Ternary operator gives "Not a statement" error

Question

Hi below statement throws error . It says "Not a statement"

map.containsKey(1)? someObject.setFlag(true) : map.put(1,"hello");

Is it needed to store the returned value in some variable on the left hand side of the statement?

You are missing a semicolon. p.s. You can reduce `map.containsKey(1) == true` to `map.containsKey(1)`. — Code-Apprentice, Jul 05 '18 at 17:37
Try `map.containsKey(1)`. You don't need to compare a boolean value to true. It is already either true or false. Also no semicolon as above. — Lane Terry, Jul 05 '18 at 17:37
added a semi colon and tried with only map.containsKey(1).. still does not work — tech_questions, Jul 05 '18 at 17:39
@JaredStewart Although that question is related, I don't think the answers are helpful here because the solution is to use an `if` statement. — Code-Apprentice, Jul 05 '18 at 17:44

score 8 · Answer 1 · edited Jul 05 '18 at 17:48

8

You are using the Ternary operator as a statement, not an assignment. In your case, you should use if else

if(map.containsKey(1)) {
    someObject.setFlag(true)
}else{
    map.put(1,"hello");
}

Here is the java docs of Ternary operator.

edited Jul 05 '18 at 17:48

Youcef LAIDANI

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answered Jul 05 '18 at 17:42

Amit Bera

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Code-Apprentice · Answer 2 · 2018-07-05T21:07:42.287

The ternary operator is an expression, not a statement. It is commonly used to set the value of a variable depending on some condition. In this case, you need to assign the result to a variable in order to make it into a statement:

String result = map.containsKey(1) ? someObject.setFlag(true) : map.put(1,"hello");

(Note: You should choose a better variable name.)

I think you will still have problems here because setFlag() probably doesn't return a String. Also, since you are creating side effects, you should replace this with an if statement.

Ternary operator gives "Not a statement" error

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