Complex Conditionals and Unreachable Statements

Question

I am very new to Java and am having some trouble. I feel like this an easy fix. Basically, I am looking to return a statement if two criteria are met. Below is my attached code.

boolean Windy = false;

if (Windy = true) 
  return "It is Windy";
else 
  return "Not Windy";

if (temperature < 30);
{return "Too Windy or Cold! Enjoy watching the weather through the window";

Additional errors are being thrown after I try to alter the script, claiming a return statement is required.

Answer 1

Your code contains several mistakes:

1. The = in Windy = true should be a == instead. = is to assign something, and == is to check for equality.
2. Because your first if (Windy = true) return "It is Windy"; else return "Not Windy"; will always return one of the two, the rest of your code below it is unreachable and will never be executed.
3. Even if it was reachable, the trailing semi-colon at the if (temperature < 30); should be removed.
4. The {}-block inside your method isn't necessary.

I think this is what you are looking for with your code:

boolean windy = false;

if(windy){
  return "It is Windy";
} else if(temperature < 30){
  return "Too Windy or Cold! Enjoy watching the weather through the window";
} else{
  return "Not Windy";
}

Of course, setting windy to false hard-coded kinda makes the first check impossible to reach as well. But I assume it's just your example code and in your actual code you retrieve the windy as class variable or method parameter.

In addition, since windy itself is a boolean, the == true is redundant and just if(windy) would be enough.

PS: Variable names in Java are best practice to be camelCase, so use windy instead of Windy in this case.
I've also added the brackets around the if/else-if/else statements. They aren't required and you can leave them out if you really prefer, but it's easier to modify code without making errors later on.

Answer 2

OK, I checked your image (what I usually don't do) and spotted several issues in your code.

public static String getWeatherAdvice(int temperature, String description)
{
  { // REMOVE THIS BRACKET
    if ( Windy = true) // = signifies an assigning a value, not a comparison. Use ==
      return "It is Windy";
    else
      return "Not Windy";

    if ( temperature < 30 ); // Since the above if-else will always return a value, this
    // code can not be reached. Put this if before the previous if-else. Also: remove the ; after the if statement, otherwise, it ends the if, and the return statement might be triggered.
    { // don't put this bracket if you have a ; after the if
      return "Too windy ... ";
    } // don't put this bracket if you have a ; after the if
  } // REMOVE THIS BRACKET
}

A corrected version of your code (could be):

public static String getWeatherAdvice(int temperature, String description)
{
   if ( temperature < 30 )
    { 
      return "Too windy ... ";
    } 

    if ( Windy == true) // can also be written as: if ( Windy ) 
      return "It is Windy";
    else
      return "Not Windy";    
}

Answer 3

You can compare criteria using "&&" = and "||" = or:

if (Windy && temperature < 30) {
return "it's windy and temperature is <30";
} else if (!Windy && temperature > 30) {
return "Not Windy";
}