Importing Packages in Java

Java Packages

• The java.lang package provides fundamental classes and interfaces automatically imported into every Java program.
• The java.util package contains the collection framework and utility classes like ArrayList and HashMap.
• The java.io package provides classes for input and output operations like FileInputStream and FileOutputStream.
• The javax.swing package contains classes and interfaces for creating graphical user interfaces (GUI).

Java Virtual Machine (JVM)

• The main function of JVM is to execute Java bytecode.

Importing Packages

• The java.io package is primarily used for reading and writing data from files and streams.
• The purpose of importing a package in Java is to use the classes and interfaces provided by the package.
• To import all classes from a package, use the import statement with the * wildcard, e.g. import java.util.*;.
• A static import allows you to import static members of a class.

Java Applets

• The code attribute is required in the `` tag in HTML to embed Java applets into web pages.

StringUtils Class

• The isEmpty method in the StringUtils class checks if a string is empty.
• To access the isEmpty method of the StringUtils class, use the StringUtils.isEmpty() method after importing the class.

Java Features

• Java's Just-In-Time (JIT) compilation feature improves execution speed by translating bytecode into native machine code at runtime.
• Java's socket programming feature allows communication between programs running on different machines over a network.
• Java's dynamic loading feature supports the loading of components on demand.
• Java's modular architecture makes it easy to extend functionality and integrate with other technologies.

Java Standard Library

• The Java standard library (Java API) provides ready-to-use classes and methods for various tasks.

Java Community

• The vast and active developer community helps Java developers by providing resources, documentation, and support.

Exception Handling

• An exception in Java disrupts the normal flow of program execution.
• When an exceptional condition arises, an exception object is created by a method.
• An exception object in Java contains information about the error, such as the type of exception and the location of the error.
• The try-catch-finally block provides a robust exception handling mechanism in Java.

StringBuffer Class

• When the append method is called on a StringBuffer object, it adds the specified string to the end of the buffer.
• The reverse method, when called on a StringBuffer containing 'Hello World', returns 'dlroW olleH'.

Data Type Conversion

• The term used for explicitly converting a value of a larger data type to a smaller data type is called narrowing.
• Narrowing conversions may result in loss of data or precision.
• In Java, narrowing conversions are typically performed using explicit casts.
• Examples of narrowing conversions include long to int, double to float, and int to byte.