Skip to main content

Displaying a Dialog Window

There are times when 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 Activity base class to display a dialog window. The following Try It Out shows you how.

1. Using Android Studio , create a new Android project and name it Dialog. When presented with the option , name the main activity DialogActivity.

2.Add the following theme in bold to the AndroidMainfest.xml file. Be sure to change all instances of "com.android" to whatever package name your project is using.

<?xml version="1.0" encoding="utd-8"?>
<manifest xmlns:android"http://schemas.android.com/apk/res/android" package="com.android.dialog">
     <application
          android:allowBackup="true"
          android:icon:="@mipmap/ic_launcher"
          android:label="@String/app_name"
          android:supportRtl="true"
          android:theme="@style/AppTheme" >
          <activity
               android:name=".DialogActivity"
               android:label="@string/app_name"
               android:theme="@style/Theme.AppCompat.Dialog" >
               <intent-filter>
                      <action android:name="android.intent.action.MAIN" />
                      <category android:name="android.intent.category.LAUNCHAR" />
               < / intent-filter>
          </activity>
     </application>
</manifest>

3. Compare your DialogActivity.java file to this:

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snacbar;
import android.support.v7.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.MenuItem;

public class DialogActivity extends AppCompatActivity
{
             @Override
             protected void onCreate(Bundle saveIntanceState)
             {
                         super.onCreate(saveInstaceState);
                         setContentView(R.layout.activity_dialog);
                         Toolbar toolbar=(Toolbar)findViewById(R.id.toolbar);
                         setSupportActionBar(toolbar);
 
                         FloatingActionButton fat = (FloatingActionButton) findViewById(R.id.fab);
                         fab.setOnclickListener(new View.OnClickListener() {
                                 @Override
                                 public void onClick(View view)
                                 {
                                         Snackbar.make(view, "Replace with your own action" ,
                                              Snackbar.LENGTH_LONG)
                                                      .setAction("Action",null).show();
                                  }
                         });
               }
              @Override
               public boolean onCreateOpationsMenu(Menu menu)
               {
                        // Inflate the menu; this adds items to the action bar if it is present.
                        getMenuInflater().inflate(R.menu_dialog, menu);
               }
              @Override
              public boolean onOpationItemSelected(MenuItem item)
              {
                      //Handle action bar Item clicks here. The action Bar will
                      //automatically handle clicks on the Home/Up button, so long
                      //as you specify a parent activity in AndroidManifest.xml.

                      int id = item.getItemId();

                      //notinspection SimplifiableIfStatement
                      if ( id == R.id.action_settings)
                      {
                                 return true;
                      }

                      return super.onOpationsItemSelected(item);
               }
}

4. Press Shift+F9 to debug the application on the Android emulator. Click the button to display the dialog.

How It Works

Android uses the Appcompat.Dialog theme to draw your standard activity as a free-floating dialog box.It would be very easy to modify this dialog to add some buttons if you needed to provide an OK or Cancel choice.

Notice also that theme is applied to the Activity , not the project. Therefore , you could have a project with multiple activities , and apply the dialog theme to just one of them.

Comments

Popular posts from this blog

Creating Android Virtual Devices (AVDs)

The next step is to create an Android Virtual Device (AVD) you can use for testing your Android application. An AVD is an emulator instance that enables you to model an actual device. Each AVD consists of a hardware profile ; a mapping to a system image ; and emulated storage,such as a secure digital (SD) card.One important thing to remember about emulators is that they are not perfect. There are some applications , such as games (which are GPU heavy ) or application that use sensors such as the GPS or accelerometer. Theses types of application cannot be simulated with the same speed or consistency within an emulator as they can when running on an actual device. However , the emulator is good for doing some generalized testing of your applications. You can create as many AVDs as you want to test your applications with different configurations. This testing is important to confirm the behavior of you application when it is run on different devices with varying capabilities. Use ...

Hiding the Activity Title

You can also hide the title of an activity if desired ( Such as when you just want to display a status update to the user). To do so , use the requestWindowFeature() method and pass it the window .FEATURE_NO_TITLE constant, like This : import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Window; public class MainActivity extends AppCompatActivity{            @Override            protected void onCreate ( Bundle savedInstanceState )            {                         super.onCreate (savedInstanceState );                         setContentView (R.layout.activit...

Applying Styles and Themes to an Activity

By default , an activity is themed to the default Android theme. However , there been a push in recent year to adopt a new theme known as Material . The Material theme has a much more modern and clean look to it. There are two versions of the Material theme available to Android developers : Material Light and Material Dark , Either of these themes can be applied from the AndroidManifest.xml To apply one of the Material themes to an activity , simply modify the <Application> element in the AndroidManifest.xml file by changing the default android:theme attribute. (Please be sure to change all instances of "com.android" to whatever package name your project is using.) <?xml version="1.0" encoding="utf-8"?> <manifest xmls:android="http://schemas.android.com/apk/res/android"        xmlns:tools="http://schemas.android.com/tools"        package="com.android.activity101">        <application ...