Serialize Hashset Java
The HashSet class implements the Set interface, backed by a hash table which is actually a HashMap instance. No guarantee is made as to the iteration order of the set which means that the class does not guarantee the constant order of elements over time. This class permits the null element. The class also offers constant time performance for the basic operations like add, remove, contains and size assuming the hash function disperses the elements properly among the buckets, which we shall see further in the article.Few important features of HashSet are:. Implements. Underlying data structure for HashSet is hashtable.
As it implements the Set Interface, duplicate values are not allowed. Objects that you insert in HashSet are not guaranteed to be inserted in same order.
Objects are inserted based on their hash code. NULL elements are allowed in HashSet. HashSet also implements Searlizable and Cloneable interfaces.Now for the maintenance of constant time performance, iterating over HashSet requires time proportional to the sum of the HashSet instance’s size (the number of elements) plus the “capacity” of the backing HashMap instance (the number of buckets).
Thus, it’s very important not to set the initial capacity too high (or the load factor too low) if iteration performance is important.Initial Capacity: The initial capacity means the number of buckets when hashtable (HashSet internally uses hashtable data structure) is created. The number of buckets will be automatically increased if the current size gets full.Load Factor: The load factor is a measure of how full the HashSet is allowed to get before its capacity is automatically increased.
Serialize Hashset Java Pdf
Java Serialization and DeserializationSerialization is a process of converting an object into a sequence of bytes which can be persisted to a disk or database or can be sent through streams. The reverse process of creating object from sequence of bytes is called deserialization.A class must implement Serializable interface present in java.io package in order to serialize its object successfully. Serializable is a marker interface that adds serializable behaviour to the class implementing it.Java provides Serializable API encapsulated under java.io package for serializing and deserializing objects which include,. java.io.serializable. java.io.Externalizable.
Serialize Hashset Java Tutorial
ObjectInputStream. and ObjectOutputStream etc.Java Marker interfaceMarker Interface is a special interface in Java without any field and method. Marker interface is used to inform compiler that the class implementing it has some special behaviour or meaning. Some example of Marker interface are,. java.io.serializable. java.lang.Cloneable.
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Hashmap
java.rmi.Remote. java.util.RandomAccessAll these interfaces does not have any method and field. They only add special behavior to the classes implementing them. However marker interfaces have been deprecated since Java 5, they were replaced by Annotations.
Annotations are used in place of Marker Interface that play the exact same role as marker interfaces did before.Signature of writeObject and readObjectwriteObject method of ObjectOutputStream class serializes an object and send it to the output stream. Public final void writeObject( object x) throws IOExceptionreadObject method of ObjectInputStream class references object out of stream and deserialize it. Public final Object readObject throws IOException,ClassNotFoundExceptionwhile serializing if you do not want any field to be part of object state then declare it either static or transient based on your need and it will not be included during java serialization process.
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