Android

One & Only best book/source to start working on Android:
SDK: http://developer.android.com/sdk/index.html
Dev Guide: http://developer.android.com/guide/basics/what-is-android.html
Videos: http://developer.android.com/videos/index.html#v=opZ69P-0Jbc

My Learning (Errors that I faced):
INSTALL_PARSE_FAILED_MANIFEST_MALFORMED:
During creating an android project, I faced an issue after adding a Data-Base i.e.
"INSTALL_PARSE_FAILED_MANIFEST_MALFORMED".
After analysis, I came to know that permission was not provided in Manifest file.
Wrong way: android:name = ". DataBase"
Correct way: android:name = ". DataBase" android:authorities="com.android. Entries"
Please take care of this for your project.
Conversion to Dalvik format failed with error 1:

I faced this error, then I removed all unused Libraries from "Java Build Path" and kept only required library. Finally it start working. :)

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Tab Widgets:

TabHost contains two items:

1. TabWidget has the row of tab buttons
2. FrameLayout contains tab contents

There are two ways are there to create Tab Widgets:

1. By extending  “TabActivity”:
Acquire.java:

package com.android.wg;

import android.app.TabActivity;

import android.content.res.Resources;

import android.os.Bundle;

import android.widget.TabHost;

public class Acquire extends TabActivity {

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

      @Override

      public void onCreate(Bundle savedInstanceState) {   

            super.onCreate(savedInstanceState);   

          setContentView(R.layout.tabwidget);

          TabHost MyTabs = getTabHost();

          Resources res = getResources(); // Resource object to get Drawables

          MyTabs.addTab(MyTabs.newTabSpec("Tab1")

                                    .setIndicator("TAB 1",res.getDrawable(android.R.drawable.btn_star))

                                    .setContent(R.id.textviewTab1));

          MyTabs.addTab(MyTabs.newTabSpec("Tab2")

                        .setIndicator("TAB 2",res.getDrawable(android.R.drawable.btn_star))

                        .setContent(R.id.textviewTab2));

          MyTabs.setCurrentTab(0);

      }

}

Tabwidget.xml:

<?xml version="1.0" encoding="utf-8"?>

<TabHost xmlns:android="http://schemas.android.com/apk/res/android"    

android:id="@android:id/tabhost"   

android:layout_width="fill_parent"   

android:layout_height="fill_parent">   

   <LinearLayout       

      android:orientation="vertical"       

      android:layout_width="fill_parent"

      android:layout_height="fill_parent">

      <TabWidget

            android:id="@android:id/tabs"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"

      />

      <FrameLayout

            android:id="@android:id/tabcontent"

            android:layout_width= "fill_parent"

            android:layout_height="fill_parent">

            <TextView                

                  android:id="@+id/textviewTab1"               

                  android:layout_width="fill_parent"               

                  android:layout_height="fill_parent"                

                  android:text="You are in Tab 1" />

            <TextView                

                  android:id="@+id/textviewTab2"               

                  android:layout_width="fill_parent"               

                  android:layout_height="fill_parent"                

                  android:text="You are in Tab 2" />

      </FrameLayout>

   </LinearLayout>

</TabHost>

2. By extending  “Activity”:

Acquire.java:

package com.android.wg;

import android.app.Activity;

import android.content.res.Resources;

import android.os.Bundle;

import android.widget.TabHost;

public class Acquire extends Activity {

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

      @Override

      public void onCreate(Bundle savedInstanceState) {   

            super.onCreate(savedInstanceState);   

          setContentView(R.layout.tabwidget);

          Resources res = getResources(); // Resource object to get Drawables

          TabHost MyTabs = (TabHost)findViewById(R.id.tabhost);

          MyTabs.setup();

         

          MyTabs.addTab(MyTabs.newTabSpec("Tab1")

                                    .setIndicator("TAB 1",res.getDrawable(android.R.drawable.btn_star))

                                    .setContent(R.id.textviewTab1));

          MyTabs.addTab(MyTabs.newTabSpec("Tab2")

                        .setIndicator("TAB 2",res.getDrawable(android.R.drawable.btn_star))

                        .setContent(R.id.textviewTab2));

          MyTabs.setCurrentTab(0);

      }

}

/*

Below Code:

MyTabs.addTab(MyTabs.newTabSpec("Tab1")

                                    .setIndicator("TAB 1",res.getDrawable(android.R.drawable.btn_star))

                                    .setContent(R.id.textviewTab1));

can be used as:

TabHost.TabSpec TSpec;

TSpec =tabs.newTabSpec("Tab1");

TSpec.setIndicator("TAB 1",res.getDrawable(android.R.drawable.btn_star));

TSpec.setContent(R.id.textviewTab1);

MyTabs.addTab(TSpec);

*/

Tabwidget.xml:

<?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">

   <TabHost

        android:id="@+id/tabhost"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent">

      <TabWidget

            android:id="@+id/tabs"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"

      />

      <FrameLayout

            android:id="@+id/tabcontent"

            android:layout_width="fill_parent"

            android:layout_height="fill_parent"

            android:paddingTop="62px">

            <TextView                

                  android:id="@+id/textviewTab1"               

                  android:layout_width="fill_parent"               

                  android:layout_height="fill_parent"                

                  android:text="You are in Tab 1" />

            <TextView                

                  android:id="@+id/textviewTab2"               

                  android:layout_width="fill_parent"               

                  android:layout_height="fill_parent"                

                  android:text="You are in Tab 2" />

      </FrameLayout>

   </TabHost>

</LinearLayout>

Android Link: http://developer.android.com/resources/tutorials/views/hello-tabwidget.html
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XmlPullParser:

XML Pull Parser is an interface that defines parsing functionality.

Basically used methods & Events in parsing:

next:                            provides access to high level parsing events.

nextToken():               provides access to lower level tokens.

getEventType():          determine current event state of the parser.

getName():                  provide the tag name of current event.

Various Event types [that comes a output of getEventType() or next()]

START_DOCUMENT:          Starting of Document.

END_DOCUMENT:              End of Document.

START_TAG:                        Starting of Tag (e.g. <foo>)

END_TAG:                             End of Tag (e.g. </foo>)

TEXT:                                     State in between of Start Tag & End Tag.

Example:

import java.io.IOException;  import java.io.StringReader;  import org.xmlpull.v1.XmlPullParser;  import org.xmlpull.v1.XmlPullParserException.html;  import org.xmlpull.v1.XmlPullParserFactory;  public class SimpleXmlPullApp  {      public static void main (String args[])          throws XmlPullParserException, IOException      {          XmlPullParserFactory factory = XmlPullParserFactory.newInstance();          factory.setNamespaceAware(true);          XmlPullParser xpp = factory.newPullParser();          xpp.setInput( new StringReader ( "<foo>Hello World!</foo>" ) );          int eventType = xpp.getEventType();          while (eventType != XmlPullParser.END_DOCUMENT) {           if(eventType == XmlPullParser.START_DOCUMENT) {               System.out.println("Start document");           } else if(eventType == XmlPullParser.END_DOCUMENT) {               System.out.println("End document");           } else if(eventType == XmlPullParser.START_TAG) {               System.out.println("Start tag "+xpp.getName());           } else if(eventType == XmlPullParser.END_TAG) {               System.out.println("End tag "+xpp.getName());           } else if(eventType == XmlPullParser.TEXT) {               System.out.println("Text "+xpp.getText());           }           eventType = xpp.next();          }      }  }

Output: Start document  Start tag foo  Text Hello World!  End tag foo

Android Link: http://developer.android.com/reference/org/xmlpull/v1/XmlPullParser.html
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