Java TreeMap - firstEntry() Method
The java.util.TreeMap.firstEntry() method returns a key-value mapping associated with the least key in this map, or null if the map is empty.
Syntax
public Map.Entry<K,V> firstEntry()
Here, K and V are the type of key and value respectively maintained by the container.
Parameters
No parameter is required.
Return Value
Returns an entry with the least key, or null if this map is empty.
Exception
NA.
Example:
In the example below, the java.util.TreeMap.firstEntry() method returns the key-value mapping associated with the least key in the given map.
import java.util.*;
public class MyClass {
public static void main(String[] args) {
//creating a treemap
TreeMap<Integer, String> MyMap = new TreeMap<Integer, String>();
//populating the map
MyMap.put(102, "John");
MyMap.put(103, "Marry");
MyMap.put(101, "Kim");
MyMap.put(104, "Jo");
MyMap.put(105, "Sam");
//printing the map
System.out.println("MyMap contains: " + MyMap);
//printing the key-value mapping for the least key
System.out.println("Mapping for least key is: " + MyMap.firstEntry());
}
}
The output of the above code will be:
MyMap contains: {101=Kim, 102=John, 103=Marry, 104=Jo, 105=Sam}
Mapping for least key is: 101=Kim
❮ Java.util - TreeMap
