Download Java SE Tutorial offline version

The Java Tutorials are practical guides for programmers who want to use the Java programming language to create applications. They include hundreds of complete, working examples, and dozens of lessons. Groups of related lessons are organized into "trails".

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Learning Network Programming with Java

Learning Network Programming with Java
Key Features

• Learn to deliver superior server-to-server communication through the networking channels
• Gain expertise of the networking features of your own applications to support various network architectures such as client/server and peer-to-peer
• Explore the issues that impact scalability, affect security, and allow applications to work in a heterogeneous environment

Book Description
Network-aware applications are becoming more prevalent and play an ever-increasing role in the world today. Connecting and using an Internet-based service is a frequent requirement for many applications. Java provides numerous classes that have evolved over the years to meet evolving network needs. These range from low-level socket and IP-based approaches to those encapsulated in software services.

This book explores how Java supports networks, starting with the basics and then advancing to more complex topics. An overview of each relevant network technology is presented followed by detailed examples of how to use Java to support these technologies.

We start with the basics of networking and then explore how Java supports the development of client/server and peer-to-peer applications. The NIO packages are examined as well as multitasking and how network applications can address practical issues such as security.

A discussion on networking concepts will put many network issues into perspective and let you focus on the appropriate technology for the problem at hand. The examples used will provide a good starting point to develop similar capabilities for many of your network needs.

What you will learn

• Connect to other applications using sockets
• Use channels and buffers to enhance communication between applications
• Access network services and develop client/server applications
• Explore the critical elements of peer-to-peer applications and current technologies available
• Use UDP to perform multicasting
• Address scalability through the use of core and advanced threading techniques
• Incorporate techniques into an application to make it more secure
• Configure and address interoperability issues to enable your applications to work in a heterogeneous environment

About the Author
Richard M Reese has worked in both industry and academia. For 17 years, he worked in the telephone and aerospace industries, serving in several capacities, including research and development, software development, supervision, and training. He currently teaches at Tarleton State University, where he has the opportunity to apply his years of industry experience to enhance his teaching.

Richard has written several Java books and a C Pointer book. He uses a concise and easy-to-follow approach to topics at hand. His Java books have addressed EJB 3.1, updates to Java 7 and 8, certification, functional programming, jMonkeyEngine, and natural language processing.

Table of Contents

1. Getting Started with Network Programming
2. Network Addressing
3. NIO Support for Networking
4. Client/Server Development
5. Peer-to-Peer Networks
6. UDP and Multicasting
7. Network Scalability
8. Network Security
9. Network Interoperability

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Get ISO country code for the given latitude longitude using GeoNames Java Client

Last example show "Get ISO country code for the given latitude/longitude, using GeoNames Web Service, using HttpURLConnection". GeoNames provide Java Client for GeoNames Webservices to help developers to easily access the geonames web services with java. This post show how to use it in Android.

To use Java Client for GeoNames Webservices in you Android Studio project, you have to download both geonames-1.1.13.jar and jdom-1.0.jar to your local machine. Visit http://www.geonames.org/source-code/ to download.

Then you have to add the JAR modules in your Android Studio Project, refer to the video.


dependencies of :geonames-1.1.13 and :jdom-1.0 will be added in your build.gradle.

Example to get ISO country code for the given latitude/longitude, using GeoNames Java Client:


MainActivity.java

package com.blogspot.android_er.androidgeonames;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.geonames.GeoNamesException;
import org.geonames.WebService;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

 EditText latText;
 EditText lonText;
 Button btnFind;
 TextView textResult;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 latText = (EditText)findViewById(R.id.latText);
 lonText = (EditText)findViewById(R.id.lonText);
 btnFind = (Button)findViewById(R.id.find);
 textResult = (TextView)findViewById(R.id.result);

 btnFind.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 String strLat = latText.getText().toString();
 String strLon = lonText.getText().toString();

 boolean parsable = true;
 Double lat = null, lon = null;

 try{
 lat = Double.parseDouble(strLat);
 }catch (NumberFormatException ex){
 parsable = false;
 Toast.makeText(MainActivity.this,
 "Latitude does not contain a parsable double",
 Toast.LENGTH_LONG).show();
 }

 try{
 lon = Double.parseDouble(strLon);
 }catch (NumberFormatException ex){
 parsable = false;
 Toast.makeText(MainActivity.this,
 "Longitude does not contain a parsable double",
 Toast.LENGTH_LONG).show();
 }

 if(parsable){
 new GeoNamesTask(textResult).execute(lat, lon);
 }

 }
 });
 }

 private class GeoNamesTask extends AsyncTask<Double, Void, String> {
 TextView tResult;

 public GeoNamesTask(TextView vResult){
 tResult = vResult;
 tResult.setText("");
 }

 @Override
 protected String doInBackground(Double... params) {
 return queryGeoNames_countryCode(params[0], params[1]);
 }

 @Override
 protected void onPostExecute(String s) {
 tResult.setText(s);
 }

 private String queryGeoNames_countryCode(double latitude, double longitude){
 String queryResult = "";

 /*
 Do not use the demo account for your app or your tests.
 It is only meant for the sample links on the documentation pages.
 Create your own account instead.
 */
 WebService.setUserName("demo");

 try {
 queryResult = "CountryCode: " + WebService.countryCode(latitude, longitude);
 } catch (IOException e) {
 e.printStackTrace();
 queryResult = e.getMessage();
 } catch (GeoNamesException e) {
 e.printStackTrace();
 queryResult = e.getMessage();
 }

 return queryResult;
 }
 }
}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 
 
 android_layout_width="match_parent"
 android_layout_height="match_parent"
 android_padding="16dp"
 android_orientation="vertical"
 tools_context=".MainActivity">

