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I was just wondering if it is possible to define the contents of a Map Object on initialisation.
For example, an array can be created, as:
new String[] {“apples”, “bananas”, “pears”}
So, I was wondering if there is something similar we can do for maps.
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Map map = new HashMap(); map. put("key1", "value 1"); String element1 = (String) map. get("key1"); Notice that the get() method returns a Java Object , so we have to cast it to a String (because we know the value is a String).
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"); }};
A Map is an object that maps keys to values. A map cannot contain duplicate keys: Each key can map to at most one value. It models the mathematical function abstraction.
You can, sort of, using this syntax trick:
Map<String,String> map = new HashMap<String,String>() {{
put("x", "y");
put("a", "b");
}};
Not very pleasant, though. This creates an anonymous subclass of HashMap, and populates it in the instance initializer.
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