Java syntax (For) not included

Question

for (int u: adjList.get(v))
{ 
    instructuion 
}

While processing an algorithm, I came across this Java syntax of the "For" loop that I can't figure out. I know that usually it is used like this:

for (int i=0; i < 6; i++) {
    instructuion 
}

What intrigues me here is the ":" in int u: adjList.get(v). I know perfectly well that adjList is a list and u a variable of type integer.

I searched many sites, but none of them gave details on this syntax.

score 0 · Answer 1 · answered Dec 29 '22 at 09:14

The syntax "for-each loop" is used to iterate over a collection of items. In this example, the loop is saying: "for each item of type int in the list adjList.get(v), execute the instruction". It is equivalent to writing a traditional for loop like the one you provided.

For example, the following code will print out the items in the list adjList.get(v):

for (int u: adjList.get(v)) {
    System.out.println(u);
}

score 0 · Answer 2 · answered Dec 29 '22 at 09:20

Yes it is called for-each loop. Let me give you an easy example In the code below we mean that, for each number inside the numbers array.

int numbers[]={33,3,4,5}
// for each number inside the numbers array
for(int number : numbers){
   System.out.println(number);
}

Java syntax (For) not included

2 Answers2