Android Spinner Example

In this example we will see how to work with spinners in android. Spinners are used for selecting one value from a given set like the drop down list. We will create dependent spinner i.e the entries of the second spinner depends on the value selected in the first spinner.

In this sample application we will have two spinner first one for selecting country and the other for selecting city. Depending on the country selected in the first spinner the cities in the second spinner changes.

Lets start:

1.Create an Android Application Project (File->New->Android Application Project). While creating the project name the Activity as MainActivity(MainActivity.java) and the layout file as activity_main (activity_main.xml).

2.When done with creating the project add array resources to your strings.xml file in res/values folder which will serve as the data source for the spinners.

strings.xml:

<resources>

<string name="app_name">Spinner</string>
<string name="hello_world">Hello world!</string>
<string name="title_activity_main">MainActivity</string>

<string-array name="country_array">
<item>India</item>
<item>Pakisthan</item>
<item>Sri Lanka</item>
</string-array>
<string-array name="city_india">
<item>Mumbai</item>
<item>Chennai</item>
<item>Kolkata</item>
<item>Bangalore</item>
</string-array>
<string-array name="city_pakisthan">
<item>Karachi</item>
<item>Lahore</item>
<item>Faisalabad</item>
<item>Rawalpindi</item>
</string-array>
<string-array name="city_srilanka">
<item>Colombo</item>
<item>Dehiwala-Mount Lavinia</item>
<item>Moratuwa</item>
<item>Kotte</item>
</string-array>
</resources>

3.Design the UI with a TextView & two Spinners and assign default entries for the spinners.

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="left" >

<TextView
android:id="@+id/textView"
android:layout_width="130dp"
android:layout_height="50dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:gravity="center"
android:text="Select County and City"
android:textSize="15dp"
/>

<Spinner
android:id="@+id/spinnerCountry"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView"
android:layout_centerHorizontal="true"
android:layout_marginTop="28dp"
android:entries="@array/country_array" />

<Spinner
android:id="@+id/spinnerCity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/spinnerCountry"
android:layout_below="@+id/spinnerCountry"
android:layout_marginTop="42dp"
android:entries="@array/city_india" />

</RelativeLayout>

4.Now in the Activity file we will create the spinners instances and change the adapters data-source for the second spinner(city) depending on the value selected in the first spinner(country). This is done in the onItemSelected callback method of the first spinner.

MainActivity.java:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class MainActivity extends Activity implements OnItemSelectedListener {

 Spinner spinnerCountry, spinnerCity;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  spinnerCountry = (Spinner) findViewById(R.id.spinnerCountry);
  spinnerCity = (Spinner) findViewById(R.id.spinnerCity);
  spinnerCountry.setOnItemSelectedListener(this);
 }

 @Override
 public void onItemSelected(AdapterView<?> parent, View arg1, int pos,
   long arg3) {
  parent.getItemAtPosition(pos);
  if (pos == 0) {
   ArrayAdapter<CharSequence> adapter = ArrayAdapter
     .createFromResource(this, R.array.city_india,
       android.R.layout.simple_spinner_item);
   spinnerCity.setAdapter(adapter);
  } else if (pos == 1) {
   ArrayAdapter<CharSequence> adapter = ArrayAdapter
     .createFromResource(this, R.array.city_pakisthan,
       android.R.layout.simple_spinner_item);
   spinnerCity.setAdapter(adapter);
  } else if (pos == 2) {
   ArrayAdapter<CharSequence> adapter = ArrayAdapter
     .createFromResource(this, R.array.city_srilanka,
       android.R.layout.simple_spinner_item);
   spinnerCity.setAdapter(adapter);
  }
 }

 @Override
 public void onNothingSelected(AdapterView<?> arg0) {
 }
}

5.Run the application by right clicking the project Run As->Android Application. You would see and output similar to the one below

Output:

 

Android Display Running Application Process Programmatically – Example

In this post we will see how to display all the running application process in a device or emulator.  It can be done by creating an instance for the ActivityManager Class . In this sample application we will get the list of running app process in a List and will display it in a TextView .


So lets start:

1.Create a new project File ->New -> Project ->Android ->Android Application Project. While creating the new project, name the activity as MainActivity(MainActivity.java)and layout as activity_main.xml.

2.Now let us design the UI for the MainActivity i.e activity_main.xml with a TextView.

activity_main.xml:

<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"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Running Apps \n" />

</RelativeLayout>

3.Now in the MainActivity use ActvityManager instance and get the appropriate system service and list them in a textview.

MainActivity.java:

package com.example.piolt;

import java.util.List;

import android.app.Activity;
import android.app.ActivityManager;
import android.app.ActivityManager.RunningAppProcessInfo;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  TextView tv = (TextView) findViewById(R.id.textView);

  ActivityManager activityManager = (ActivityManager) this
    .getSystemService(ACTIVITY_SERVICE);

  List<RunningAppProcessInfo> procInfos = activityManager
    .getRunningAppProcesses();
  for (int idx = 0; idx < procInfos.size(); idx++) {

   tv.setText(tv.getText() + "" + (idx + 1) + "."
     + procInfos.get(idx).processName + "\n");

  }

 }

}

4.Run the project by rightclicking project Run as → android project in an android device.

Output:

The output of this example would be similar to the one as follows: