Class SimpleDB

java.lang.Object
SimpleDB
public class SimpleDB extends Object
SimpleDB is a basic key-value database using a HashMap for in-memory storage. It supports basic CRUD operations and can persist/load data to/from a file using serialization.

  • Constructor Summary

    Constructors
    Constructor
    Description
    SimpleDB()
    Constructs a new, empty SimpleDB.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Removes all key-value pairs from the database.
    boolean
    containsKey(String key)
    Checks if the database contains the given key.
    void
    delete(String key)
    Removes the key-value pair for the given key from the database.
    String
    get(String key)
    Retrieves the value associated with the given key.
    void
    load()
    Loads the database from a file using deserialization.
    void
    persist()
    Serializes and saves the database to a file.
    void
    put(String key, String value)
    Adds or updates a key-value pair in the database.
    int
    size()
    Returns the number of key-value pairs in the database.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • SimpleDB

      public SimpleDB()
      Constructs a new, empty SimpleDB.

  • Method Details

    • put

      public void put(String key, String value)
      Adds or updates a key-value pair in the database.
      Parameters:
      key - the key to add or update
      value - the value to associate with the key

    • get

      public String get(String key)
      Retrieves the value associated with the given key.
      Parameters:
      key - the key to look up
      Returns:
      the value associated with the key, or null if not found

    • delete

      public void delete(String key)
      Removes the key-value pair for the given key from the database.
      Parameters:
      key - the key to remove

    • containsKey

      public boolean containsKey(String key)
      Checks if the database contains the given key.
      Parameters:
      key - the key to check
      Returns:
      true if the key exists, false otherwise

    • size

      public int size()
      Returns the number of key-value pairs in the database.
      Returns:
      the size of the database

    • clear

      public void clear()
      Removes all key-value pairs from the database.

    • persist

      public void persist()
      Serializes and saves the database to a file.

    • load

      public void load()
      Loads the database from a file using deserialization. Suppresses unchecked cast warning.