Technical Interview Questions
JDBC is a set of Java API for executing SQL statements. This API consists of a set of classes and interfaces to enable programs to write pure Java Database applications. JDBC technology drivers fit into one of four categories: A JDBC-ODBC bridgeprovides JDBC API access via one or more ODBC drivers. Note that some ODBC native … Read more
Here is an example of a JavaTechnology custom object that implements a default sorting logic based on the rank (i.e popularity). public class JavaTechnology implements Comparable<JavaTechnology>{ private String name; private int rank; // popularity lower value means more popular public JavaTechnology(String name, int rank){ this.name = name; this.rank = rank; } //default … Read more
Yes, 2 things — firstly, the above sort is case sensitive, that is the uppercase takes priority over lowercase pushing ‘Java’ after ‘JSP’. Secondly, if the collection had any null values, it will throw a NullpointerException. These two issues can be rectified by providing a custom sorting implementation that ignores case and handles null values … Read more
Here is the sample code that makes use of the default compareTo( ) provided in the String class as it implements the Comparable interface and the Collections utility class that provides a sorting method, which internally uses the efficient “merge sort” algorithm. import java.util.Arrays; import java.util.Collections; import java.util.List; public class Sort1 { public static … Read more
cmd/designated folder/ jar cf name.jar *.* Create a file: META-INF/MANIFEST.MF Add a line: Main-Class: com.myco.calc.CalculatorDemo Include META-INF/MANIFEST.MF in calculator.jar Run with java -jar calculator.jar This is useful in domain or value object class to compare different object fields in an equals method public class DomainObject { //protected because only inheriting domain classes can use … Read more