JAVA QUESTIONS

What is the difference between java.util.Iterator and java.util.ListIterator?

Iterator : Enables you to traverse through a collection in the forward direction only, for obtaining or removing elements

ListIterator : extends Iterator, and allows bidirectional traversal of list and also allows the modification of elements.

What is Metadata and why should I use it?

JDBC API has 2 Metadata interfaces

·        DatabaseMetaData

·        ResultSetMetaData.

 The DatabaseMetaData provides Comprehensive information about the database as a whole. This interface is implemented by driver vendors to let users know the capabilities of a Database Management System (DBMS) in combination with the driver based on JDBC technology ("JDBC driver") that is used with it. Below is a sample code which demonstrates how we can use the DatabaseMetaData

DatabaseMetaData md = conn.getMetaData();

 System.out.println("Database Name: " + md.getDatabaseProductName());

 System.out.println("Database Version: " + md.getDatabaseProductVersion());

 System.out.println("Driver Name: " + md.getDriverName());

 System.out.println("Driver Version: " + md.getDriverVersion());

The ResultSetMetaData is an object that can be used to get information about the types and properties of the columns in a ResultSet object. Use DatabaseMetaData to find information about your database, such as its capabilities and structure. Use ResultSetMetaData to find information about the results of an SQL query, such as size and types of columns. Below a sample code which demonstrates how we can use the ResultSetMetaData

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");

     ResultSetMetaData rsmd = rs.getMetaData();

     int numberOfColumns = rsmd.getColumnCount();

     boolean b = rsmd.isSearchable(1);

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