In The Series of Java Programming Language, we are learning about HashSet and TreeSet. In this post, we are going to learn about LinkedHashSet, which also extends the HashSet Class and implements the Set Interface. LinkedHashSet stores the elements in the same order which they are inserted.
public class LinkedHashSet<E> extends HashSet<E> implements Set<E>, Cloneable, Serializable
{
//implementation
}LinkedHashSet Syntax
LinkedHashSet<String> hs = new LinkedHashSet<String>();
Important Points about LinkedHashSet
- It Extends HashSet class and implements Set Interface.
- Duplicate Values are not allowed inside LinkedHashSet Class.
- One Null Element is allowed inside LinkedHashSet.
- Elements are stored in an insertion order that means the elements get stored in the same order in which they have added into the LinkedHashSet.
- This class provides consistent performance for an operation like add, remove, contains and size.
- LinkedHashSet is not threaded safe or not synchronised, that means when multiple threads are acting on this, and then the result is un-deterministic. But externally we can make it synchronised with Collections.synchronizedSet(new LinkedHashSet()).
- LinkedHashSet implements Serializable and Cloneable interfaces.
LinkedHashSet Constructors
- LinkedHashSet(): This constructor is used to create a default HashSet.
- LinkedHashSet(Collection C): Used in initialising the HashSet with the elements of the collection C
- LinkedHashSet(int size): Used to initialise the size of the LinkedHashSet with the integer mentioned in the parameter.
- LinkedHashSet(int capacity, float fillRatio): Can be used to initialise both the capacity and the fill ratio, also called the load capacity of the LinkedHashSet with the arguments mentioned in the parameter. When the number of elements exceeds the capacity of the hash set is multiplied with the fill ratio thus expanding the capacity of the LinkedHashSet
LinkedHashSet Methods
- spliterator (): This method creates a late-binding and fail-fast Spliterator over the elements in this set.
- Clear (): This method removes all of the elements from this set.
- Contains (Object o): This method returns true if this set contains the specified element.
How to Find The LinkedHashSet Size & Check Empty In Java?
package com.java.Softwaretestingblog;
import java.util.LinkedHashSet;
public class LkdHashSetOperations {
public static void main(String[] args) {
// TODO Auto-generated method stub
LinkedHashSet<String> lhs = new LinkedHashSet<String>();
//add elements to HashSet
lhs.add("first");
lhs.add("second");
lhs.add("third");
System.out.println(lhs);
System.out.println("LinkedHashSet size: "+lhs.size());
System.out.println("Is LinkedHashSet emplty? : "+lhs.isEmpty());
}
}Check Also: Compare two String matches()
Output:
[first, second, third] LinkedHashSet size: 3 Is LinkedHashSet emplty? : false
How to Remove LinkedHashSet Elements in Java With Example?
package com.java.Softwaretestingblog;
import java.util.LinkedHashSet;
public class LinkedHashSetClear {
public static void main(String[] args) {
// TODO Auto-generated method stub
LinkedHashSet<String> lhs = new LinkedHashSet<String>();
//add elements to HashSet
lhs.add("first");
lhs.add("second");
lhs.add("third");
System.out.println("My LinkedHashSet content:");
System.out.println(lhs);
System.out.println("Clearing LinkedHashSet:");
lhs.clear();
System.out.println("Content After clear:");
System.out.println(lhs);
}
}Check Also: Search LinkedHashSet Value
Output:
[first, second, third] Does set contains 'first'? true
Ref: article
How to Print Iterate LinkedHashSet Elements In Java With Example?
Check Also: Find TreeMap Value
package com.java.Softwaretestingblog;
import java.util.Iterator;
import java.util.LinkedHashSet;
public class LinkedHashSetIteratorExample {
public static void main(String[] args) {
// TODO Auto-generated method stub
LinkedHashSet<String> lhs = new LinkedHashSet<String>();
//add elements to HashSet
lhs.add("first");
lhs.add("second");
lhs.add("third");
Iterator itr = lhs.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
}
}Read Also: Remove LinkedHashSet Elements
Output:
first second third
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