An intent can be used for starting another activity. At the same time, it can be used for passing data between activities.
In this demo app, we have two activities where the first activity has an Edittext to receive the user input, a button to trigger the extraction of the user input from the edittext and which is also used for initiating the use of intent to pass data from the current activity to the second.
To follow along, you can create a new project. Update the MainActivity.java file to have the following content.
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText userInput = findViewById(R.id.et_input);
findViewById(R.id.btn).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String information = userInput.getText().toString();
//Todo: handle the case where information is empty
Intent intent = new Intent(getApplicationContext(),
SecondActivity.class);
intent.putExtra("shared_data", information);
startActivity(intent);
}
});
}
}You must have noticed that we are referring to et_input, thus we need to update the layout file.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/darker_gray"
android:padding="8dp">
<EditText
android:id="@+id/et_input"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginLeft="26dp"
android:layout_marginRight="26dp"
android:layout_marginTop="25dp"
android:background="@android:color/white"
android:hint="write something"
android:inputType="text"
android:padding="8dp">
<requestFocus />
</EditText>
<Button
android:id="@+id/btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerInParent="true"
android:background="@android:color/black"
android:text="@string/btn_text"
android:textColor="@android:color/white" />
</RelativeLayout>It is not time to create the second Activity
public class SecondActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_layout);
// todo : get the extras
}
}And we need to update this SecondActivity so that it can extract the data from the MainActivity
Let`s add the following during the onCreate
Bundle extras = getIntent().getExtras();
if (extras != null) {
String retrievedInformation = extras.getString("shared_data");
// todo: do something with the retrievedinformation
}Our final SecondActivity looks like this
public class SecondActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_layout);
Bundle extras = getIntent().getExtras();
if (extras != null) {
String retrievedInformation = extras.getString("shared_data");
// todo: do something with the retrieved information
}
}
}So far so good. We now need to create the sexond_layout.xml which we connect to the SecondActivity.java
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="10dp"
android:orientation="vertical" >
<TextView
android:id="@+id/txtLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="@string/txt_second_layout"
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>We will use the TextView with the id txtLayout to display the data extracted from the MainActivity and
passed to the SecondActivity
Thus we can add the following after we get the data in the SecondActivity
TextView display = findViewById(R.id.txtLayout);
display.setText(retrievedInformation);And our final SecondActivity code looks like this:
public class SecondActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_layout);
Bundle extras = getIntent().getExtras();
if (extras != null) {
String retrievedInformation = extras.getString("shared_data");
TextView display = findViewById(R.id.txtLayout);
display.setText(retrievedInformation);
}
}
}It is good to note that for each Activity you have to ensure that it is declared in the AndroidManifest.xml file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.edu.cqu.buttontoast"
android:versionCode="1"
android:versionName="1.0" >
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="cn.edu.cqu.buttontoast.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="cn.edu.cqu.buttontoast.SecondActivity"
android:label="@string/app_name" >
</activity>
</application>
</manifest>
Feel free to run the application and see the outcome.