Passing data to sub-activities in android: 

• Getting started, to pass data from sub-activities, first, you know what is activities and sub-activities in android.
  The activity represents a current screen or single screen in android. It is like a frame or window in AWT.
  And here we simply describe sub-activity, create two activity in android, activity first & second, and activity first send data or perform other tasks to the second activity, then activity second is usually referred as a “sub-activity” of first activity.
  
  
  Example :
  Create Two Layouts file for activity & sub-activities:
  
  
  activity_first_main.xml
  
  

  <?xml version="1.0" encoding="utf-8"?>
  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="com.example.msclient009.opennewactivity.FirstMainActivity">
      <TextView
          android:id="@+id/textView"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="44dp"
          android:text="First Activity"
          android:textColor="#00f"
          android:textSize="30dp"
          android:textStyle="bold"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toTopOf="parent" />
      <EditText
          android:id="@+id/editText"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_below="@+id/textView"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="79dp"
          android:hint="Enter Your Name...." />
      <Button
          android:id="@+id/button1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_below="@+id/editText"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="64dp"
          android:background="#000"
          android:padding="10dp"
          android:text="Click Here to pass data from sub-activity"
          android:textColor="#fff" />
  </RelativeLayout>

  
  
  activity_second_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">
      <TextView
          android:id="@+id/textView1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="110dp"
          android:text="Sub-Activity"
          android:textColor="#00f"
          android:textStyle="bold"
          android:textSize="30dp" />
      <TextView
          android:id="@+id/textView2"
          android:layout_width="200dp"
          android:layout_height="wrap_content"
          android:layout_below="@+id/textView1"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="99dp"
          android:background="#f00"
          android:paddingLeft="20dp"
          android:paddingStart="20dp"
          android:text="Arti mishra"
          android:textColor="#fff"
          android:textSize="30dp" />
  </RelativeLayout>

  
  
  Create Java file for activity & sub-activity layout files:
  • FirstMainActivity.java is a simple java class to implementing setOnClickListener() method to handle button click event.
  • When the user clicks on the button then we create the intent, put some data and pass it to startActivity(intent) method.
  • For inserting a data we can use putExtra(key, value) method.
  
  
  FirstMainActivity.java
  
  

  package com.example.msclient009.opennewactivity;
  import android.content.Intent;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.Button;
  import android.widget.EditText;
  public class FirstMainActivity extends AppCompatActivity {
      EditText editText;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_first_main);
          Button button=(Button)findViewById(R.id.button1);
           editText=(EditText)findViewById(R.id.editText);
          button.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View view) {
                  String str=editText.getText().toString();
                  Intent intent=new Intent(FirstMainActivity.this, NewMainActivity.class);
                  intent.putExtra("Name", str);
                  startActivity(intent);
              }
          });
      }
  }

  
  
  • SubActivity.java is the activity we want to start. It contains two text view to display data or any message sent from the FirstMainActivity.java.
  • For extracting the sent message from FirstMainActivity.java file we can use getIntent().getStringExtra(“message”) method.
  
  
  SubActivity.java
  
  

  package com.example.msclient009.opennewactivity;
  import android.app.Activity;
  import android.content.Intent;
  import android.os.Build;
  import android.os.Bundle;
  import android.support.annotation.RequiresApi;
  import android.widget.TextView;
  public class SubActivity extends Activity {
   TextView textView;
      @RequiresApi(api = Build.VERSION_CODES.N)
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_second_main);
          textView=(TextView)findViewById(R.id.textView2);
          Intent intent=getIntent();
          String str = intent.getStringExtra("Name");
          textView.setText(str);
      }
  }

  
  
  Define Activities in the Manifest.XML File :
  
  

  <?xml version="1.0" encoding="utf-8"?>
  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.msclient009.opennewactivity">
      <application
          android:allowBackup="true"
          android:icon="@mipmap/ic_launcher"
          android:label="@string/app_name"
          android:roundIcon="@mipmap/ic_launcher_round"
          android:supportsRtl="true"
          android:theme="@style/AppTheme">
          <activity android:name=".FirstMainActivity">
              <intent-filter>
                  <action android:name="android.intent.action.MAIN" />
                  <category android:name="android.intent.category.LAUNCHER" />
              </intent-filter>
          </activity>
          <activity
              android:name=".SubActivity"
              android:label="@string/app_name" >
          </activity>
      </application>
  </manifest>

  
  
  Output :
  
  
  
  
  
  
•