The Map.getOrDefault(Object key, V defaultValue) method in Java 8 is a convenience default method to return the value for a given key. If the map does not contain a mapping for the key, then it returns the default value.
This method can be particularly useful in situations where you’re working with a map and need to fetch a value for a key, but aren’t sure if the key exists in the map. It helps you handle these scenarios without a need to write extra conditional code to check if the key is present (i.e., using containsKey(Object key)) before trying to get the value.
Here’s a common use case without getOrDefault():
Map<String, Integer> map = new HashMap<>();
// fill map...
Integer value;
if (map.containsKey("key")) {
value = map.get("key");
} else {
value = -1;
}
Here’s a basic example of how to use getOrDefault():
package org.kodejava.util;
import java.util.HashMap;
import java.util.Map;
public class MapGetOrDefaultExample {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);
map.put("C", 3);
// Get a value of the key "A". It will return value 1 as
// "A" is present in the map.
Integer value = map.getOrDefault("A", -1);
System.out.println("Value: " + value);
// Try to get a value of the key "Z". As "Z" is not present
// in the map, it will return the default value -1.
value = map.getOrDefault("Z", -1);
System.out.println("Value: " + value);
}
}
In this example, “Value: 1” and then “Value: -1” will be printed in the console. In the first case, the key “A” is in the map, so the associated value 1 is returned. In the second case, the key “Z” does not exist in the map, so the default value of -1 is returned.
- How do I create a servlet filter to make secure cookies? - April 18, 2024
- How do I configure secure cookies using web.xml? - April 18, 2024
- How do I create a table with multiple header in iText 8? - March 16, 2024