- Java.util Package Classes
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- Java.util - ArrayDeque
- Java.util - ArrayList
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- 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 WeakHashMap entrySet() Method
Description
The Java WeakHashMap entrySet() method is used to return a collection view of the mappings contained in this map. Each element in the returned collection is a Map.Entry. The collection is backed by the map, so changes to the map are reflected in the collection and reverse.
Declaration
Following is the declaration for java.util.WeakHashMap.entrySet() method.
public Set<Map.Entry<K,V>> entrySet()
Parameters
NA
Return Value
The method call returns a collection view of the mappings contained in this map.
Exception
NA
Getting a Set View Key-Values in a WeakHashMap of Integer, Integer Pairs Example
The following example shows the usage of Java WeakHashMap entrySet() method to get a Set view of a Map. We've created a Map object of Integer,Integer pairs. Then few entries are added, map is printed. Using entrySet() method, set is retrieved and printed.
package com.tutorialspoint; import java.util.WeakHashMap; public class WeakHashMapDemo { public static void main(String args[]) { // create hash map WeakHashMap<Integer,Integer> newmap = new WeakHashMap<>(); // populate hash map newmap.put(1, 1); newmap.put(2, 2); newmap.put(3, 3); System.out.println("Initial map elements: " + newmap); System.out.println("EntrySet view: " + newmap.entrySet()); } }
Output
Let us compile and run the above program, this will produce the following result.
Initial map elements: {3=3, 2=2, 1=1} EntrySet view: [3=3, 2=2, 1=1]
Getting a Set View Key-Values in a WeakHashMap of Integer, String Pairs Example
The following example shows the usage of Java WeakHashMap entrySet() method to get a Set view of a Map. We've created a Map object of Integer,String pairs. Then few entries are added, map is printed. Using entrySet() method, set is retrieved and printed.
package com.tutorialspoint; import java.util.WeakHashMap; public class WeakHashMapDemo { public static void main(String args[]) { // create hash map WeakHashMap<Integer,String> newmap = new WeakHashMap<>(); // populate hash map newmap.put(1, "tutorials"); newmap.put(2, "point"); newmap.put(3, "is best"); System.out.println("Initial map elements: " + newmap); System.out.println("EntrySet view: " + newmap.entrySet()); } }
Output
Let us compile and run the above program, this will produce the following result.
Initial map elements: {3=is best, 2=point, 1=tutorials} EntrySet view: [3=is best, 2=point, 1=tutorials]
Getting a Set View Key-Values in a WeakHashMap of Integer, Object Pairs Example
The following example shows the usage of Java WeakHashMap entrySet() method to get a Set view of a Map. We've created a Map object of Integer,Student pairs. Then few entries are added, map is printed. Using entrySet() method, set is retrieved and printed.
package com.tutorialspoint; import java.util.WeakHashMap; public class WeakHashMapDemo { public static void main(String args[]) { // create hash map WeakHashMap<Integer,Student> newmap = new WeakHashMap<>(); // populate hash map newmap.put(1, new Student(1, "Julie")); newmap.put(2, new Student(2, "Robert")); newmap.put(3, new Student(3, "Adam")); System.out.println("Initial map elements: " + newmap); System.out.println("EntrySet view: " + newmap.entrySet()); } } 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 + " ]"; } }
Output
Let us compile and run the above program, this will produce the following result.
Initial map elements: {3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]} EntrySet view: [3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]]
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