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I would like to create a
public static final LinkedMap myMap;
Somewhere I found something similar for Maps:
public class Test {
private static final Map<Integer, String> MY_MAP = createMap();
private static Map<Integer, String> createMap() {
Map<Integer, String> result = new HashMap<Integer, String>();
result.put(1, "one");
result.put(2, "two");
return Collections.unmodifiableMap(result);
}
}
But I cannot apply the 'unmodifiableMap' method it to a LinkedMap. Can anybody help me? Is it possible at all?
284
The Static Initializer for a Static HashMap We can also initialize the map using the double-brace syntax: Map<String, String> doubleBraceMap = new HashMap<String, String>() {{ put("key1", "value1"); put("key2", "value2"); }};
We can use Java 8 Stream to construct static maps by obtaining stream from static factory methods like Stream.
A Static Initialization Block in Java is a block that runs before the main( ) method in Java. Java does not care if this block is written after the main( ) method or before the main( ) method, it will be executed before the main method( ) regardless.
The most popular workaround is almost certainly a Guava ImmutableMap. (Disclosure: I contribute to Guava.)
Map<Integer, String> map = ImmutableMap.of(
1, "one",
2, "two");
or
ImmutableMap<Integer, String> map = ImmutableMap
.<Integer, String> builder()
.put(1, "one")
.put(2, "two")
.build();
Without other libraries, the only workaround other than the one you've written is
static final Map<Integer, String> CONSTANT_MAP;
static {
Map<Integer, String> tmp = new LinkedHashMap<Integer, String>();
tmp.put(1, "one");
tmp.put(2, "two");
CONSTANT_MAP = Collections.unmodifiableMap(tmp);
}
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