java: is else necessary after if else if statements?

Question

I thought else at the end of if{} else if{} else if{}

is not necessary in java but unless I put it in the code does not work. why is this?

Answer 1

It's not required. If you are getting an error when you omit it, please post the code that gives you the error.

Answer 2

This compiles and runs for me:

public class ElseIfTest
{
    public static void main(String [] args)
    {
        if (args.length == 0)
        {
            System.out.println("zero args");            
        }
        else if (args.length == 1)
        {
            System.out.println("one arg");            
        }
        else if (args.length == 2)
        {
            System.out.println("two args");            
        }
    }
}

No trailing else required.

Answer 3

The compiler may complain if your if-statements are inside a function that has a return value and you don't return a value for the last "else" part.

Example:

String returnSomething(int i)
{
      if (i < 0)
          return "negative";
      else if (i > 0)
          return "positive";
      else if (i == 0)
          return "zero";
}

The compiler will complain because it thinks that there's a missing return statement if none of the if-conditions are true.

You can fix that by either adding an else at the end, or replacing the last else-if with an else (but you have to make sure that the condition is always true).

So, it becomes

String returnSomething(int i)
{
      if (i < 0)
          return "negative";
      else if (i > 0)
          return "positive";
      else // it's not < 0 , and not > 0, it is definitely 0
          return "zero";
}