Package org.sqlite

Class Function

java.lang.Object
org.sqlite.Function
Direct Known Subclasses:
Function.Aggregate
public abstract class Function extends Object
Provides an interface for creating SQLite user-defined functions.

A subclass of org.sqlite.Function can be registered with Function.create() and called by the name it was given. All functions must implement xFunc(), which is called when SQLite runs the custom function. E.g. 

      Class.forName("org.sqlite.JDBC");
      Connection conn = DriverManager.getConnection("jdbc:sqlite:");

      Function.create(conn, "myFunc", new Function() {
          protected void xFunc() {
              System.out.println("myFunc called!");
          }
      });

      conn.createStatement().execute("select myFunc();");

Arguments passed to a custom function can be accessed using the protected functions provided. args() returns the number of arguments passed, while value_<type>(int) returns the value of the specific argument. Similarly, a function can return a value using the result(<type>) function.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    Function.Aggregate
    Provides an interface for creating SQLite user-defined aggregate functions.
    static class 
    Function.Window
    Provides an interface for creating SQLite user-defined window functions.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    FLAG_DETERMINISTIC
    Flag to provide to create(Connection, String, Function, int) that marks this Function as deterministic, making is usable in Indexes on Expressions.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Function()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    protected final int
    args()
    Returns the number of arguments passed to the function.
    static void
    create(Connection conn, String name, Function f)
    Registers a given function with the connection.
    static void
    create(Connection conn, String name, Function f, int flags)
    Registers a given function with the connection.
    static void
    create(Connection conn, String name, Function f, int nArgs, int flags)
    Registers a given function with the connection.
    static void
    destroy(Connection conn, String name)
    Removes a named function from the given connection.
    static void
    destroy(Connection conn, String name, int nArgs)
    Removes a named function from the given connection.
    protected final void
    error(String err)
    Called by xFunc to throw an error.
    protected final void
    result()
    Called by xFunc to return a value.
    protected final void
    result(byte[] value)
    Called by xFunc to return a value.
    protected final void
    result(double value)
    Called by xFunc to return a value.
    protected final void
    result(int value)
    Called by xFunc to return a value.
    protected final void
    result(long value)
    Called by xFunc to return a value.
    protected final void
    result(String value)
    Called by xFunc to return a value.
    protected final byte[]
    value_blob(int arg)
    Called by xFunc to access the value of an argument.
    protected final double
    value_double(int arg)
    Called by xFunc to access the value of an argument.
    protected final int
    value_int(int arg)
    Called by xFunc to access the value of an argument.
    protected final long
    value_long(int arg)
    Called by xFunc to access the value of an argument.
    protected final String
    value_text(int arg)
    Called by xFunc to access the value of an argument.
    protected final int
    value_type(int arg)
    Called by xFunc to access the value of an argument.
    protected abstract void
    xFunc()
    Called by SQLite as a custom function.

    Methods inherited from class java.lang.Object

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

  • Field Details

  • Constructor Details

    • Function

      public Function()

  • Method Details

    • create

      public static void create(Connection conn, String name, Function f) throws SQLException
      Registers a given function with the connection.
      Parameters:
      conn - The connection.
      name - The name of the function.
      f - The function to register.
      Throws:
      SQLException

    • create

      public static void create(Connection conn, String name, Function f, int flags) throws SQLException
      Registers a given function with the connection.
      Parameters:
      conn - The connection.
      name - The name of the function.
      f - The function to register.
      flags - Extra flags to pass, such as FLAG_DETERMINISTIC
      Throws:
      SQLException

    • create

      public static void create(Connection conn, String name, Function f, int nArgs, int flags) throws SQLException
      Registers a given function with the connection.
      Parameters:
      conn - The connection.
      name - The name of the function.
      f - The function to register.
      nArgs - The number of arguments that the function takes.
      flags - Extra flags to pass, such as FLAG_DETERMINISTIC
      Throws:
      SQLException

    • destroy

      public static void destroy(Connection conn, String name, int nArgs) throws SQLException
      Removes a named function from the given connection.
      Parameters:
      conn - The connection to remove the function from.
      name - The name of the function.
      nArgs - Ignored.
      Throws:
      SQLException

    • destroy

      public static void destroy(Connection conn, String name) throws SQLException
      Removes a named function from the given connection.
      Parameters:
      conn - The connection to remove the function from.
      name - The name of the function.
      Throws:
      SQLException

    • xFunc

      protected abstract void xFunc() throws SQLException
      Called by SQLite as a custom function. Should access arguments through value_*(int), return results with result(*) and throw errors with error(String).
      Throws:
      SQLException

    • args

      protected final int args() throws SQLException
      Returns the number of arguments passed to the function. Can only be called from xFunc().
      Throws:
      SQLException

    • result

      protected final void result(byte[] value) throws SQLException
      Called by xFunc to return a value.
      Parameters:
      value -
      Throws:
      SQLException

    • result

      protected final void result(double value) throws SQLException
      Called by xFunc to return a value.
      Parameters:
      value -
      Throws:
      SQLException

    • result

      protected final void result(int value) throws SQLException
      Called by xFunc to return a value.
      Parameters:
      value -
      Throws:
      SQLException

    • result

      protected final void result(long value) throws SQLException
      Called by xFunc to return a value.
      Parameters:
      value -
      Throws:
      SQLException

    • result

      protected final void result() throws SQLException
      Called by xFunc to return a value.
      Throws:
      SQLException

    • result

      protected final void result(String value) throws SQLException
      Called by xFunc to return a value.
      Parameters:
      value -
      Throws:
      SQLException

    • error

      protected final void error(String err) throws SQLException
      Called by xFunc to throw an error.
      Parameters:
      err -
      Throws:
      SQLException

    • value_text

      protected final String value_text(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException

    • value_blob

      protected final byte[] value_blob(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException

    • value_double

      protected final double value_double(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException

    • value_int

      protected final int value_int(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException

    • value_long

      protected final long value_long(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException

    • value_type

      protected final int value_type(int arg) throws SQLException
      Called by xFunc to access the value of an argument.
      Parameters:
      arg -
      Throws:
      SQLException