CODEWITHSUNDEEP
java
Sabaspro
Sabaspro

Reputation: 107

what does ":" stands for, in a for function

i have this code, and i would like to know what the ":" mean in the function

Element[][] grid = readFile();
for (Element[] ea : grid) {
    for (Element e : ea)
         System.out.print(e.getChar());
     System.out.println();

Upvotes: 1

Views: 180

Answers (6)

vaisakh
vaisakh

Reputation: 1031

This type of loop is called a 'for-each' loop. The colon (:) is read as 'in'. Basically, this type of for loop is used with collections.

It could be read as:-

for each element x in collection Y{
//do something
}

Here, in each iteration, the element x refers to the respective elements in Collection Y. i.e, in first iteration, x will be Y[0], in second iteration, x will be y[1], so on and so forth till the end.

The advantage is that condition checking and all those stuff need not be written explicitly. It is especially useful when iteration elements in a collection sequentially till the end. This makes iterating over collections quite easier. It is easier than making use of iterators.

In your code, each element of the two dimensional array 'ea' is printed, using a nested for-each loop. Outer loop iterates over each row (a single dimensional array), and inner loop iterates over each element in the respective row.

Refer these:-
For-each loop
Related question in stackoverflow

Upvotes: 1

rtheunissen
rtheunissen

Reputation: 7435

It's simply a divider between the temporary variable and the Iterable or array.
It's called a foreach loop, and basically means:
"For each element ae in Iterable grid, do {...}"

Read more here: The For-Each Loop

Iterable being an array or a list, for example.

Upvotes: 0

Nishant
Nishant

Reputation: 55856

It's a for-each comprehension for Collections and Array. It's same as some languages like Python provide in functionality. So when you see a : in a for loop, read as in. For more details see this http://docs.oracle.com/javase/1.5.0/docs/guide/language/foreach.html

In your case it's like for ea in grid.

Upvotes: 1

Will
Will

Reputation: 20235

When : is used in for, it acts as a for-each loop. Each iteration, the variable after the colon is assigned to the next value in the array.

int[] arr = {1,2,3,4};
for ( arr : num ) {
    System.out.print( num + " " );
}
// prints "1 2 3 4 "

Upvotes: 1

Daniel Murphy
Daniel Murphy

Reputation: 882

In terms of a language equivalent, you can think of it as the word "in". You can read it as "for each Element 'e' in 'ea'".

Here's the documentation on that type of loop: http://docs.oracle.com/javase/1.5.0/docs/guide/language/foreach.html

Upvotes: 4

emory
emory

Reputation: 10891

This is the new enhanced for loop.

You can read it out loud as for each Element ea in grid. It iterates over the elements in grid.

Here is a nice tutorial .

Upvotes: 0

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