Displaying a dialog using an activity in android tutorial

Displaying a dialog using an activity in android tutorial.

There are times where you need to display a dialog window to get a confirmation from the user. In 

this case, you can override the onCreateDialog()protected method defined in the base Activity

class to display a dialog window. The following Try It Out shows you how.

Now, create a new android project.

Edit interface in activity_main.xml file:

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

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.example.demoshowdialog.MainActivity" >

    <Button

        android:id="@+id/btnShow_Dialog"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="Show Dialog" />

</RelativeLayout>

Next, the proccess code in MainActivity.java file:

package com.example.demoshowdialog;

import android.app.Activity;

import android.app.AlertDialog;

import android.app.Dialog;

import android.content.DialogInterface;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

public class MainActivity extends Activity {

       private Button btnShow_Dialog;

       CharSequence[] items = { "Asus", "Acer", "Dell", "Vaio" };

       boolean[] bool = new boolean[items.length];

       @Override

       protected void onCreate(Bundle savedInstanceState) {

          super.onCreate(savedInstanceState);

          setContentView(R.layout.activity_main);

          btnShow_Dialog = (Button) findViewById(R.id.btnShow_Dialog);

          btnShow_Dialog.setOnClickListener(new OnClickListener() {

             @Override

             public void onClick(View v) {

                 showDialog(0);

             }

          });

       }

       @Override

       protected Dialog onCreateDialog(int id) {

          // TODO Auto-generated method stub

          switch (id) {

          case 0:

              return new AlertDialog.Builder(this)

              .setIcon(R.drawable.ic_launcher)

              .setTitle("Show Dialog Demo")

              .setPositiveButton("Yes",new DialogInterface.OnClickListener() {

                             @Override

                             public void onClick(DialogInterface dialog,int which) {

                             // TODO Auto-generated method stub

                             }

                   })

              .setNegativeButton("No",new DialogInterface.OnClickListener() {

                             @Override

                             public void onClick(DialogInterface dialog, int which) {

                             // TODO Auto-generated method stub

                             }

                   })

              .setMultiChoiceItems(items, bool,new DialogInterface.OnMultiChoiceClickListener() {

              @Override

              public void onClick(DialogInterface dialog,int which, boolean isChecked) {

                                                              // TODO Auto-generated method stub

                    }

              }).create();

              }

              return null;

       }

}

Explain:
To display a dialog, you first override the onCreateDialog() method in the Activity class

@Override

       protected Dialog onCreateDialog(int id) {

...

}
This method is called when you call the showDialog() method

btnShow_Dialog = (Button) findViewById(R.id.btnShow_Dialog);

              btnShow_Dialog.setOnClickListener(new OnClickListener() {

                     @Override

                     public void onClick(View v) {

                           showDialog(0);

                     }

              });

The onCreateDialog() method is a callback for creating dialogs that are managed by the activity. When you call the showDialog() method, this callback will be invoked. The showDialog() method accepts an integer argument identifying a particular dialog to display.

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