Short form for Java if statement

Question

I know there is a way for writing a Java if statement in short form.

if (city.getName() != null) {
    name = city.getName();
} else {
    name="N/A";
}

Does anyone know how to write the short form for the above 5 lines into one line?

Answer 1

The way to do it is with ternary operator:

name = city.getName() == null ? city.getName() : "N/A"

However, I believe you have a typo in your code above, and you mean to say:

if (city.getName() != null) ...

Answer 2

To avoid calling .getName() twice I would use

name = city.getName();
if (name == null) name = "N/A";

Answer 3

You can write if, else if, else statements in short form. For example:

Boolean isCapital = city.isCapital(); //Object Boolean (not boolean)
String isCapitalName = isCapital == null ? "" : isCapital ? "Capital" : "City";      

This is short form of:

Boolean isCapital = city.isCapital();
String isCapitalName;
if(isCapital == null) {
    isCapitalName = "";
} else if(isCapital) {
    isCapitalName = "Capital";
} else {
    isCapitalName = "City";
}

Answer 4

You can remove brackets and line breaks.

if (city.getName() != null) name = city.getName(); else name = "N/A";

---

You can use ?: operators in java.

Syntax:

Variable = Condition ? BlockTrue : BlockElse;

So in your code you can do like this:

name = city.getName() == null ? "N/A" : city.getName();

---

Assign condition result for Boolean

boolean hasName = city.getName() != null;

---

EXTRA: for curious

In some languages based in JAVA like Groovy, you can use this syntax:

name = city.getName() ?: "N/A";

You can do this in Groovy because if you ask for this condition:

if (city.getName()) {
    //returns true if city.getName() != null
} else {
    //returns false if city.getName() == null
}

So the operator ?: assign the value returned from the condition. In this case, the value of city.getName() if it's not null.

Answer 5

in java 8:

name = Optional.ofNullable(city.getName()).orElse("N/A")

Answer 6

I'm always forgeting how to use the ?: ternary operator. This supplemental answer is a quick reminder. It is shorthand for if-then-else.

myVariable = (testCondition) ? someValue : anotherValue;

where

• () holds the if
• ? means then
• : means else

It is the same as

if (testCondition) {
    myVariable = someValue;
} else {
    myVariable = anotherValue;
}