Sarmad's Blog: 2009

Monday 28 December 2009

Time Picker Example Android

Time Picker Example is completely similar to Date Picker example except that we explicitly add 0 with single digit number

Here's the java code

public class TimePicker extends Activity {

private TextView mTimeDisplay;
private Button mPickTime;

private int mHour;
private int mMinute;

static final int TIME_DIALOG_ID = 0;

   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);

   // capture our View elements
   mTimeDisplay = (TextView) findViewById(R.id.timeDisplay);
   mPickTime = (Button) findViewById(R.id.pickTime);

   // add a click listener to the button
   mPickTime.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
   showDialog(TIME_DIALOG_ID);
   }
   });

   // get the current time
   final Calendar c = Calendar.getInstance();
   mHour = c.get(Calendar.HOUR_OF_DAY);
   mMinute = c.get(Calendar.MINUTE);

   // display the current date
   updateDisplay();
   }

   @Override
   protected Dialog onCreateDialog(int id) {
   switch (id) {
   case TIME_DIALOG_ID:
   return new TimePickerDialog(this,
   mTimeSetListener, mHour, mMinute, false);
   }
   return null;
   }

// updates the time we display in the TextView
   private void updateDisplay() {
   mTimeDisplay.setText(
   new StringBuilder()
   .append(pad(mHour)).append(":")
   .append(pad(mMinute)));
   }

// the callback received when the user "sets" the time in the dialog
   private TimePickerDialog.OnTimeSetListener mTimeSetListener =
   new TimePickerDialog.OnTimeSetListener() {
   public void onTimeSet(android.widget.TimePicker view, int hourOfDay, int minute) {
   mHour = hourOfDay;
   mMinute = minute;
   updateDisplay();
   }

   };

   private static String pad(int c) {
   if (c >= 10)
   return String.valueOf(c);
   else
   return "0" + String.valueOf(c);
   }


Your main.xml should look like this

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">

<TextView android:id="@+id/timeDisplay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""/>

<Button android:id="@+id/pickTime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Change the time"/>

</LinearLayout>

Struts2 Double Click issue in Firefox

Problem:
The problem i faced was that some of my struts2 actions are being called twice or sometimes thrice in Firefox only when clicked once from my website or UI. This is the only place where IE was working perfectly fine and FF was troubling..lolz (and because of it i was more worried).

Symptoms:

I took myself in debugging mode and was seeing that actions are being called twice. Secondly my log4j logging was also proving this.

I used FireBug to see the how many hits are being generated and it showed that as soon as i clicked once on the hyperlink, two (or three in one case) hits generated. So the issue was finally proved that it is due to some UI stuff.

Due to it for a glimpse of a second i was being shown some validation error(as when the form is submitted second time, it was submitted with null values) plus things got worst when my code started showing exception(Due to null values)

Solution:

After googling for a week(although for sometime i dropped this issue and got involved in other but it took a week) i found its solution that this happens due to empty image tag <img src=""/>

but the thing was i wasnt using any empty image tag in the whole page. But after some help i figured it out that it was due to background-image

Actually it happens because for images another call is being generated and as we are specifying that background image is null therefore it was hitting the default action we were specifying in s:submit tag

About server being hit thrice, i did a mistake that instead of defining just only href or onClick...i defined both of them. So the problem got resolved when i remove one of them

Sunday 27 December 2009

Date Picker Example Android

In this example im making one of the most simplest program on Android which is Date Picker. You can change the date which is being displayed in a Text View(Remember Text View is just like labels in HTML)

Here is the java code for it...

public class datePicker extends Activity {

private TextView mDateDisplay;
   private Button mPickDate;

   private int mYear;
   private int mMonth;
   private int mDay;

   static final int DATE_DIALOG_ID = 0;


   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);

   // capture our View elements
   mDateDisplay = (TextView) findViewById(R.id.dateDisplay);
   mPickDate = (Button) findViewById(R.id.pickDate);

   // add a click listener to the button
   mPickDate.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
   showDialog(DATE_DIALOG_ID);
   }
   });

   // get the current date
   final Calendar c = Calendar.getInstance();
   mYear = c.get(Calendar.YEAR);
   mMonth = c.get(Calendar.MONTH);
   mDay = c.get(Calendar.DAY_OF_MONTH);

   // display the current date
   updateDisplay();
   }

As you can see first we are getting or capturing front end controls in our Java variables and then we have defined a OnClickListen event on button click...

CreateDialog method is responsible of opening a window which has a GUI related to date.

