- Java.util Package Classes
- Java.util - Home
- Java.util - ArrayDeque
- Java.util - ArrayList
- Java.util - Arrays
- Java.util - BitSet
- Java.util - Calendar
- Java.util - Collections
- Java.util - Currency
- Java.util - Date
- Java.util - Dictionary
- Java.util - EnumMap
- Java.util - EnumSet
- Java.util - Formatter
- Java.util - GregorianCalendar
- Java.util - HashMap
- Java.util - HashSet
- Java.util - Hashtable
- Java.util - IdentityHashMap
- Java.util - LinkedHashMap
- Java.util - LinkedHashSet
- Java.util - LinkedList
- Java.util - ListResourceBundle
- Java.util - Locale
- Java.util - Observable
- Java.util - PriorityQueue
- Java.util - Properties
- Java.util - PropertyPermission
- Java.util - PropertyResourceBundle
- Java.util - Random
- Java.util - ResourceBundle
- Java.util - ResourceBundle.Control
- Java.util - Scanner
- Java.util - ServiceLoader
- Java.util - SimpleTimeZone
- Java.util - Stack
- Java.util - StringTokenizer
- Java.util - Timer
- Java.util - TimerTask
- Java.util - TimeZone
- Java.util - TreeMap
- Java.util - TreeSet
- Java.util - UUID
- Java.util - Vector
- Java.util - WeakHashMap
- Java.util Package Extras
- Java.util - Interfaces
- Java.util - Exceptions
- Java.util - Enumerations
- Java.util Useful Resources
- Java.util - Useful Resources
- Java.util - Discussion
java.util.TreeMap.firstEntry() Method
Description
The firstEntry() method is used to return a key-value mapping associated with the least key in this map, or null if the map is empty.
Declaration
Following is the declaration for java.util.TreeMap.firstEntry() method.
public Map.Entry<K,V> firstEntry()
Parameters
NA
Return Value
The method call returns an entry with the least key, or null if this map is empty.
Exception
NA
Example
The following example shows the usage of java.util.TreeMap.firstEntry() method.
package com.tutorialspoint; import java.util.*; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, String> treemap = new TreeMap<Integer, String>(); // populating tree map treemap.put(2, "two"); treemap.put(1, "one"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(5, "five"); System.out.println("Checking first entry"); System.out.println("First entry is: "+ treemap.firstEntry()); } }
Let us compile and run the above program, this will produce the following result.
Checking first entry First entry is: 1=one
java_util_treemap.htm
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