- Java.util Package Classes
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- 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
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- 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
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- Java.util - Discussion
Java IdentityHashMap put() Method
Description
The Java IdentityHashMap put(K key, V value) method is used to associate the specified value with the specified key in this identity hash map. If the map previously contained a mapping for this key, the old value is replaced.
Declaration
Following is the declaration for java.util.IdentityHashMap.put() method.
public V put(K key, V value)
Parameters
key − This is the key with which the specified value is to be associated.
value − This is the value to be associated with the specified key.
Return Value
The method call returns the previous value associated with key, or null if there was no mapping for key.
Exception
NA
Adding an Entry to an IdentityHashMap of Integer, Integer Pair Example
The following example shows the usage of Java IdentityHashMap put() method to put few values in a Map. We've created a Map object of Integer,Integer pairs. Then few entries are added using put() method and then map is printed.
package com.tutorialspoint; import java.util.IdentityHashMap; public class IdentityHashMapDemo { public static void main(String args[]) { // create identity map IdentityHashMap<Integer,Integer> newmap = new IdentityHashMap<>(); // populate identity map newmap.put(1, 1); newmap.put(2, 2); newmap.put(3, 3); System.out.println("Map elements: " + newmap); } }
Output
Let us compile and run the above program, this will produce the following result.
Map elements: {2=2, 3=3, 1=1}
Adding an Entry to an IdentityHashMap of Integer, String Pair Example
The following example shows the usage of Java IdentityHashMap put() method to put few values in a Map. We've created a Map object of Integer,String. Then few entries are added using put() method and then map is printed.
package com.tutorialspoint; import java.util.IdentityHashMap; public class IdentityHashMapDemo { public static void main(String args[]) { // create identity map IdentityHashMap<Integer,String> newmap = new IdentityHashMap<>(); // populate identity map newmap.put(1, "tutorials"); newmap.put(2, "point"); newmap.put(3, "is best"); System.out.println("Map elements: " + newmap); } }
Output
Let us compile and run the above program, this will produce the following result.
Map elements: {2=point, 3=is best, 1=tutorials}
Adding an Entry to an IdentityHashMap of Integer, Object Pair Example
The following example shows the usage of Java IdentityHashMap put() method to put few values in a Map. We've created a Map object of Integer,Student pairs. Then few entries are added using put() method and then map is printed.
package com.tutorialspoint; import java.util.IdentityHashMap; public class IdentityHashMapDemo { public static void main(String args[]) { // create identity map IdentityHashMap<Integer,Student> newmap = new IdentityHashMap<>(); // populate identity 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("Map elements: " + newmap); } } 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.
Map elements: {1=[ 1, Julie ], 3=[ 3, Adam ], 2=[ 2, Robert ]}
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