How to refresh Singleton class every one hour in android?

Before getting into example, we should know what singleton design patter is. A singleton is a design pattern that restricts the instantiation of a class to only one instance. Notable uses include controlling concurrency, and creating a central point of access for an application to access its data store.

This example demonstrate about How to refresh Singleton class every one hour in android

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = ""
   xmlns:tools = ""
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity"
   android:orientation = "vertical">
      android:id = "@+id/show"
      android:text = "refresh singleTone"
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content" />

In the above code, we have taken a button. When user click on the show button, it will show the toast.

Step 3 − Add the following code to src/

package com.example.andy.myapplication;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import org.json.JSONException;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
   Button show;
   JSONObject jsonObject;
   singleTonExample singletonexample;
   protected void onCreate(Bundle savedInstanceState) {
      show = findViewById(;
      singletonexample = singleTonExample.getInstance();
      show.setOnClickListener(new View.OnClickListener() {
         public void onClick(View v) {
            Toast.makeText(MainActivity.this,"Refersh Singlton class every one hour", Toast.LENGTH_LONG).show();

In the above code, we have used singleTonExample as a singleton class. So create a call as and add the following code -

package com.example.andy.myapplication;
import android.content.Context;
import java.util.Timer;
import java.util.TimerTask;
public class singleTonExample {
   private static singleTonExample ourInstance = new singleTonExample();
   static {
      Timer timer = new Timer();
      timer.schedule(new TimerTask() {
         public void run() {
            synchronized (singleTonExample.class) {
               ourInstance = new singleTonExample();
      }, 60 * 60 * 1000L /* Once per hour */);
   private Context appContext;
   private singleTonExample() { }
   public static Context get() {
      return getInstance().getContext();
   public static synchronized singleTonExample getInstance() {
      return ourInstance;
   public void init(Context context) {
      if (appContext == null) {
         this.appContext = context;
   private Context getContext() {
      return appContext;

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –

Now click on above button, it will show toast as shown below –

Click here to download the project code

Updated on: 30-Jul-2019


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