Skip if conditions when a flag is false

Question

I have several independent if conditions and in each condition i will evaluate a boolean variable value either true or false.

if the boolean variable value gets false in the first if condition then how can i skip the rest of all conditions.

private static boolean isRecommended(Fruit fruit) {
    boolean isRecommended = true;

    if(fruit.weight > 2){
        isRecommended = false;
    }
    if(!"red".equals(fruit.color)){
        isRecommended = false;
    }
    if(!"sweet".equals(fruit.taste)){
        isRecommended = false;
    }
    if(!fruit.isPerishable){
        isRecommended = false;
    }

    return isRecommended;
}

if the first if() condition is executed then is it possible to return the value. I know in the loops we can use continue keyword to skip the remainder of the loop execution. How can we achieve something similar here.

Update:

i do not mean exactly on the first if() condition, if any of the if() condition is executed then what is best way of skipping the rest of the conditions like continue does in loop

Answer 1

    private static boolean isRecommended(Fruit fruit) {
    while(true)
    {
      boolean isRecommended = true;

      if(fruit.weight > 2){
          isRecommended = false;
          break;
      }
      if(!"red".equals(fruit.color)){
          isRecommended = false;
          break;
      }
      if(!"sweet".equals(fruit.taste)){
          isRecommended = false;
          break;
      }
      if(!fruit.isPerishable){
          isRecommended = false;
          break;
      }
    }
    return isRecommended;
}

Answer 2

I have found another solution, that is the usage of label blocks with break statement. Below is the code

private static boolean isRecommended(Fruit fruit) {
    boolean isRecommended = true;

    labelA:
    {
        if(fruit.weight > 2){
            isRecommended = false;
            break labelA;
        }
        if(!"red".equals(fruit.color)){
            isRecommended = false;
            break labelA;
        }
        if(!"sweet".equals(fruit.taste)){
            isRecommended = false;
            break labelA;
        }
        if(!fruit.isPerishable){
            isRecommended = false;
        }
    }
    return isRecommended;


}

Answer 3

Wrap the rest of the if statements in an else statement:

private static boolean isRecommended(Fruit fruit) {
    boolean isRecommended = true;

    if(fruit.weight > 2){
        isRecommended = false;
    } else {
        if(!"red".equals(fruit.color)){
            isRecommended = false;
        }
        if(!"sweet".equals(fruit.taste)){
            isRecommended = false;
        }
        if(!fruit.isPerishable){
            isRecommended = false;
        }
    }

    return isRecommended;
}

p.s. I highly recommend using spaces rather than tabs for indenting. Tabs often do not port to other editors or environments they way you want.

Answer 4

For a general solution you could use else if:

if(fruit.weight > 2){
    isRecommended = false;
}
else if(!"red".equals(fruit.color)){
   //etc...
}

But in your specific example you can just use boolean logic:

return !(
   fruit.weight > 2 ||
   !"red".equals(fruit.color) ||
   !"sweet".equals(fruit.taste) ||
   !fruit.isPerishable
);

You could use your IDE to refactor the logic of this expression by applying De Morgan's laws. Most decent IDEs can do this for you with a few keystrokes.

Answer 5

return fruit.weight <= 2 
    && "red".equals(fruit.color) 
    && "sweet".equals(fruit.taste)
    && fruit.isPerishable;

Answer 6

Just put a return false in your first conditional.

Answer 7

The simple answer is to return within the if blocks, rather than setting a value. However, that's not exactly scalable, and returning within the blocks increases code complexity.

The complicated, but more flexible answer, is to create an interface that allows you to implement custom logic.

interface RecommendationFilter<T>
{
    boolean recommend(T item);
}

And then, in some implementation, one can use a bunch of generically loaded RecommendationFilters to loop through.

class FruitChecker
{
    private final Set<RecommendationFilter<Fruit>> filters = ...;

    public boolean isRecommended(Fruit fruit)
    {
        boolean recommended = true;

        for (RecommendationFilter<Fruit> filter : filters)
        {
            if ( ! filter.recommend(fruit))
            {
                recommended = false;
                break;
            }
        }

        return recommended;
    }
}

This idea scales up pretty well, and it enables some pretty interesting implementations.

Answer 8

The tests will stop at the first not verified.

private static boolean isRecommended(Fruit fruit) {
    return 
            fruit.weight <= 2
            && "red".equals(fruit.color)
            && "sweet".equals(fruit.taste)
            && fruit.isPerishable
    ;
}

Answer 9

You can condense it like this, by using multiple return statements that will return early and skip the rest. For added brevity I also removed the unneeded curly braces.

private static boolean isRecommended(Fruit fruit) {
    if(fruit.weight > 2)
        return false;
    if(!"red".equals(fruit.color))
        return false;
    if(!"sweet".equals(fruit.taste))
        return false;
    if(!fruit.isPerishable)
        return false;
    return true;
}

Answer 10

if the first if() condition is executed then is it possible to return the value.

Isn't that just it?

if(fruit.weight > 2){
    return false; // etc.
}

Or am I misunderstanding your question?

Answer 11

You can just write

return isRecommended;

inside your ifs. return can be used multiple times.