[java] What is a Question Mark "?" and Colon ":" Operator Used for?

Two questions about using a question mark "?" and colon ":" operator within the parentheses of a print function: What do they do? Also, does anyone know the standard term for them or where I can find more information on their use? I've read that they are similar to an 'if' 'else' statement.

int row = 10;
int column;
while (row >= 1)
{
    column = 1;
    while(column <= 10)
    {
        System.out.print(row % 2 == 1 ? "<" : "\r>");
        ++column;
    }
    --row;
    System.out.println();
}

This question is related to java operators ternary-operator conditional-operator

The answer is


Also just though I'd post the answer to another related question I had,

a = x ? : y;

Is equivalent to:

a = x ? x : y;

If x is false or null then the value of y is taken.


a=1;
b=2;

x=3;
y=4;

answer = a > b ? x : y;

answer=4 since the condition is false it takes y value.

A question mark (?)
. The value to use if the condition is true

A colon (:)
. The value to use if the condition is false


it is a ternary operator and in simple english it states "if row%2 is equal to 1 then return < else return /r"


Thats an if/else statement equilavent to

if(row % 2 == 1){
  System.out.print("<");
}else{
  System.out.print("\r>");
}

They are called the ternary operator since they are the only one in Java.

The difference to the if...else construct is, that they return something, and this something can be anything:

  int k = a > b ? 7 : 8; 
  String s = (foobar.isEmpty ()) ? "empty" : foobar.toString (); 

Maybe It can be perfect example for Android, For example:

void setWaitScreen(boolean set) {
    findViewById(R.id.screen_main).setVisibility(
            set ? View.GONE : View.VISIBLE);
    findViewById(R.id.screen_wait).setVisibility(
            set ? View.VISIBLE : View.GONE);
}

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