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Java Program to initialize a HashMap with Lambda Expressions
To initialize a HashMap with Lambda, at first create a HashMpa and use Callable −
HashMap<Integer, Callable<Integer>>map = newHashMap<Integer, Callable<Integer>>()
For key-value pair, you need to initialize them in the following way −
HashMap<Integer, Callable<Integer>>map = newHashMap<Integer, Callable<Integer>>() {
{
put(0, () -> {
return 10;
});
put(1, () -> {
return 20;
});
}
};Example
import java.util.HashMap;
import java.util.concurrent.Callable;
public class Demo {
public static void main(String[] args) throws Exception {
HashMap<Integer, Callable<Integer>>map = newHashMap<Integer, Callable<Integer>>() {
{
put(0, () -> {
return 10;
});
put(1, () -> {
return 20;
});
put(2, () -> {
return 30;
});
put(3, () -> {
return 40;
});
}};
System.out.println(map.get(0).call());
System.out.println(map.get(1).call());
System.out.println(map.get(2).call());
System.out.println(map.get(3).call());
}
}
}Output
10 20 30 40
Updated on: 30-Jul-2019
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