Android is an open-source operating system, based on the Linux kernel and used in mobile devices like smartphones, tablets, etc. Further, it was developed for smartwatches and Android TV. In this article, we are going to see how we can implement static methods in Android. We will be creating static methods to display Toast, AlertDialog, and redirect to any other activity.
What we are going to build in this article?
Here is a sample video of what we are going to build in this article. Note that we are going to implement this project in the Java language.
Step by Step Implementation
Step 1: Create a New Project
- Open a new project.
- We will be working on Empty Activity with language as Java. Leave all other options unchanged.
- Name the application at your convenience.
- There will be two default files named activity_main.xml and MainActivity.java.
If you don’t know how to create a new project in Android Studio then you can refer to How to Create/Start a New Project in Android Studio?
Step 2. Working on XML files
Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file.
<? xml version = "1.0" encoding = "utf-8" ?>
< LinearLayout
android:layout_width = "match_parent"
android:layout_height = "match_parent"
android:orientation = "vertical"
android:padding = "16dp"
android:gravity = "center"
tools:context = ".MainActivity" >
< Button
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:id = "@+id/bt_alert"
android:text = "Show alert dialog" />
< Button
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:id = "@+id/bt_redirect"
android:text = "Redirect to activity" />
</ LinearLayout >
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Navigate to app > right-click > new > activity > empty activity and name it as “MainActivity2”. Use the following code in activity_main2.xml file
<? xml version = "1.0" encoding = "utf-8" ?>
< LinearLayout
android:layout_width = "match_parent"
android:orientation = "vertical"
android:padding = "16dp"
android:gravity = "center"
android:layout_height = "match_parent"
tools:context = ".MainActivity2" >
< Button
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:id = "@+id/btToast"
android:text = "Display Toast" />
< Button
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:id = "@+id/bt_alert"
android:text = "Display Alert Dialog" />
< Button
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:id = "@+id/bt_redirect"
android:text = "Redirect to activity with text" />
</ LinearLayout >
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Step 3. Working on Java files
Navigate to the MainActivity.java file and use the following code in it. Comments are added to the code to have a better understanding.
package com.example.staticmethod;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
// Initialize variables
Button btAlert,btRedirect;
@Override
protected void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Assign variable
btAlert=findViewById(R.id.bt_alert);
btRedirect=findViewById(R.id.bt_redirect);
btAlert.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
// call static method to display alert dialog
StaticMethod.displayAlertDialog(MainActivity. this ,getString(R.string.app_name), "Welcome to GFG" );
}
});
btRedirect.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
// call static method to redirect activity
StaticMethod.redirect2Activity(MainActivity. this ,MainActivity2. class );
}
});
// Check condition
if (getIntent().hasExtra( "key0" ))
{
// When intent has extra data
// Initialize bundle
Bundle bundle=getIntent().getExtras();
// Check Condition
if (bundle!= null )
{
// When bundle is not equal to null
// get all string
String s1=bundle.getString( "key0" );
String s2=bundle.getString( "key1" );
// Call static method to display toast
StaticMethod.displayToast(MainActivity. this ,s1+ " And " +s2);
}
}
}
} |
Navigate to app > new > class and name it as “StaticMethod”. Use the following code in the StaticMethod.java file
package com.example.staticmethod;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.widget.Toast;
import java.util.ArrayList;
public class StaticMethod {
// Create static method to redirect
public static void redirect2Activity(Activity activity1,Class activity2)
{
// Initialize intent
Intent intent= new Intent(activity1,activity2);
// set flag
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Start activity
activity1.startActivity(intent);
}
// Create static method to redirect
public static void redirectWithText(Activity activity1,Class activity2, ArrayList<String> arrayList)
{
// Initialize intent
Intent intent= new Intent(activity1,activity2);
// Use for loop
for ( int i= 0 ;i<arrayList.size();i++)
{
// Add extra value
intent.putExtra( "key" +i,arrayList.get(i));
}
// Set flag
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
// Start activity
activity1.startActivity(intent);
}
// Create static method to display toast
public static void displayToast(Activity activity,String message)
{
// Initialize toast
Toast.makeText(activity,message,Toast.LENGTH_SHORT).show();
}
// create a static method to display an alert dialog
public static void displayAlertDialog(Activity activity,String title,String message)
{
// Initialize alert dialog
AlertDialog.Builder builder= new AlertDialog.Builder(activity);
// Set title
builder.setTitle(title);
// Set message
builder.setMessage(message);
// Set positive button
builder.setPositiveButton( "OK" , new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
// Dismiss dialog
dialogInterface.dismiss();
}
});
// show dialog
builder.show();
}
// Create static method to display alert dialog with button
public static AlertDialog.Builder displayAlertWithButton(Activity activity,String title,String message)
{
// Initialize alert dialog
AlertDialog.Builder builder= new AlertDialog.Builder(activity);
// set title
builder.setTitle(title);
// set message
builder.setMessage(message);
// Return alert dialog builder
return builder;
};
} |
Navigate to the MainActivity2.java file and use the following code in it. Comments are added to the code to have a better understanding.
package com.example.staticmethod;
import androidx.appcompat.app.AppCompatActivity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import java.util.ArrayList;
public class MainActivity2 extends AppCompatActivity {
// Initialize variables
Button btToast,btAlertDialog,btRedirect;
@Override
protected void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
// Assign variable
btToast=findViewById(R.id.btToast);
btAlertDialog=findViewById(R.id.bt_alert);
btRedirect=findViewById(R.id.bt_redirect);
btToast.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
// Call static method to display toast
StaticMethod.displayToast(MainActivity2. this , "Welcome to GFG" );
}
});
btAlertDialog.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
// Initialize alert dialog
AlertDialog.Builder builder=StaticMethod.displayAlertWithButton(
MainActivity2. this
,getString(R.string.app_name)
, "You want to close the activity?"
);
// Set positive button
builder.setPositiveButton( "Yes" , new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
// finish activity
finish();
}
});
// Set negative button
builder.setNegativeButton( "Cancel" , new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
// Dismiss dialog
dialogInterface.dismiss();
}
});
// Show dialog
builder.show();
}
});
btRedirect.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
// Initialize array list
ArrayList<String> arrayList= new ArrayList<>();
// Add value in array list
arrayList.add( "Text1" );
arrayList.add( "Text2" );
// call static method to redirect with text
StaticMethod.redirectWithText(MainActivity2. this ,MainActivity. class ,arrayList);
}
});
}
} |
Here is the final output of our application.
Output: