, int b);
4   public void disp(){
5	System.out.println("Method of class Sum");
6   }
7}
8class Demo extends Sum{
9
10   public int compute(int a, int b){
11	return a+b;
12   }
13   public static void main(String args[]){
14	Sum obj = new Demo();
15	System.out.println(obj.compute(3, 7));
16	obj.disp();
17   }
18}

1Yes, we can. An abstract class can have both abstract and non-abstract methods