See the javadoc

of List

list.get(0);

or Set

set.iterator().next();

and check the size before using the above methods by invoking isEmpty()

!list_or_set.isEmpty()

Its always advised to use Iterators or ListIterator to iterate through a list. Using the list size as reference does not workout when you are modifying the list data (removing or inserting elements).

Iterator - allow the caller to iterate through a list in one direction and remove elements from the underlying collection during the iteration with well-defined semantics

You can use a ListIterator to iterate through the list. A ListIterator allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the iterator's current position in the list. You can refer the below example.

ArrayList<String> list = new ArrayList<String>();
    ListIterator<String> iterator = list.listIterator();
    while(iterator.hasNext()){
        System.out.println(iterator.next());
        ...
        ...
        System.out.println(iterator.previous());
        if(!iterator.hasPrevious()){
            System.out.println("at start of the list");
        }else if(!iterator.hasNext()){
            System.out.println("at end of the list");
        }

    }

This is just an example showing the usage of a ListIterator, please analyze what your requirement is and implement as required.

The ArrayList has a method size that returns the size of the list, and a get method to get the element stored at a particular index.

So your for loop could look like:

for(int k=0; k < al.size(); k++) {
    System.out.println("elements are" + al.get(k));
}

Or if you want you could loop through each element without an index:

for(String text : al) {
    System.out.println("elements are" + text);
}

If you want to use streams with java8, you could also do:

al.stream().forEach(System.out::println);

If you are interested, there's another answer that also talks about looping through lists in java.

Regarding the heading of your question:

get first and last element in ArrayList in Java

It should be pretty simple:

mimeList.get(0); // To get first
mimeList.get(mimeList.size()-1); //to get last

And regarding your if condition :

if(!(i==0 || i==mimeList.size()-1))

As you phrased it like:

if the element in mimeList is first or last it will go in else condition other wise in if condition

I used ! in if condition. Otherwise below is pretty cool:

if((i>0) && (i!=mimeList.size()-1))

You should take a look at this answer because this is exactly what you want: https://stackoverflow.com/a/8882358/9016740

You can access the first element of an ArrayList by using the get(index) method as such:

List<String> resultList = new ArrayList<String>();
List<Object[]> listObj = (List<Object[]>)query.getResultList();
Object[] firstObjArray = listObj.get(0);
resultList.add(((String)firstObjArray[0]));
resultList.add(((String)firstObjArray[1]));

One way is to use a Stream and map each of the inner arrays to its first element:

List<String> firstElements = yourList.stream()
                                     .map(x -> x[0].toString()) // you might need toString() here if your array is an Object[]
                                     .collect(Collectors.toList());

If you would like an array of strings instead:

String[] firstElements = yourList.stream()
                                     .map(x -> x[0].toString()) // you might need toString() here if your array is an Object[]
                                     .toArray(String[]::new);

I also suggest you to not use nested arrays like this. You should create a class with the properties you want to store and create a List of your class.

Write a Comparator.

Comparator<MyType> myOrder = new Comparator<MyType>() {
    public int compare(MyType a, MyType b) {
         return (b.booleanField() ? 1 : 0) - (a.booleanField() ? 1 : 0);
    }
}

Sort using this comparator.

Collections.sort(myList, myOrder);

See Collections.sort

Edit

So it seems that what you're actually asking for is to move just one matching element to the front of your list. That ought to be pretty easy.

Find the index of the element you want to move:

int foundIndex = -1;
for (int i = 0; i < tripList.size(); ++i) {
    if (tripList.get(i).freeCancellation) {
        foundIndex = i;
        break;
    }
}

If you find such an element, and it is not already at the start, move it to the start:

if (foundIndex > 0) {
    tripList.add(0, tripList.remove(foundIndex));
}