Returning Results from an Intent

Returning Results from an Intent

The startActivity() method invokes another activity but does not return a result to the current

activity. For example, you may have an activity that prompts the user for username and password.
The information entered by the user in that activity needs to be passed back to the calling activity for further processing. If you need to pass data back from an activity, you should instead use the startActivityForResult() .

 

 result from an Activity

1. Using the same project created in the previous section, add the following statements in bold to the
main.xml file:

<?xml version=”1.0” encoding=”utf-8”?>
<LinearLayout xmlns:android=”http://schemas.android.com/apk/res/android”
android:orientation=”vertical”
android:layout_width=”fill_parent”
android:layout_height=”fill_parent” >
<TextView
android:layout_width=”fill_parent”
android:layout_height=”wrap_content”
android:text=”Please enter your name” />
<EditText
android:id=”@+id/txt_username”
android:layout_width=”fill_parent”
android:layout_height=”wrap_content” />
<Button
android:id=”@+id/btn_OK”
android:layout_width=”fill_parent”
android:layout_height=”wrap_content”
android:text=”OK” />
</LinearLayout>

2. Add the following statements in bold to Activity2.java:

              package net.learn2develop.Activities;
                import android.app.Activity;
                import android.os.Bundle;
                import android.content.Intent;
                import android.net.Uri;
                import android.view.View;
                import android.widget.Button;
                import android.widget.EditText;
               public class Activity2 extends Activity {
               @Override
   public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
   setContentView(R.layout.activity2);
//---get the OK button---
Button btn = (Button) findViewById(R.id.btn_OK);
//---event handler for the OK button---

btn.setOnClickListener(new View.OnClickListener()
{
      public void onClick(View view) {
          Intent data = new Intent();
        //---get the EditText view---
             EditText txt_username =
             (EditText) findViewById(R.id.txt_username);
             //---set the data to pass back---
              data.setData(Uri.parse(
              txt_username.getText().toString()));
               setResult(RESULT_OK, data);
                //---closes the activity---
                 finish();
         }
      });
     }
 }

3. Add the following statements in bold to the MainActivity.java file:

package net.learn2develop.Activities;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Window;
import android.view.KeyEvent;
import android.widget.Toast;
import android.content.Intent;
public class MainActivity extends Activity {
String tag = “Events”;
int request_Code = 1;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//---hides the title bar---
//requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
Log.d(tag, “In the onCreate() event”);
}
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER)
{
//startActivity(new Intent(“net.learn2develop.ACTIVITY2”));
//startActivity(new Intent(this, Activity2.class));
startActivityForResult(new Intent(“net.learn2develop.ACTIVITY2”),
request_Code);
}
return false;
}
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
if (requestCode == request_Code) {
if (resultCode == RESULT_OK) {
Toast.makeText(this,data.getData().toString(),
Toast.LENGTH_SHORT).show();
}
}
}
public void onStart() { //... }
public void onRestart() { //... }
public void onResume() { //... }
public void onPause() { //... }
public void onStop() { //... }
public void onDestroy() { //... }
}

4. Press F11 to debug the application on the Android Emulator. When the first activity is loaded,
click the center button on the directional pad. Activity2 will now be loaded. Enter your name (see
Figure) and click the OK button. You will see that the first activity now displays the name you
have entered using the Toast class.