Java Tutorial - Java ternary operator

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The ? operator is a ternary (three-way) operator.

Java ternary operator is basically a short form of simple if statement.

Syntax

The ? has this general form:

expression1 ? expression2 : expression3

expression1 can be any expression that evaluates to a boolean value. If expression1 is true, then expression2 is evaluated. Otherwise, expression3 is evaluated.

The expression evaluated is the result of the ? operation. Both expression2 and expression3 are required to return the same type, which can't be void.

Here is an example of ? operator:

 
public class Main {
  public static void main(String[] argv) {
    int denom = 10;
    int num = 4;/* ww w.java2s.  co m*/
    double ratio;
    ratio = denom == 0 ? 0 : num / denom;
    System.out.println("ratio = " + ratio);
  }
}

The output:

Example

Here is another program that demonstrates the ? operator. It uses it to obtain the absolute value of a variable.

 
public class Main {
  public static void main(String args[]) {
    int i, k;//from w  w  w .  j a  va 2s  . c  o  m
    i = 10;
    k = i < 0 ? -i : i; 
    System.out.print("Absolute value of ");
    System.out.println(i + " is " + k);
    i = -10;
    k = i < 0 ? -i : i; 
    System.out.print("Absolute value of ");
    System.out.println(i + " is " + k);
  }
}

The output generated by the program is shown here:

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