 <TextView
 android_layout_width="wrap_content"
 android_layout_height="wrap_content"
 android_layout_gravity="center_horizontal"
 android_autoLink="web"
 android_text="http://android-er.blogspot.com/"
 android_textStyle="bold" />

 <EditText
 android_id="@+id/latText"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"
 android_inputType="numberSigned|numberDecimal"
 android_hint="Latitude"
 android_text="47.03"/>

 <EditText
 android_id="@+id/lonText"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"
 android_inputType="numberSigned|numberDecimal"
 android_hint="Longitude"
 android_text="10.2"/>

 <Button
 android_id="@+id/find"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"
 android_text="find"/>

 <TextView
 android_id="@+id/result"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"
 android_textSize="28dp"
 android_textStyle="bold"/>
</LinearLayout>

Permission of "android.permission.INTERNET" is needed in AndroidManifest.xml

 <uses-permission android_name="android.permission.INTERNET"/>

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Java code to listing Network Interface Addresses run on Windows 10

One of the most useful pieces of information you can get from a network interface is the list of IP addresses that are assigned to it. You can obtain this information from a NetworkInterface instance by using one of two methods. The first method, getInetAddresses(), returns an Enumeration of InetAddress. The other method, getInterfaceAddresses(), returns a list of java.net.InterfaceAddress instances. This method is used when you need more information about an interface address beyond its IP address. For example, you might need additional information about the subnet mask and broadcast address when the address is an IPv4 address, and a network prefix length in the case of an IPv6 address. ~ https://docs.oracle.com/javase/tutorial/networking/nifs/listing.html

The following example program lists all the network interfaces and their addresses on a machine (tested on PC running Windows 10):

package javalistinetaddress;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Collections;
import java.util.Enumeration;

public class JavaListInetAddress {

 public static void main(String[] args) throws SocketException {
 Enumeration<NetworkInterface> nets = NetworkInterface.getNetworkInterfaces();
 for (NetworkInterface netint : Collections.list(nets))
 displayInterfaceInformation(netint);
 }
 
 static void displayInterfaceInformation(NetworkInterface netint) throws SocketException {
 System.out.printf("Display name: %s ", netint.getDisplayName());
 System.out.printf("Name: %s ", netint.getName());
 Enumeration<InetAddress> inetAddresses = netint.getInetAddresses();
 for (InetAddress inetAddress : Collections.list(inetAddresses)) {
 System.out.printf("InetAddress: %s ", inetAddress);
 }
 System.out.printf(" ");
 }
 
}

Related:
- Java code to listing Network Interface Addresses, run on Raspberry Pi/Raspbian Jessie

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Download and Install JDK8 on Ubuntu 15 10 using update alternatives and also set JAVA HOME

This post show how to Install JDK8 on Ubuntu 15.10 (running in VirtualBox hosted on Windows 10).

To download Oracle JDK:
- visit Java SE Downloads page.
- Click to download Java Platform (JDK).
- Accept agreement and sselect download file, jdk-8u65-linux-x64.tar.gz.

Download and unpack in your local storage. /home/eric/jdk1.8.0_65 folder for me.

Setup java and javac update-alternatives:
Run the command:
$ sudo update-alternatives --install /usr/bin/javac javac /home/eric/jdk1.8.0_65/bin/javac 1
$ sudo update-alternatives --install /usr/bin/java java /home/eric/jdk1.8.0_65/bin/java 1

$ sudo update-alternatives --config javac
$ sudo update-alternatives --config java

Where /home/eric/jdk1.8.0_65 is the folder of jdk.

Check the video.

---

Set JAVA_HOME also:

Setup JAVA_HOME and path to JDK on Linux (Ubuntu in this example), edit the file .bashrc
$ nano .bashrc

Add the line:
export JAVA_HOME=<path to jdk>
export PATH=$JAVA_HOME/bin:$PATH

Where <path to jdk> is the path to the installed JDK.

---

Alternatively, you can install also Install Oracle java8 on Ubuntu 15.10 via PPA.

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Limit EditText to accept signed decimal numbers only in xml and java

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 
 
 android_layout_width="match_parent"
 android_layout_height="match_parent"
 android_padding="16dp"
 android_orientation="vertical"
 tools_context=".MainActivity">

 <TextView
 android_layout_width="wrap_content"
 android_layout_height="wrap_content"
 android_layout_gravity="center_horizontal"
 android_autoLink="web"
 android_text="http://android-er.blogspot.com/"
 android_textStyle="bold" />

 <EditText
 android_id="@+id/edittext1"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"
 android_inputType="numberSigned|numberDecimal"/>
 <EditText
 android_id="@+id/edittext2"
 android_layout_width="match_parent"
 android_layout_height="wrap_content"/>

</LinearLayout>

MainActivity.java

package com.blogspot.android_er.androiddecimalnumberedittext;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.InputType;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 EditText editText1 = (EditText)findViewById(R.id.edittext1);
 EditText editText2 = (EditText)findViewById(R.id.edittext2);
 editText2.setInputType(InputType.TYPE_CLASS_NUMBER
 | InputType.TYPE_NUMBER_FLAG_DECIMAL
 | InputType.TYPE_NUMBER_FLAG_SIGNED);
 }
}

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