How to wrapping your own packages in java, JAVA Programming

How to Wrapping Your Own Packages in java?

Java does not limit you to using just the system supplied packages. You can write your own as well. You write packages just such as you write any other Java program. Make sure you follow these rules:

1. There must be no more than one public class per file.
2. All files within the package must be named classname.java where classname is the name of the single public class in the file.
3. At the extremely top of each file in the package, before any import statements, put the statement
package myPackage;

To use the package in other programs, compile the .java files as commonly and then move the resulting .class files within the appropriate subdirectory of one of the directories referenced in your CLASSPATH environment variable. For example if /home/elharo/classes is in your CLASSPATH and your package is known as package1, then you would form a directory known as package1 in /home/elharo/classes and then put all the .class files in the package in /home/elharo/classes/package1.

For example,
package com.macfaq.net;

import java.net.*;

public class URLSplitter {

public static void main(String[] args) {

for (int i = 0; i < args.length; i++) {
try {
URL u = new URL(args[i]);
System.out.println("Protocol: " + u.getProtocol());
System.out.println("Host: " + u.getHost());
System.out.println("Port: " + u.getPort());
System.out.println("File: " + u.getFile());
System.out.println("Ref: " + u.getRef());
}
catch (MalformedURLException e) {
System.err.println(args[i] + " is not a valid URL");
}
}

}

}

$ javac -d /home/elharo/classes URLSplitter.java
The -d flag to the compiler tells it to form the essential directories such as elharo/net in the specified directory. In this instance, URLSplitter.class is placed in /home/elharo/classes/com/macfaq/net. You can use the usual shell syntax such as. For the current directory or ~ for your home directory.

Posted Date: 5/16/2013 2:25:50 AM | Location : United States







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