java notes

  Java Package A java package is a group of similar types of classes, interfaces and sub-packages. Package in java can be categorized in two form, built-in package and user-defined package. There are many built-in packages such as java, lang, awt, javax, swing, net, io, util, sql etc.  Advantage of Java Package Java package is used to categorize the classes and interfaces so that they can be easily maintained. 2) Java package provides access protection. 3) Java package removes naming collision.  s imple example of java package package mypack;   public class Simple{     public static void main(String args[]) {       System.out.println("Welcome to package");      }   } How to access package from another package? There are three ways to access the package from outside the package. import package.*; import package.classname; fully qualified name.      1) Using p...

  Java StringBuffer class StringBuffer is a peer class of String that provides much of the functionality of strings. String represents fixed-length, immutable character sequences while StringBuffer represents growable and writable character sequences. Syntax: StringBuffer s = new StringBuffer(“text"); Important Constructors of StringBuffer class:- Constructor Description StringBuffer() creates an empty string buffer with the initial capacity of 16. StringBuffer(String str) creates a string buffer with the specified string. StringBuffer(int capacity) creates an empty string buffer with the specified capacity as length.   Important methods of StringBuffer class Modifier and Type Method Description public synchronized StringBuffer append(String s) ...