New Android SDK is released!

If you saw the screen of the previous Android SDK before, you will quickly find out that this new Android SDK released is so different from looking and operating now. I learned some information about the previous SDK that had some bugs found by the community. So I think Android this time provides new SDK version for fixing the bugs, update APIs, and also enhances some basic functions, for instance maps application as following pictures:

The new desktop of Android platform

Maps application's new feature (zoom in)

I find my home in Taiwan...

A simple Google Android application Part II

In Android framework, Activity class just like MIDlet in Java ME, it provides a frame to display the UI or perform a task. To layout the widgets on Activity, we can use xml file to achieve that. This example has 2 Activity classes, MainActivity.java and Queen.java, each has xml file to define the widgets and layout. In Queen.java, it uses recursive method to solve the N x N Queen problem. Due to the algorithm is not relevant to Android platform, so I emit the most source code with the algorithm and only put the method putQtoArray() to show recursive way.as follows:

main.xml


<Button android:id="@+id/MainButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="OK"
android:layout_x="10px" android:layout_y="102px">
</Button>


<Button android:id="@+id/MainButton2"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="Cancel"
android:layout_x="80px" android:layout_y="102px">
</Button>




queen.xml:




<Button android:id="@+id/QueenButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="OK"
android:layout_gravity="right">
</Button>


MainActivity.java

package csu.android.applications;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.EditText;

import android.text.method.*;

import android.view.View.OnClickListener;

import android.widget.Button;

public class MainActivity extends Activity {

private EditText myEText;

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle icicle) {

super.onCreate(icicle);

setContentView(R.layout.main);

myEText = (EditText) findViewById(R.id.MainEditText1);

myEText.setInputMethod(DigitsInputMethod.getInstance());

Button okButton = (Button) findViewById(R.id.MainButton1);

Button cancelButton = (Button) findViewById(R.id.MainButton2);

okButton.setOnClickListener(mOKListener);

cancelButton.setOnClickListener(mCancelListener);

}

private OnClickListener mOKListener = new OnClickListener() {

public void onClick(View v) {

String tmp = myEText.getText().toString();

if (!myEText.getText().toString().equals("")) {

int Qnum = Integer.parseInt(tmp);

if (Qnum <= 9) {

// Here we start up the main entry point

Intent intent = new Intent(MainActivity.this, Queen.class);

intent.putExtra("NumKey", tmp);

startActivity(intent);

finish();

} else {

showAlert("The number is bigger than 9!", 0, "Try again!",

"OK", true);

myEText.setText("");

return;

}

}

}

};

private OnClickListener mCancelListener = new OnClickListener() {

public void onClick(View v) {

myEText.setText("");

}

};

}

Queen.java

package csu.android.applications;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import java.util.*;

public class Queen extends Activity {

EditText myEText;

int QueenNum;

int totalcount = 0; // the total number of distinct results.

int uniquecount = 0; // the total number of unique results.

boolean[][] arr;

// Record the scores for mapping

ArrayList al;

// For check the duplicate solutions

int[][] arrRotation0;

int[][] arrRotation90;

int[][] arrRotation180;

int[][] arrRotation270;

int[][] arrMirror;

private StringBuilder sb;

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle icicle) {

super.onCreate(icicle);

setContentView(R.layout.queen);

myEText = (EditText) findViewById(R.id.QueenEditText1);

Button backButton = (Button) findViewById(R.id.QueenButton1);

backButton.setOnClickListener(this.mBackListener);

Bundle extras = getIntent().getExtras();

if (extras != null) {

QueenNum = Integer.parseInt(extras.getString("NumKey"));

startCalculation();

myEText.setText(sb.toString());

} else {

showAlert("There is no input!", 0, "Click me", "OK", true);

Intent intent = new Intent(Queen.this, MainActivity.class);

startActivity(intent);

finish();

}

}

private OnClickListener mBackListener = new OnClickListener() {

public void onClick(View v) {

Intent intent = new Intent(Queen.this, MainActivity.class);

startActivity(intent);

finish();

}

};

/*

* startCalculation This method implements recursion for N*N Queen problem.

*/

public void startCalculation() {

sb = new StringBuilder();

// Array for N*N Queens problem

arr = new boolean[QueenNum][QueenNum];

// Array for calculating the duplicate result.

arrRotation0 = new int[QueenNum][QueenNum];

arrRotation90 = new int[QueenNum][QueenNum];

arrRotation180 = new int[QueenNum][QueenNum];

arrRotation270 = new int[QueenNum][QueenNum];

arrMirror = new int[QueenNum][QueenNum];

al = new ArrayList();

// Prepare random numbers inserted into arrays

// for the calculation of the duplication .

prepareRotationData();

// Do recursions

putQtoArray(QueenNum - 1);

}

/*

* putQtoArray This method implements recursion for N*N Queen problem.

* @param: QueenNum

*/

public void putQtoArray(int myNum) {

if (myNum == -1) {

// Find a distinct result.

totalcount++;

// Display the result.

showMe();

return;

}

for (int i = 0; i <>

if (!checkRule(i, myNum)) {

arr[i][myNum] = true;

// Recursion

putQtoArray(myNum - 1);

arr[i][myNum] = false;

}

}

}

... ... rest of part is omitted ... ...

}

Because Activity "Queen" will be started by Activity "MainActivity" using Intent, we also need to add a line into AndroidManifest.xml as below, then that is all set. <activity android:name="Queen" android:label="@string/app_name">

A simple Google Android application Part I

What is Google Android? I don't need to babble that... because I think that it will be very clear if you see this : http://code.google.com/android/what-is-android.html

Basically, Android includes Linux kernel as operating system, libraries ( C language), Android runtime ( Dalvik virtual machine for Java byte code), and application framework (APIs for Java) . The applications we wanna develop are based on this application framework and Java 1.5 language specification, and will run on Android runtime.

Until now, Google only has prototype cell phone for running Android platform. Due to this reason, all the applications need to execute on the emulator which emulates the same environment just like you really have the hardware. There is a simple example that can give an idea about developing a Android application.

This example will ask you a number for defining N x N Queen problem.
Then it will calculate the possibility of results showing as a simple checker.

P.S: It runs on the Android emulator.

[Android] DroidDraw

Dealing with the widgets and layouts in the Android project is a tedious work, especially Eclipse plug-in Android right now doesn't have visual tool for developers to construct the interfaces.
All the things need to do with XML. Fortunately, there is a tool that is very useful to it.
It also provides tutorials that developers can quickly understand how to use it.

http://www.droiddraw.org/