Monthly Archives: April 2011

Importing existing Java Project into Eclipse – “Create project from existing source”

Eclipse

Are you trying to import a non-Eclipse based Java project into Eclipse?

You find a lot of tips in the internet which tell you that you should create a new Java Project and then use the “Create project from existing source” option.

For example on the Google Plugin for Eclipse webpage.

Unfortunately this option does not exists. To my knowlegge the correct (and unfortunately a bit complex way) is to create a nwe Java project, select the project, right-click on it and select Import -> File System.

On the following dialog you can select the directory from which you want to import and also if existing resources should be overriden.

I hope this helps.

Remark: For Google App Engine with Java you also need to set the output path (bin folder) of the project to “projectname/war/WEB-INF/classes”.

One of a kind – getting the unique id which identifies the Android device

Android

Each Android devices allow to read the device settings via the class “Secure”. Especially for C2DM you have a need to uniquely identify the Android device so that you do not register the device several times for Cloud-to-device-messaging. From the Javadoc of “android.provider.Settings.Secure.ANDROID_ID”:

A 64-bit number (as a hex string) that is randomly generated on the device’s first boot and should remain constant for the lifetime of the device. (The value may change if a factory reset is performed on the device.)

Here is a little Activity which read this device identifier and shows it as a Toast.

package de.vogella.android.deviceinfo;

import android.app.Activity;
import android.os.Bundle;
import android.provider.Settings.Secure;
import android.widget.Toast;

public class ShowDeviceInfo extends Activity {
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		String deviceId = Secure.getString(this.getContentResolver(),
				Secure.ANDROID_ID);
		Toast.makeText(this, deviceId, Toast.LENGTH_SHORT).show();
	}
}

This way you can make sure that certain thing a uniquely defined for your device.

The penalty is death – StrictMode in Android

Android

Within Android development you should avoid performing long running operations on the UI thread. This includes file and network access.

But sometimes it is difficult to remember to make all the right things in your application during development. That is were StrictMode comes in. It allows to setup policies in your application to avoid doing incorrect things. For example the following setup will crash your application if it violates some of the Android policies. StrictMode should only be used during development and not in your live application. 

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
	.detectAll().penaltyLog().penaltyDeath().build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectAll()
	.penaltyLog().penaltyDeath().build());

For an introduction to background processing in Android see Android Background Processing Tutorial. More information about StrictMode can be found here.