Java 8 Map : compute()
compute()
Map compute() function computes a mapping for the specified key and its current mapped value.
It uses a BiFunction for the mapping.
Syntax :
default V compute(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)
Java8 compute() example
package com.topjavatutorial;
import java.util.HashMap;
import java.util.Map;
public class TestMap5 {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("A", 1);
map.put("B", 2);
map.put("C", 3);
System.out.println(map);
map.compute("A", (k, v) -> (v==null ? 0 : v+1));
System.out.println(map);
map.compute("D", (k, v) -> (v==null ? 0 : v+1));
System.out.println(map);
}
}
Output :
{A=1, B=2, C=3}
{A=2, B=2, C=3}
{A=2, B=2, C=3, D=0}
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