- 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 TreeMap entrySet() Method
Description
The Java TreeMap entrySet() method is used to return a Set view of the mappings contained in this map. The set's iterator returns the entries in ascending key order. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa.
Declaration
Following is the declaration for java.util.TreeMap.entrySet() method.
public Set<Map.Entry<K,V>> entrySet()
Parameters
NA
Return Value
The method call returns a set view of the mappings contained in this map.
Exception
NA
Getting Set of Mappings of a TreeMap of Integer,Integer Pairs Example
The following example shows the usage of Java TreeMap entrySet() method to get a set of mapping ordered in a ascending order. We've created a TreeMap object of Integer,Integer pairs. Then few entries are added to map and using entrySet() we've retrieved the set of mappings and then printed the same.
package com.tutorialspoint; import java.util.Set; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Integer> treemap = new TreeMap<>(); // populating tree map treemap.put(2, 2); treemap.put(1, 1); treemap.put(3, 3); treemap.put(6, 6); treemap.put(5, 5); // putting values in set Set mapset = treemap.entrySet(); System.out.println("Checking value"); System.out.println("Entry set values: "+mapset); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking value Entry set values: [1=1, 2=2, 3=3, 5=5, 6=6]
Getting Set of Mappings of a TreeMap of Integer,String Pairs Example
The following example shows the usage of Java TreeMap entrySet() method to get a set of mapping ordered in a ascending order. We've created a TreeMap object of Integer,String pairs. Then few entries are added to map and using entrySet() we've retrieved the set of mappings and then printed the same.
package com.tutorialspoint; import java.util.Set; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, String> treemap = new TreeMap<>(); // populating tree map treemap.put(2, "two"); treemap.put(1, "one"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(5, "five"); // putting values in set Set mapset = treemap.entrySet(); System.out.println("Checking value"); System.out.println("Entry set values: "+mapset); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking value Entry set values: [1=one, 2=two, 3=three, 5=five, 6=six]
Getting Set of Mappings of a TreeMap of Integer,Object Pairs Example
The following example shows the usage of Java TreeMap entrySet() method to get a set of mapping ordered in a ascending order. We've created a TreeMap object of Integer,Student pairs. Then few entries are added to map and using entrySet() we've retrieved the set of mappings and then printed the same.
package com.tutorialspoint; import java.util.Set; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Student> treemap = new TreeMap<>(); // populating tree map treemap.put(2, new Student(2, "Robert")); treemap.put(1, new Student(1, "Julie")); treemap.put(3, new Student(3, "Adam")); treemap.put(6, new Student(6, "Julia")); treemap.put(5, new Student(5, "Tom")); // putting values in set Set mapset = treemap.entrySet(); System.out.println("Checking value"); System.out.println("Entry set values: "+mapset); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { if(obj == null) return false; Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking value Entry set values: [1=[ 1, Julie ], 2=[ 2, Robert ], 3=[ 3, Adam ], 5=[ 5, Tom ], 6=[ 6, Julia ]]
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