@Override
   protected Dialog onCreateDialog(int id) {
   switch (id) {
   case DATE_DIALOG_ID:
   return new DatePickerDialog(this,
   mDateSetListener,
   mYear, mMonth, mDay);
   }
   return null;
   }

// the callback received when the user "sets" the date in the dialog
   private DatePickerDialog.OnDateSetListener mDateSetListener =
   new DatePickerDialog.OnDateSetListener() {

   public void onDateSet(DatePicker view, int year,
   int monthOfYear, int dayOfMonth) {
   mYear = year;
   mMonth = monthOfYear;
   mDay = dayOfMonth;
   updateDisplay();
   }
   };

@Override
   protected Dialog onCreateDialog(int id) {
   switch (id) {
   case DATE_DIALOG_ID:
   return new DatePickerDialog(this,
   mDateSetListener,
   mYear, mMonth, mDay);
   }
   return null;
   }

Now your main.xml should look like this

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">

<TextView android:id="@+id/dateDisplay"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""/>

<Button android:id="@+id/pickDate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Change the date"/>

</LinearLayout>

Table Layout Example Android

Table Layout is the third and the last layout available in Android OS. This is very similar to Excel sheet or html tabular form.

To implement this Layout your java file should look like this...

public class TableLayout extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

and your main.xml which is in res/layout should look like this

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:stretchColumns="1">

<TableRow>
<TextView
android:layout_column="1"
android:text="Open..."
android:padding="3dip" />
<TextView
android:text="Ctrl-O"
android:gravity="right"
android:padding="3dip" />
</TableRow>

<TableRow>
<TextView
android:layout_column="1"
android:text="Save..."
android:padding="3dip" />
<TextView
android:text="Ctrl-S"
android:gravity="right"
android:padding="3dip" />
</TableRow>

<TableRow>
<TextView
android:layout_column="1"
android:text="Save As..."
android:padding="3dip" />
<TextView
android:text="Ctrl-Shift-S"
android:gravity="right"
android:padding="3dip" />
</TableRow>

<View
android:layout_height="2dip"
android:background="#FF909090" />

<TableRow>
<TextView
android:text="X"
android:padding="3dip" />
<TextView
android:text="Import..."
android:padding="3dip" />
</TableRow>

<TableRow>
<TextView
android:text="X"
android:padding="3dip" />
<TextView
android:text="Export..."
android:padding="3dip" />
<TextView
android:text="Ctrl-E"
android:gravity="right"
android:padding="3dip" />
</TableRow>

<View
android:layout_height="2dip"
android:background="#FF909090" />

<TableRow>
<TextView
android:layout_column="1"
android:text="Quit"
android:padding="3dip" />
</TableRow>
</TableLayout>

Relative Layout Example Android

Here's the demo of another Android layout. In this layout everything or every control is kept with the relative of the other control. In this layout you can specifically tell that keep your new control at a particular place with respect of that particular control by use of "android:layout_toLeftOf" similarly toRightOf and etc are available.

Java code is very simple...

public class RelativeLayout extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

Your main.xml should look like this which is present in res/layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Type here:"/>

<EditText
android:id="@+id/entry"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@android:drawable/editbox_background_normal"
android:layout_below="@id/label"/>

<Button
android:id="@+id/ok"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/entry"
android:layout_alignParentRight="true"
android:layout_marginLeft="10dip"
android:text="OK" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toLeftOf="@id/ok"
android:layout_alignTop="@id/ok"
android:text="Cancel" />

</RelativeLayout>

Linear Layout Example Android

Linear Layout is the simplest layout of Android. It depends which type of orientation you have set. If it is set to LinearLayout.Vertical then the inserted controls will be in vertical order else in horizontal.

Here's the code through which you can implement this easiest layout of android

In your java file write this code...

public class TestLinearLayout extends Activity {
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
   }
}

and in your main.xml which is in res/layout write this code

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>

<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1">

<TextView
android:text="red"
android:gravity="center_horizontal"
android:background="#aa0000"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>

<TextView
android:text="green"
android:gravity="center_horizontal"
android:background="#00aa00"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>

<TextView
android:text="blue"
android:gravity="center_horizontal"
android:background="#0000aa"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>

<TextView
android:text="yellow"
android:gravity="center_horizontal"
android:background="#aaaa00"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>

</LinearLayout>

<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1">

<TextView
android:text="row one"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

<TextView
android:text="row two"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

<TextView
android:text="row three"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

<TextView
android:text="row four"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

</LinearLayout>

</LinearLayout>