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Is there a Utility method somewhere that can do this in 1 line? I can't find it anywhere in Collections, or List.
public List<String> stringToOneElementList(String s) { List<String> list = new ArrayList<String>(); list.add(s); return list; } I don't want to re-invent the wheel unless I plan on putting fancy rims on it.
Well... the type can be T, and not String. but you get the point. (with all the null checking, safety checks...etc)
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ArrayList cloned = new ArrayList(collection c); where c is the collection containing elements to be added to this list. Approach: Create a list to be cloned. Clone the list by passing the original list as the parameter of the copy constructor of ArrayList.
Using Collections. singletonList() Method [ Immutable List ] This is simplest and recommended method to create immutable List with single element inside it. The list created with this method is immutable as well, so you are sure that there will not be any more elements in list, at any condition.
ArrayList<String> list = new ArrayList<String>(); list. add("A"); list. add("B"); list. add("C");
List The easiest way, that I know of, is to create a fixed-size single element List with Arrays.asList(T...) like
// Returns a List backed by a varargs T. return Arrays.asList(s); List If it needs vary in size you can construct an ArrayList and the fixed-sizeList like
return new ArrayList<String>(Arrays.asList(s)); and (in Java 7+) you can use the diamond operator <> to make it
return new ArrayList<>(Arrays.asList(s)); Collections can return a list with a single element with list being immutable:
Collections.singletonList(s) The benefit here is IDEs code analysis doesn't warn about single element asList(..) calls.
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