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How to initialize HashSet values by construction?
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hashsethowinitializevaluesconstruction
Problem
I need to create a
Is there a way to do this in one line of code? For instance, it's useful for a final static field.
Set with initial values.Set h = new HashSet();
h.add("a");
h.add("b");Is there a way to do this in one line of code? For instance, it's useful for a final static field.
Solution
There is a shorthand that I use that is not very time efficient, but fits on a single line:
Again, this is not time efficient since you are constructing an array, converting to a list and using that list to create a set.
When initializing static final sets I usually write it like this:
Slightly less ugly and efficiency does not matter for the static initialization.
Set h = new HashSet<>(Arrays.asList("a", "b"));Again, this is not time efficient since you are constructing an array, converting to a list and using that list to create a set.
When initializing static final sets I usually write it like this:
public static final String[] SET_VALUES = new String[] { "a", "b" };
public static final Set MY_SET = new HashSet<>(Arrays.asList(SET_VALUES));Slightly less ugly and efficiency does not matter for the static initialization.
Code Snippets
Set<String> h = new HashSet<>(Arrays.asList("a", "b"));public static final String[] SET_VALUES = new String[] { "a", "b" };
public static final Set<String> MY_SET = new HashSet<>(Arrays.asList(SET_VALUES));Context
Stack Overflow Q#2041778, score: 1190
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