How to Continuously Get Data From Another Activity and Change My Ui

This article aims to tell and show how to "Send the data from one activity to second activity using Intent". In this example, we have two activities, activity_first which is the source activity, and activity_second which is the destination activity. We can send the data using the putExtra() method from one activity and get the data from the second activity using the getStringExtra() method.

Pre-requisites:

• Android App Development Fundamentals for Beginners
• Guide to Install and Set up Android Studio
• Android | Starting with the first app/android project
• Android | Running your first Android app

Example:

In this example, one EditText is used to input the text. This text is sent to the second activity when the "Send" button is clicked. For this, Intent will start and the following methods will run:

• putExtra() method is used for sending the data, data in key-value pair key is variable name and value can be Int, String, Float, etc.
• getStringExtra() method is for getting the data(key) that is sent by the above method. according the data type of value there are other methods like getIntExtra(), getFloatExtra()

How to Create an Android App to Send and Receive the Data between Two Activity

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer toHow to Create/Start a New Project in Android Studio. The code for that has been given in both Java and Kotlin Programming Language for Android. This will create an XML file and a Java File. Please refer the pre-requisites to learn more about this step.

Step 2: Working with the XML Files

Next, go to the activity_main.xml file, which represents the UI of the project. Below is the code for theactivity_main.xml file. Comments are added inside the code to understand the code in more detail. Open the "activity_first_activity.xml" file and add the following widgets in a Relative Layout .

• An EditText to Input the message
• A Button to send the data

Also, Assign the ID to each component along with other attributes as shown in the image and the code below. The assigned ID on a component helps that component to be easily found and used in the Java/Kotlin files.

Syntax:

android:id="@+id/id_name"

Here the given IDs are as follows:

• Send Button: send_button_id
• input EditText: send_text_id

XML

<? xml version = "1.0" encoding = "utf-8" ?>

android:layout_width = "match_parent"

android:layout_height = "match_parent"

tools:context = ".first_activity" >

< EditText

android:id = "@+id/send_text_id"

android:layout_width = "300dp"

android:layout_height = "wrap_content"

android:layout_marginLeft = "40dp"

android:layout_marginTop = "20dp"

android:hint = "Input"

android:textSize = "25dp"

android:textStyle = "bold" />

< Button

android:id = "@+id/send_button_id"

android:layout_width = "wrap_content"

android:layout_height = "40dp"

android:layout_marginLeft = "150dp"

android:layout_marginTop = "150dp"

android:text = "send"

android:textStyle = "bold" />

</ RelativeLayout >

This will make the UI of the Application

Step 3: Working with the MainActivity File

Go to the MainActivity File and refer to the following code. Below is the code for the MainActivity File. Comments are added inside the code to understand the code in more detail. Now, after the UI, this step will create the Backend of the App. For this, open the "first_activity" file and instantiate the components made in the XML file (EditText, send Button) using findViewById() method. This method binds the created object to the UI Components with the help of the assigned ID.

Syntax: General

ComponentType object = (ComponentType)findViewById(R.id.IdOfTheComponent);

Syntax: for components used is as follows:

Button send_button= findViewById(R.id.send_button_id);  send_text = findViewById(R.id.send_text_id);

Setting up the Operations for the Sending and Receiving of Data.

These Operations are as follows:

Add the listener to the send button and this button will send the data.

This is done as follows:

send_button.setOnClickListener(v -> {}        

after clicking this button following operation will be performed

Now create the String type variable to store the value of EditText which is input by the user. Get the value and convert it to string.

This is done as follows:

String str = send_text.getText().toString();

Now create the Intent object First_activity.java class to Second_activity class.

This is done as follows:

Intent intent = new Intent(getApplicationContext(), Second_activity.class);

where getApplicationContext() will fetch the current activity.

Put the value in the putExtra method in the key-value pair then start the activity.

