JAVA Linked List How to loop through with a for loop?

Question

Hello I am trying to create a for loop that loops through the linked list. For each piece of data it will list it out individually. I am trying to learn linked list here, so no Array suggestions please. Anyone know how to do this?

Example Output:

1. Flight 187
2. Flight 501

---

CODE I HAVE SO FAR BELOW:

public static LinkedList<String> Flights = new LinkedList<String>();
public flightinfo(){
String[] flightNum = {"187", "501"};
 for (String x : flightNum)
 Flights.add(x);
 for (???)
}

• Thomas Owens: Why are you iterating over the linked list? I'm confused by what you are trying to do. Right now, you have a LinkedList and an array of Strings, and you are iterating over that array of Strings to add them to a LinkedList. I don't understand what your end goal is.

Answer 1

Just use the enhanced for-loop, the same way you'd do it with an array:

for(String flight : flights) {
 // do what you like with it
}

Answer 2

If I understand you correctly, you have to get a reference to the List's iterator and use that to cycle through the data:

ListIterator iterator = Flights.iterator(); 
while (iterator.hasNext()){
 System.out.print(iterator.next()+" "); 
}

Answer 3

for(String y : Flights) {
//...
}

The same way as arrays, since it inherits from Iterable<T>

As pointed out by @Cold Hawaiian this only works for Java>= 5.0

If pre 5.0 use:

ListIterator<String> iter = Flights.iterator();
while(iter.hasNext()) {
 String next = iter.next();
 // use next
}

• allencoded: This worked I copied the first for loop which was my mistake as it didn't teach me anything. Now I get it though!! Thanks

Answer 4

You should use a ListIterator (see Java API for more information).

Answer 5

If you have distinct values in the linked list , this would work :

for(Iterator<String> i = Flights.listIterator(); i.hasNext();){
 String temp = i.next();
 System.out.println(Flights.indexOf(temp)+1+". Flight "+temp );
}

If you do not have distinct values in the linked list, this would work :

int i=0;
for(Iterator<String> iter = Flights.listIterator(); iter.hasNext();i++){
 String temp = iter.next();
 System.out.println(i+1+". Flight "+temp );
}

Hope this helps.

Answer 6

With Java8 Collection classes that implement Iterable have a forEach() method. With forEach() and lambda expressions you can easily iterate over LinkedList

flights.forEach(flight -> System.out.println(flight));

Answer 7

while(!flights.isEmptry) {
 System.out.println(flights.removeFirst());
}