In this short article, we will discuss how to check if the Map is empty or null in Java. Let's create a standard utility method to check if the Map is empty or null in Java.
Check if Map is Empty or Null in Java - Utility Methods
- isNullOrEmptyMap(Map, ?> map) - Return true if the supplied Map is null or empty. Otherwise, return false.
- isNotNullOrEmptyMap(Map, ?> map) - Return true if the supplied Map is not null or not empty. Otherwise, return false.
1. isNullOrEmptyMap(Map, ?> map)
Return true if the supplied Map is null or empty. Otherwise, return false.
public static boolean isNullOrEmptyMap(Map << ? , ? > map) {
return (map == null || map.isEmpty());
}
2. isNotNullOrEmptyMap(Map, ?> map)
Return true if the supplied Map is not null or not empty. Otherwise, return false.
public static boolean isNotNullOrEmptyMap(Map << ? , ? > map) {
return !isNullOrEmptyMap(map);
}
Complete Example
Here is a complete example to test the above utility methods:
package net.javaguides.lang;
import java.util.HashMap;
import java.util.Map;
public class MapNullOrEmptyExample {
public static void main(String[] args) {
// return true
System.out.println(isNullOrEmptyMap(null));
System.out.println(isNullOrEmptyMap(new HashMap < > ()));
Map < String, String > map = new HashMap < > ();
map.put("key1", "value1");
map.put("key2", "value2");
// return true
System.out.println(isNotNullOrEmptyMap(map));
// return false
System.out.println(isNullOrEmptyMap(map));
}
public static boolean isNullOrEmptyMap(Map << ? , ? > map) {
return (map == null || map.isEmpty());
}
public static boolean isNotNullOrEmptyMap(Map << ? , ? > map) {
return !isNullOrEmptyMap(map);
}
}
Output:
true
true
true
false
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