This is done as follows:

intent.putExtra("message_key", str);  startActivity(intent);

where "str" is the string value and the key is "message_key" this key will use to get the str value

Java

import android.content.Intent;

import android.os.Bundle;

import android.widget.Button;

import android.widget.EditText;

import androidx.appcompat.app.AppCompatActivity;

public class first_activity extends AppCompatActivity {

Button send_button;

EditText send_text;

@Override

protected void onCreate(Bundle savedInstanceState) {

super .onCreate(savedInstanceState);

setContentView(R.layout.activity_first_activity);

send_button = findViewById(R.id.send_button_id);

send_text = findViewById(R.id.send_text_id);

send_button.setOnClickListener(v -> {

String str = send_text.getText().toString();

Intent intent = new Intent(getApplicationContext(), Second_activity. class );

intent.putExtra( "message_key" , str);

startActivity(intent);

});

}

}

Kotlin

import android.content.Intent

import android.os.Bundle

import android.widget.Button

import android.widget.EditText

import androidx.appcompat.app.AppCompatActivity

class first_activity : AppCompatActivity() {

lateinit var send_button: Button

lateinit var send_text: EditText

override fun onCreate(savedInstanceState: Bundle?) {

super .onCreate(savedInstanceState)

setContentView(R.layout.activity_first_activity)

send_button = findViewById(R.id.send_button_id)

send_text = findViewById(R.id.send_text_id)

send_button.setOnClickListener {

val str = send_text.text.toString()

val intent = Intent(applicationContext, Second_activity:: class .java)

intent.putExtra( "message_key" , str)

startActivity(intent)

}

}

}

Step 4: Creating Second_Activity to Receive the Data.

The steps to create the second activity are as follows:

android project > File > new > Activity > Empty Activity        

Step 5: Working with the Second XML File

Add TextView to display the received messages. assign an ID to Textview.

XML

<? xml version = "1.0" encoding = "utf-8" ?>

android:layout_width = "match_parent"

android:layout_height = "match_parent"

tools:context = "org.geeksforgeeks.navedmalik.sendthedata.Second_activity" >

< TextView

android:id = "@+id/received_value_id"

android:layout_width = "300dp"

android:layout_height = "50dp"

android:layout_marginLeft = "40dp"

android:layout_marginTop = "20dp"

android:textSize = "40sp"

android:textStyle = "bold"

android:layout_marginStart = "40dp" />

</ RelativeLayout >

The Second Activity is shown below:

Step 6: Working with the SecondActivity File

Define the TextView variable, use findViewById() to get the TextView as shown above.

receiver_msg = (TextView) findViewById(R.id.received_value_id);        

Now In the second_activity.java file create the object of getIntent to receive the value in String type variable by the getStringExtra method using message_key.

Intent intent = getIntent();  String str = intent.getStringExtra("message_key");

The received value set in the TextView object of the second activity XML file

receiver_msg.setText(str);

Java

import android.content.Intent;

import android.os.Bundle;

import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

public class Second_activity extends AppCompatActivity {

TextView receiver_msg;

@Override

protected void onCreate(Bundle savedInstanceState) {

super .onCreate(savedInstanceState);

setContentView(R.layout.activity_second_activity);

receiver_msg = findViewById(R.id.received_value_id);

Intent intent = getIntent();

String str = intent.getStringExtra( "message_key" );

receiver_msg.setText(str);

}

}

Kotlin

import android.os.Bundle

import android.widget.TextView

import androidx.appcompat.app.AppCompatActivity

class Second_activity : AppCompatActivity() {

lateinit var receiver_msg: TextView

override fun onCreate(savedInstanceState: Bundle?) {

super .onCreate(savedInstanceState)

setContentView(R.layout.activity_second_activity)

receiver_msg = findViewById(R.id.received_value_id)

val intent = intent

val str = intent.getStringExtra( "message_key" )

receiver_msg.text = str

}

}

Output:

byarscapaidep.blogspot.com

Source: https://www.geeksforgeeks.org/how-to-send-data-from-one-activity-to-second-activity-in-android/

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