this code does not compile successfully because of the error which says update is not an abstract and does not override abstract method validate in line 5 and line 14 class updateinfo implements validateinfo

public interface validateInfo
{
public void validate(String empcode, String password);
}
class updateInfo implements validateInfo
{
public void update()
{
//code to update information of customer
}
public static void main(String a1[])
{
updateInfo o= new updateInfo();
p.update();
System.out.println("Information updated");
}
}

When you implement an interface you need to provide an actual method for each method signature in the interface. It's complaining that it isn't abstract because you didn't do so, and the only way not to do so is in an abstract class.

Provide a Validate method in your updateInfo class.