Java Hashtable clone() Method

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Description

The Java Hashtable clone() method is used to create a shallow copy of this hashtable.

Declaration

Following is the declaration for java.util.Hashtable.clone() method.

 public Object clone() 

Parameters

NA

Return Value

The method call returns a clone of the hashtable.

Exception

NA

Cloning a HashTable of Integer, Integer Pair Example

The following example shows the usage of Java Hashtable clone() method to get a shallow copy of a Hashtable. We've created two Hashtable objects of Integer,Integer pairs. Then few entries are added to one table, another table is populated using clone() method and then both hashtables are printed.

 package com.tutorialspoint; import java.util.Hashtable; public class HashtableDemo { public static void main(String args[]) { // create two hash hashtables Hashtable<Integer, Integer> hashtable1 = new Hashtable<>(); Hashtable<Integer, Integer> hashtable2 = new Hashtable<>(); // populate 1st table hashtable1.put(1, 1); hashtable1.put(2, 2); hashtable1.put(3, 3); // clone 1st table hashtable2 = (Hashtable)hashtable1.clone(); System.out.println("1st Hashtable: " + hashtable1); System.out.println("Cloned 2nd Hashtable: " + hashtable2); } } 

Output

Let us compile and run the above program, this will produce the following result.

 1st Hashtable: {3=3, 2=2, 1=1} Cloned 2nd Hashtable: {3=3, 2=2, 1=1} 

Cloning a HashTable of Integer, String Pair Example

The following example shows the usage of Java Hashtable clone() method to get a shallow copy of a Hashtable. We've created two Hashtable objects of Integer,String pairs. Then few entries are added to one table, another table is populated using clone() method and then both hashtables are printed.

 package com.tutorialspoint; import java.util.Hashtable; public class HashtableDemo { public static void main(String args[]) { // create two hash hashtables Hashtable<Integer, String> hashtable1 = new Hashtable<>(); Hashtable<Integer, String> hashtable2 = new Hashtable<>(); // populate 1st table hashtable1.put(1, "A"); hashtable1.put(2, "B"); hashtable1.put(3, "C"); // clone 1st table hashtable2 = (Hashtable)hashtable1.clone(); System.out.println("1st Hashtable: " + hashtable1); System.out.println("Cloned 2nd Hashtable: " + hashtable2); } } 

Output

Let us compile and run the above program, this will produce the following result.

 1st Hashtable: {3=C, 2=B, 1=A} Cloned 2nd Hashtable: {3=C, 2=B, 1=A} 

Cloning a HashTable of Integer, Object Pair Example

The following example shows the usage of Java Hashtable clone() method to get a shallow copy of a Hashtable. We've created two Hashtable objects of Integer,Student pairs. Then few entries are added to one table, another table is populated using clone() method and then both hashtables are printed.

 package com.tutorialspoint; import java.util.Hashtable; public class HashtableDemo { public static void main(String args[]) { // create two hash hashtables Hashtable<Integer, Student> hashtable1 = new Hashtable<>(); Hashtable<Integer, Student> hashtable2 = new Hashtable<>(); // populate hash table hashtable1.put(1, new Student(1, "Julie")); hashtable1.put(2, new Student(2, "Robert")); hashtable1.put(3, new Student(3, "Adam")); // clone 1st table hashtable2 = (Hashtable)hashtable1.clone(); System.out.println("1st Hashtable: " + hashtable1); System.out.println("Cloned 2nd Hashtable: " + hashtable2); } } 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.

 1st Hashtable: {3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]} Cloned 2nd Hashtable: {3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]}