Syntax error on token "else" — how on earth?

Question

I'm learning Java the classic way — by playing around with Karel.

But I seem to have encountered a simple problem I can't solve even with the help of Google.

I'm getting an error in Eclipse saying there's a syntax error on the token "else", and that I should delete it.

How come? The syntax in the code block above the else statement is identical.

Here's my code:

public void run() {

    putBeeper();
    if(beepersPresent()){

        move();

    } while(frontIsClear()){
        move();
        putBeeper();
    } else if(facingEast()){

        turnLeft();
        move();

    }
        }

Answer 1

Your else matches while, not if. Not entirely clear what you are trying to do there.

Answer 2

Probably:

while(frontIsClear())

should be

else if(frontIsClear())

Answer 3

What exactly are you trying to do here?

while(frontIsClear()){
        move();
        putBeeper();
    } else if(facingEast()){

        turnLeft();
        move();

While this.. else if that? Not possible.

Answer 4

Because you're trying to say while() { } else {

Why else?

(Yes, I did just do that.)

Answer 5

The else statement has to follow immediatly after the if, you have a while loop between them.

Since this was downvoted, more formal the relevant section of Java Language Specification

14.9 The if Statement The if statement allows conditional execution of a statement or a conditional choice of two statements, executing one or the other but not both.

IfThenStatement:
        if ( Expression ) Statement

IfThenElseStatement:
        if ( Expression ) StatementNoShortIf else Statement

IfThenElseStatementNoShortIf:
        if ( Expression ) StatementNoShortIf else StatementNoShortIf

The Expression must have type boolean or Boolean, or a compile-time error occurs.

Answer 6

You put your else after a while, this is indeed a syntax error

Try that:

public void run() {
    putBeeper();
    if(beepersPresent()){
        move();
    } 
    while(frontIsClear()){
        if (facingEast()) {
            turnLeft();
        }
        move();
        putBeeper();
    }
}

Answer 7

Really quite simple.

Your if lasts between the { and }. The else has to be exactly afterwards.

Remove the } near the while and put it somewhere else and you should be ok.