what does the "?" and ":" sign mean in a line of java code?

Question

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What is a Question Mark “?” and Colon “:” Operator Used for?
Question mark in java code

I am writing codes for a RBG to HSV converter. I have this line:

var d = (r==minRGB) ? g-b : ((b==minRGB) ? r-g : b-r);

i dont really understand what the "?" and the ":" means here.

its javascript. i am writing the rgb to hsv converter in java. — Parvesh, Oct 18 '12 at 14:12
This one too: http://stackoverflow.com/questions/10336899/java-what-is-a-question-mark-and-colon-within-the-parentheses-of-a-prin — assylias, Oct 18 '12 at 14:12
@assylias yes. My question was not quite clear, my mistake. the line of code is from a javascript rgb to hsv converted, trying to write it in java. — Parvesh, Oct 18 '12 at 14:14

score 3 · Answer 1 · answered Oct 18 '12 at 14:12

3

This is the short way to make a condition :

  Condition ? Statment1 : Statement2;

Means

  If (Condition) {Statement1} else {Statement2}

answered Oct 18 '12 at 14:12

Rafik Bari

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how can this answer get upvotes? it's simply wrong. Terinary operators do not work for statements in java – gefei Oct 18 '12 at 14:14

score 2 · Answer 2 · answered Oct 18 '12 at 14:10

2

This is called ternary operator in java.

Based on java tutorial

Another conditional operator is ?:, which can be thought of as shorthand for an if-then-else statement (discussed in the Control Flow Statements section of this lesson). This operator is also known as the ternary operator because it uses three operands.

If first expression results in true, then assign second operand as value, otherwise third operand as value.

answered Oct 18 '12 at 14:10

kosa

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1

@Quoi: Question heading said java, that is why this answer. If question is on javascript, I am sorry! – kosa Oct 18 '12 at 14:15
Ok. I was confused `var` +1. :) – Subhrajyoti Majumder Oct 18 '12 at 14:17

Yogendra Singh · Accepted Answer · 2012-10-18T14:18:40.640

2

Its Ternary Operator:

C = condition? A : B

is equivalent to

 if (condition){
  C=  A;
 } else{
   C=  B;
 }

It also support nesting i.e. C = condition1? A : condition2?D:E, which is equivalent to

 if (condition1){
   C=  A;
 } else if (condition2){
   C=  D;
 } else{
   C= E;
 }

edited Oct 18 '12 at 14:18

answered Oct 18 '12 at 14:11

Yogendra Singh

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score 1 · Answer 4 · answered Oct 18 '12 at 14:11

1

It means

if (r==minRGB)
  d = g-b
else
  if(b==minRGB)
     d=r-g
  else
    d=b-r

answered Oct 18 '12 at 14:11

mat

1,645
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Rohit Jain · Answer 5 · 2012-10-18T14:16:12.267

0

Its called ternary operator (?:): -

System.out.println(condition? value1 : value2);

The above expression is evaluated like: -

if (condition) {
    System.out.println(value1); 
} else {
    System.out.println(value2);
}

edited Oct 18 '12 at 14:16

answered Oct 18 '12 at 14:11

Rohit Jain

209,639
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score 0 · Answer 6 · answered Oct 18 '12 at 14:11

0

In c-based languages, it means: ? :

Its short-hand for an if-else, basically.

answered Oct 18 '12 at 14:11

CodeChimp

8,016
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score 0 · Answer 7 · answered Oct 18 '12 at 14:12

0

it work similar to if than else

if (r==minRGB)
    d = g-b;
}else{
    if  (b==minRGB)
    {
        d = r-g;
    }else{
        d = b-r;
    }
}

answered Oct 18 '12 at 14:12

Minion91

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what does the "?" and ":" sign mean in a line of java code?

7 Answers7