Performance Increase

Many of us passes through the same situation of having a low performance of our application. But if you follow some of the tips and tricks below you will soon realize the increase in the performance.

Collections
Always assign size to ArrayLists and other collections. Ex:

Collection c = new ArrayList(10);

Strings
Always use

String abc = "I love Java";instead of
String abc = new String("I love Java");

JDBC
Always close these statements after use:

Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection("databaseUrl","username","password");
Statement stmt = conn.createStatement();
String strSql = "select * from abc";
ResultSet rs = stmt.executeQuery("strSql");// close these
stmt.close();
rs.close();
conn.close();
strSql=null;

Use only the required columns in select query:

Select FIRSTNAME,LASTNAME from PERSON;

instead of

Select * from Person;

JSP
Use session object as compared to hidden values, url rewriting and cookies

Use

System.out.print()

instead of

System.out.println();

wherever necessary