Start New Activity - Revision history

Jfreier at 02:27, 1 July 2011

2011-07-01T02:27:31Z

Jfreier at 02:26, 1 July 2011

2011-07-01T02:26:30Z

Jfreier at 14:42, 4 February 2011

2011-02-04T14:42:13Z

Jfreier at 14:40, 4 February 2011

2011-02-04T14:40:38Z

Jfreier: Created page with 'The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code i…'

2011-02-04T14:37:27Z

Created page with 'The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code i…'

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The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code into independent activities, with their own life cycle. More about activity life cycle on the Android developers website.

Easy (just start activity)
Assume you have the MainActivity, and a SecondaryActivity you want to start, this may be done in the easiest way:

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setClassName(this, SecondaryActivity.class.getName());
startActivity(intent);

Medium (pass some params as well)
Now imagine you want to pass some data to the new intent. You will achieve this using the Bundle class, to encapsulate your data. Example:

Intent intent = new Intent();
Bundle bun = new Bundle();

bun.putString(”param_string”, “the actual string”); // add two parameters: a string and a boolean
bun.putBoolean(”param_bool”, true);

intent.setClass(this, SecondaryActivity.class);
intent.putExtras(bun);
startActivity(intent);

In the SecondaryActivity, you will need to access these params. This is how:

Bundle bun = getIntent().getExtras();
String param1 = bun.getString(”param_string”);
boolean param2 = bun.getBoolean(”param_bool”);

Advanced (return some data)
So we passed some parameters to the SecondaryActivity, but let’s assume we want some results as well. From MainActivity one will pack parameters and all others like in the examples above, and than one will call SecondaryActivity as follows:

startActivityForResult(intent, R.id.secondaryactivity_finished);

where secondaryactivity_finished is just some id, that the MainActivity will be looking for in it’s onActivityResult, as follows:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
switch(requestCode)
{
case R.id.secondaryactivity_finished:
if (resultCode == RESULT_OK)
{
Bundle res = data.getExtras();
String result = res.getString(”param_result”);
}
break;
} // end switch
}

In onActivityResult, one simply follows the activities that returned and their error/success codes, and as in the example above may get data passed by the SecondaryActivity. In our case SecondaryActivity returned a string under the name “param_result”.

On the other side, in SecondaryActivity, one will need to pack “param_result” as follows.

private void ReturnToParent()
{
Bundle conData = new Bundle();
conData.putString(”param_return”, “text returned to MainActivity”);
Intent intent = new Intent();
intent.putExtras(conData);
setResult(RESULT_OK, intent);
finish();
}

Some useful default activities:
Part of the beauty of Android is that you can encapsulate other functionality/activities in your own code, just by writing a few lines of code. Below is a list of useful activities one may consider to use:

1. Writing an email

Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”mailto:office@example.com”));
intent.putExtra(”subject”, “my subject”);
intent.putExtra(”body”, “my message”);
startActivity(intent);

2. Browse to a web-page

Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(”http://www.google.com”));
startActivity(intent);

3. Write a SMS

Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”sms://”));
intent.putExtra(”address”, “”);
intent.putExtra(”sms_body”, “my message”);
startActivity(intent);

4. Search something on Google

Intent intent = new Intent(Intent.ACTION_WEB_SEARCH );
intent.putExtra(SearchManager.QUERY, “search this text”);
startActivity(intent);

5. Get the Wiktionary of some word

Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(”http://en.wiktionary.org/wiki/” + “word”));
startActivity(intent);

6. Get the Wikipedia page of some words

String uri = “http://en.wikipedia.org/wiki/” + “my text”;
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
startActivity(intent);

@@ Line 1: / Line 1: @@
 The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code into independent activities, with their own life cycle. More about activity life cycle on the Android developers website.
-With all activities make sure to declare them in the manifest.xml
+With all activities make sure to declare them in the AndroidManifest.xml
   <activity android:name=".MyPasswordsActivity" android:label="MyPasswords"></activity>

← Older revision		Revision as of 02:26, 1 July 2011
Line 1:		Line 1:
	The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code into independent activities, with their own life cycle. More about activity life cycle on the Android developers website.		The Android development paradigm introduces for the developer the “Activity”: <> During development you will find it easy to wrap-up parts of the functionality of your code into independent activities, with their own life cycle. More about activity life cycle on the Android developers website.
		+
		+	With all activities make sure to declare them in the manifest.xml
		+	<activity android:name=".MyPasswordsActivity" android:label="MyPasswords"></activity>

	Easy (just start activity)		Easy (just start activity)

@@ Line 14: / Line 14: @@
   Bundle bun = new Bundle();
-  bun.putString(”param_string”, “the actual string”); // add two parameters: a string and a boolean
+  bun.putString("param_string", "the actual string"); // add two parameters: a string and a boolean
-  bun.putBoolean(”param_bool”, true);
+  bun.putBoolean("param_bool", true);
   intent.setClass(this, SecondaryActivity.class);
@@ Line 55: / Line 55: @@
+  {
      Bundle conData = new Bundle();
-     conData.putString(”param_return”, “text returned to MainActivity”);
+     conData.putString("param_return", "text returned to MainActivity");
      Intent intent = new Intent();
      intent.putExtras(conData);
@@ Line 67: / Line 67: @@
 . Writing an email
-  Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”mailto:office@example.com”));
+  Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse("mailto:office@example.com"));
   intent.putExtra("subject", "my subject");
   intent.putExtra("body", "my message");

