what effects does the abstract class have code example

Example 1: abstract class in java

public abstract class GraphicObject {

   abstract void draw();
}

Example 2: how to create an abstract method in java

abstract class Scratch{
  // cannot be static
    abstract public void hello();
    abstract String randNum();
}

interface Other{
  //all methods in an interface are abstract
    public void bye();
    String randDouble();
}