Return

Methods can do more than just separate code: they can also return data to the methods that call them.

We know that in Java, all variables have a type (int, char, String, etc.).

Methods have a return type which tells the type of value a method will return.

• This method will return an int value.

• This method does not return any value.

• Every method needs a return type, so this method's return type is void.

The return type determines what a method must return. * If its return type is int, it must return an int value. * If its return type is void, it cannot try to return a value.

Practice Exercise

A method with a void return type can still have a return statement with no value. This just tells the method to end so the program jumps back to the caller.

public static void checkForEven() {
  int x = 0;
  //...
  if (x % 2 == 0) {
    return; //exit this method
  }
  System.out.println("x is not even");
}

However, a void method is not required to have a return statement.

Practice Exercise

The code below generates a compiler error.

public static int compilerError() {
  int x = 0;
  //...
  if (x == 0) {
    return -1;
  }
}

This method must return an int. The compiler sees that it only returns a value when x == 0, so it sees a path through the code where no value is returned. That is illegal.

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