Creating Alert dialogue boxes in Android:

public class ButtoneventActivity extends Activity implements View.OnClickListener {

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

                private Button b1;

                private Button b2;

                private Button b3;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        b1=(Button)findViewById(R.id.button1);

        b1.setText("Click");

        b1.setOnClickListener(this);

        b2=(Button)findViewById(R.id.button2);

        b2.setText("alert");

        b2.setOnClickListener(this);

        b3=(Button)findViewById(R.id.button3);

        b3.setText("Conform");

        b3.setOnClickListener(this);

    }

                @Override

                public void onClick(View view) {

                                // TODO Auto-generated method stub

                                if(view==b1){

                                                AlertDialog showAlert=new AlertDialog.Builder(this).create();

                                                 showAlert.setTitle("it's clicked");

                                                 showAlert.setMessage("are you sure you want to Burn?");

                                                 showAlert.setButton("Burn",new OnClickListener(){

                                                                @Override

                                              public void onClick(DialogInterface dialog, int which) {

                                                                   // TODO Auto-generated method stub

                                                                                dialog.cancel();

                                                                }                                                             

                                                  });

                                                 showAlert.show();                         

                                        }

                                else if(view==b2){

                                               AlertDialog showAlert=new AlertDialog.Builder(this).create();

                                                 showAlert.setTitle("Button clicked");

                                                 showAlert.setMessage("are you sure you want to save?");

                                                 showAlert.setButton("save",new OnClickListener() {

                                                                @Override

                                                 public void onClick(DialogInterface dialog, int which) {

                                                                    // TODO Auto-generated method stub

                                                                                 dialog.cancel();

                                                                }       

                                       });

                                                 showAlert.setButton2("Cancle",new OnClickListener(){

                                                                                @Override

                                            public void onClick(DialogInterface dialog, int which) {

                                                                  //TODO Auto-generated method stub

                                                                                                 dialog.cancel();

                                                                                                                                                                                                       

                                       }                                 

                             });

                                                 showAlert.show();

                                }

                                else if(view==b3){

                                                AlertDialog showAlert=new AlertDialog.Builder(this).create();

                                                 showAlert.setTitle("Button clicked");

                                                 showAlert.setMessage("are you sure you want to save?");

                                                 showAlert.setButton("Yes",new OnClickListener(){

                                                                @Override

                                                  public void onClick(DialogInterface dialog, int which) {

                                                                        // TODO Auto-generated method stub

                                                                                 dialog.cancel();

                                                                }               

                               });

                                                 showAlert.setButton2("NO",new OnClickListener(){

                                                                                @Override

                                                      public void onClick(DialogInterface dialog, int which) {

                                                                               // TODO Auto-generated method stub

                                                                                                 dialog.cancel();               

                                                                                }     

                                                           });

                                                 showAlert.setButton3("Cancle",new OnClickListener(){

                                                                                @Override

                                     public void onClick(DialogInterface dialog, int which) {

                                                                // TODO Auto-generated method stub

                                                                                                 dialog.cancel();

                                                                                }      

                                        });  

                                  showAlert.show();   

                                               }

                             }

    }

Passing Data from One Intent to Another Intent:

Here I used two Activity classes to pass data from one activity to another activity through Intents.

Main Activity.java :  which Intent send the data:

public class MainActivity extends Activity implements OnClickListener {

     EditText name, pwd;

                Button sub;

                @Override

                protected void onCreate(Bundle savedInstanceState) {

                                super.onCreate(savedInstanceState);

                                setContentView(R.layout.main);

                                name=(EditText)findViewById(R.id.NameText);

                                pwd=(EditText)findViewById(R.id.PassWordText);

                                sub=(Button)findViewById(R.id.button1);

                                sub.setOnClickListener(this);

                }

                @Override

                public void onClick(View v) {

                                String ename=name.getText().toString();

                                String epwd=pwd.getText().toString();

                                Intent intn=new Intent(MainActivity.this,SecondActivity.class);

// here putExtra(keyvalue,value); // here keyvalue is a key value to identify value from first intent in another intent. Value is value which you are passing to another intent.

                                intn.putExtra("Name",ename);

                                intn.putExtra( "PassW",epwd);

                                startActivity(intn);

                }       }

Second Activity.java: which receives that data and prints that data:

public class SecondActivity extends Activity implements OnClickListener{

                Button get,search;

                EditText nm,pw;

                String sname,spwd;

                @Override

                protected void onCreate(Bundle savedInstanceState) {

                                super.onCreate(savedInstanceState);

                                setContentView(R.layout.second);

                                get=(Button)findViewById(R.id.button);

                                nm=(EditText)findViewById(R.id.editName);

                                pw=(EditText)findViewById(R.id.editPassWord);

                                search=(Button)findViewById(R.id.Searchbutton);

                                search.setOnClickListener(this);

                                get.setOnClickListener(this);

//Bundle is using to get the intent extra fileds from passing intent.

                                Bundle b=getIntent().getExtras();

                                sname=b.getString("Name");

                                spwd=b.getString("PassW");

                }

                @Override

                public void onClick(View v) {

                                // TODO Auto-generated method stub

                                if(v==get){

                                nm.setText(sname);

                                pw.setText(spwd);

                                }

                                else if(v==search){

                                                Intent intn=new Intent(Intent.ACTION_VIEW);

                                                intn.setData(Uri.parse("http://www.google.com"));

                                                startActivity(intn);

                }              }               }