@@ Line 13: / Line 13: @@
   Intent intent = new Intent();
   Bundle bun = new Bundle();
-−
   bun.putString(”param_string”, “the actual string”); // add two parameters: a string and a boolean
   bun.putBoolean(”param_bool”, true);
@@ Line 24: / Line 24: @@
   Bundle bun = getIntent().getExtras();
-  String param1 = bun.getString(”param_string”);
+  String param1 = bun.getString("param_string");
-  boolean param2 = bun.getBoolean(”param_bool”);
+  boolean param2 = bun.getBoolean("param_bool");
 Advanced (return some data)
 So we passed some parameters to the SecondaryActivity, but let’s assume we want some results as well. From MainActivity one will pack parameters and all others like in the examples above, and than one will call SecondaryActivity as follows:
-startActivityForResult(intent, R.id.secondaryactivity_finished);
+ startActivityForResult(intent, R.id.secondaryactivity_finished);
 where secondaryactivity_finished is just some id, that the MainActivity will be looking for in it’s onActivityResult, as follows:
-protected void onActivityResult(int requestCode, int resultCode, Intent data)
+ protected void onActivityResult(int requestCode, int resultCode, Intent data)
-−
+ {
-     switch(requestCode)
+      switch(requestCode)
-−
+      {
-         case R.id.secondaryactivity_finished:
+          case R.id.secondaryactivity_finished:
-         if (resultCode == RESULT_OK)
+          if (resultCode == RESULT_OK)
-−
+          {
-         Bundle res = data.getExtras();
+          Bundle res = data.getExtras();
-         String result = res.getString(”param_result”);
+          String result = res.getString(”param_result”);
-−
+          }
-         break;
+          break;
-     } // end switch
+      } // end switch
-−
+ }
-In onActivityResult, one simply follows the activities that returned and their error/success codes, and as in the example above may get data passed by the SecondaryActivity. In our case SecondaryActivity returned a string under the name “param_result”.
+In onActivityResult, one simply follows the activities that returned and their error/success codes, and as in the example above may get data passed by the SecondaryActivity. In our case SecondaryActivity returned a string under the name "param_result".
 On the other side, in SecondaryActivity, one will need to pack “param_result” as follows.
-private void ReturnToParent()
+ private void ReturnToParent()
-−
+ {
-   Bundle conData = new Bundle();
+    Bundle conData = new Bundle();
-   conData.putString(”param_return”, “text returned to MainActivity”);
+    conData.putString(”param_return”, “text returned to MainActivity”);
-   Intent intent = new Intent();
+    Intent intent = new Intent();
-   intent.putExtras(conData);
+    intent.putExtras(conData);
-   setResult(RESULT_OK, intent);
+    setResult(RESULT_OK, intent);
-   finish();
+    finish();
-−
+ }
 Some useful default activities:
@@ Line 67: / Line 67: @@
 . Writing an email
-Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”mailto:office@example.com”));
+ Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”mailto:office@example.com”));
-intent.putExtra(”subject”, “my subject”);
+ intent.putExtra("subject", "my subject");
-intent.putExtra(”body”, “my message”);
+ intent.putExtra("body", "my message");
-startActivity(intent);
+ startActivity(intent);
 . Browse to a web-page
-Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(”http://www.google.com”));
+ Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(”http://www.google.com”));
-startActivity(intent);
+ startActivity(intent);
 . Write a SMS
-Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse(”sms://”));
+ Intent intent = new Intent(Intent.ACTION_SENDTO, Uri.parse("sms://"));
-intent.putExtra(”address”, “”);
+ intent.putExtra("address", "");
-intent.putExtra(”sms_body”, “my message”);
+ intent.putExtra("sms_body", "my message");
-startActivity(intent);
+ startActivity(intent);
 . Search something on Google
-Intent intent = new Intent(Intent.ACTION_WEB_SEARCH );
+ Intent intent = new Intent(Intent.ACTION_WEB_SEARCH );
-intent.putExtra(SearchManager.QUERY, “search this text”);
+ intent.putExtra(SearchManager.QUERY, "search this text");
-startActivity(intent);
+ startActivity(intent);
 . Get the Wiktionary of some word
-Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(”http://en.wiktionary.org/wiki/” + “word”));
+ Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://en.wiktionary.org/wiki/" + "word"));
-startActivity(intent);
+ startActivity(intent);
 . Get the Wikipedia page of some words
-String uri = “http://en.wikipedia.org/wiki/” + “my text”;
+ String uri = "http://en.wikipedia.org/wiki/" + "my text";
-Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
+ Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
-startActivity(intent);
+ startActivity(intent);