What does ?: mean in Java

Question

In the code below:

public static void main(String[] args) {
    String echo = (args.length == 1) ?  "Your name is "+args[0]: "Wrong number of arguments!";
    System.out.println(echo);
}

It will print your name if you give only one argument, otherwise it will warn you with wrong number of arguments, which is pretty clear, but how does ?: operator work here?

It's the "confused face" operator - it means you did not know the term "ternary operator" so were not able to search for it online. — Benjamin Gruenbaum, Sep 07 '14 at 11:16
@BenjaminGruenbaum: I beg to differ! https://www.google.co.uk/search?q=java%20operator - First two hits will give you the name. — Oliver Charlesworth, Sep 07 '14 at 11:17

score 2 · Accepted Answer · answered Sep 07 '14 at 11:16

The ?: operator is called Ternary operator, it is used as follows:

condition ? value_if_true : value_if_false

Your code can be written as:

public static void main(String[] args) {

    String echo = null;
    if(args.length == 1){
        echo = "Your name is " + args[0];
    }else{
        echo = "Wrong number of arguments!";
    }

    System.out.println(echo);

}

score 0 · Answer 2 · answered Sep 07 '14 at 11:16

0

The ternary operator.

a ? b : c

means: b if a is true, otherwise c

answered Sep 07 '14 at 11:16

khelwood

52,115
13
74
94

score 0 · Answer 3 · answered Sep 07 '14 at 11:16

0

It is sort of like an if clause. The first part of this ternary operator is the test statement, and if it evaluates to true it executes the code after ? and if it's not, then it executes after :

answered Sep 07 '14 at 11:16

Franko Leon Tokalić

1,437
2
22
27

What does ?: mean in Java

3 Answers3