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Getting enviroment information on Android

Mar 16th

This is a simple program I wrote called Who Am I that shows informations about the device which it is running. Which can be useful for developers and maybe advanced users.

Download:

WhoAmI.tar.bz2 – Eclipse project. It’s configured for Android platform 4 (1.6) but should work without problems in newer Android platform versions.
WhoAmI.apk – Application installation Android package.

Main Activity source code:

package net.silveiraneto.whoami;
 
import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.widget.EditText;
 
public class WhoAmI extends Activity {
    private EditText mEditor;
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
 
        setContentView(R.layout.whoami);
 
        mEditor = (EditText) findViewById(R.id.editor);
 
        Object[][] properties = {
        	{"Build.BOARD", Build.BOARD},
        	{"Build.BRAND", Build.BRAND},
        	{"Build.CPU_ABI", Build.CPU_ABI},
        	{"Build.DEVICE", Build.DEVICE},
        	{"Build.DISPLAY", Build.DISPLAY},
        	{"Build.FINGERPRINT", Build.FINGERPRINT},
        	{"Build.HOST", Build.HOST},
        	{"Build.ID", Build.ID},
        	{"Build.MANUFACTURER", Build.MANUFACTURER},
        	{"Build.MODEL", Build.MODEL},
        	{"Build.PRODUCT", Build.PRODUCT},
        	{"Build.TAGS", Build.TAGS},
        	{"Build.TIME", Build.TIME},
        	{"Build.USER", Build.USER},
        };
 
        for(Object[] prop: properties) {
        	mEditor.append(String.format("%s: %s\n", prop[0], prop[1]));
        }
    }
}

And its Android Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="net.silveiraneto.whoami">
    <application android:label="Who Am I">
        <activity android:name="WhoAmI">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

Android, Eclipse, Java, programming, who am i, whoami

Capturas de Tela no Android

Mar 4th

Posted by Silveira in english

No comments

Quando desenvolvendo aplicações móveis para o Android as vezes precisamos obter imagens do dispositivo para comparar com um alguma referencia no computador. Como tirar screenshots no Android? Usar uma aplicação para isso e então passar as imagens para o computador? Não, há um jeito mais fácil.

Juntamente com o Android SDK há uma ferramenta na pasta tools chamada ddms (Dalvik Debug Monitor Server). O ddms ainda está pouco integrado com o plugin ADT do Eclipse e também pouco documentado, mas é extremamente útil para várias tarefas como monitoras o heap de memória, threads, processos e, é claro, tirar screenshots.

Para utiliza-lo com todas suas funcionalidades lembre-se de desligar primeiro o Eclipse (porque no momento só pode ter um aplicativo conectado ao ADB), porém que para fins de captura de tela isso não é necessário. Selecione um dispositivo, vá no menu Devices → Screen Capture (Control-S). Pronto, você tem no computador uma captura da tela do dispositivo.

Android, Dalvik, Dalvik Debug Monitor Server, ddms, development, mobile

The Caps Lock Java Socket Server

Feb 27th

Posted by Silveira in english

No comments

Here is a simple server for those who are starting studying sockets or just needs a simple socket server example for reuse while writing your own behavior.

Features:

A client should enter a string and the server would answer the same string, with each symbol in up case, when possible.
Default port at 8080.
One client at time.
No multi threading. I said its a simple server.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
 
public class Server {
	private static final int DEFAULT = 8080;
 
	public Server() {
		this(DEFAULT);
	}
 
	public Server(int port) {
		ServerSocket sock;
 
		try {
			sock = new ServerSocket(port);
			System.out.println(String.format("Listening on port %d.", port));
 
			while (true) {
				try {
					Socket client = sock.accept();
					System.out.println("A new connection was accepted.");
 
					BufferedReader in = new BufferedReader(
							new InputStreamReader(client.getInputStream()));
					OutputStreamWriter out = new OutputStreamWriter(client
							.getOutputStream());
					String input = "";
 
					while (!input.equals("exit")) {
						input = in.readLine();
						if (input.equals("shutdown")) {
							System.exit(0);
						}
						out.write(input.toUpperCase() + "\r\n");
						out.flush();
					}
 
					in.close();
					out.close();
					client.close();
					System.out.println("Connection closed.");
				} catch (NullPointerException npe) {
					System.out.println("Connection closed by client.");
				}
			}
		} catch (IOException ioe) {
			System.err.println(ioe);
			System.exit(-1);
		}
	}
 
	public static void main(String[] args) throws IOException {
		new Server();
	}
}

Usage:

$ javac Server.java
$ java Server
Listening on port 8080.

In another terminal:

$ telnet localhost 8080
Trying ::1…
Connected to localhost.
Escape character is ‘^]’.
hi
HI
The quick brown fox jumps over the lazy dog.
THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.
exi
EXI
exit
EXIT
Connection closed by foreign host.

caps lock, Java, programming, socket, upcase

Beware the locale

Feb 22nd

Posted by Silveira in english

No comments

Today I was programming a toString method for a class widely used in a application, using the very useful String.format that provides a C’s like printf formatter.

@Override
public String toString() {
   return String.format("VO[a: %.1f, b: %.1f, c: %.1f]", a, b, a+b);
}

%.1f means a float with one digit precision after the dot separator. The code produces something like:

VO[a: 1.0, b: 2.0, c: 3.0]

The problem arises when running a JUnit test on this method wrote using a regular expression to extract the values from the String to test it correctness. We cannot assume that the dot will be always the separator for displaying a float value, in my locale pt_BR would be a comma. So the output would be:

VO[a: 1,0, b: 2,0, c: 3,0]

For a predictable output we can set a Locale for String.format:

Locale en = new Locale("en");
return String.format(en, "VO[a: %.1f, b: %.1f, c: %.1f]", a, b, a+b);

So it will always use the dot as common separator. Of course you should follow and respect the localization and internationalization efforts in others moments but in this toString case we are using it internally for debug and unitary testing so we can set a English default locale for safety reasons.

development, i18n, Java, JUnit, locale, programming, String, teste unitário, toString, unit testing

Chaveiro Höfner 500

Feb 14th

Posted by Silveira in english

No comments

Chaveiro Höfner_500/1

Achei esse chaveiro miniatura do baixo-violino Höfner_500/1, o famoso baixo do Paul McCartney nos tempos dos Beatles. Por enquanto eu fico com o chaveiro mas um dia ainda vou ter uma réplica desse baixo.