Develop Reference

what will be the method to pass information to another target of intent class in androiod

Which method of the Intent class allows you to pass information to the target? the answer must be putExtra(); but this is not the right answer.

Try using:
putExtra
not
putExtra();

ADT: Avoid duplicating code in package with dependency on another deployed package?

When I have e.g. a custom service and a custom activity in the same ADT project, then I can use this in the service, to start my activity:
Intent i = new Intent(context, MyCustomActivity.class);
startActivity(i);
However when I have the service and activity in separate projects, then I cannot do this since I do not have a direct reference to MyCustomActivity.class. This is problematic: I do not wish to include a JAR just to be able to fix that broken reference, since I assume this will increase the package size and create redundant data on the device (i.e. activity code is duplicated between the service and activity packages). So instead, I use this (perhaps there are other options?):
Intent i = new Intent("com.mypackage.myStringActionName");
startActivity(i); //is this a broadcast?
OR
Intent i = new Intent("com.mypackage.myStringActionName");
sendBroadcast(i);
...But I don't really like sending broadcasts when all I want is to direct the intent to a single activity to tell it to start.
So, what other ways are there to go about avoiding duplication (in ADT)? Or else a better way to send direct intents?

you can try this:
Intent i = new Intent();
i.setComponent(new ComponentName(packageName, classname));
startActivity(i);
the className must contains the packageName and main activity name

Use of Context to start another Activity

To start an Activity you need an Intent, like:
Intent i = new Intent(context, class)
So to fill in the context parameter, a couple of options are available:
Use MyActivity.this or just this
Use getApplicationContext()
Use getBaseContext()
And I'm sure there are one or two more options.
These options all appear in some sort of tutorial, one uses the first, the next uses the third option.
So which one should I use? Does it even matter? Is it different for different cases?

Yes its different for different cases,
It depends on the scope. Suppose if you are creating a method in a global class that extends Application to create a Toast that is used in every class of your Application you can use getApplicationContext() to create it.
If you want to create a view that is restricted to that particular Activity you can use Activity.this
Also if you want to create an AlertDialog in some inner class say AsyncTask, then you have to use Activity.this, because the AlertDialog is to be linked to Activity itself.
Also don't use getBaseContext() just use the Context that you are having. For getting further information for the same you can see this Answer.
So, the answer to the real question is better to use Activity.this to start a new Activity.
Intent intent = new Intent(Current_Activity.this, Calling.class);
startActivity(intent);

They are different for sure. These are different contexts, and should be used with the least possible scope(context).
For example if we can use Activity's Context instead of ApplicationContext, one should use the activity context, same applies to application context, and base context.

You do it like this....
Intent intent = new Intent();
intent.setClass(MainActivity.this, SecondActivity.class);
startActivity(intent);

Constructors in Android Programming?

I have some values and want to pass with activity so that I can show in TextViews of Activity, I am unable to understand such a concept, so what should I do?
Simply I want to make constructor but unable to understand it that how will it be done, I am new to android programming, so needed help.

Start by reading the documentation at developer.android.com about intents and intent extras.

In android if you launched an activity there is a method called onCreate execute automatically.You can send values using Intent to the activity and can retrieve them in the Activity

The Activity (sub)class must have a default constructor without any parameters so that the system can instanciate it at run time.
To pass "parameters" to activities, you need to use the extra bundle of the intent.
Intent i = new Intent(this, MyActivity.class);
i.putExtra("com.sample.MyParameter", 666);
startActivity(i);
See Starting An Activity

If you want to pass one value then you can use intent but if you want to pass multiple values then using "Bundle" is best way.
Bundle bundel = new Bundle();
bundel.putStringArray("key1",strings);
bundel.putStringArray("key2",stringsofids);
bundel.putString("key3", str31);
bundel.putStringArray("key4",stringsbakup);
bundel.putString("key5", str1);
bundel.putString("key6", str4);

android switchstatement question

I was wondering, how would I make a switch statement, that when that certain case was triggered, it would open a new screen with text. Would I use an intent? And if so, which one?
Thank you for your help in advance.

When you want to open a "new screen", you probably want to open a new activity. You would create a second Activity-derived class and use the following overload of the Intent constructor with startActivity:
Intent intent = new Intent(this, MySecondActivity.class);
startActivity(intent);
this will explicitly attempt to open a new Activity with the class name MySecondActivity
to pass a String of text from one Activity to another in this way, you can add it to the intent.
String someValue = "Some Value";
intent.putExtra("Some Key", someValue);
and in the code of your other Activity, you can get at this string via the Intent
getIntent().getStringExtra("Some Key");
Obviously you want to do null checks to make sure the key exists in the Intent, and you want to put a proper constant String somewhere instead of using a literal String for a key, but this is the basic gist.

Kriem... As Rich said you can launch a new activity using intents and push data to the new activity using extras. You can push data back to your main activity using startActivityForResult instead of startActivity. You can return to your main screen by calling finish() in the new screen. Finally, you can put the new screen event handlers into the NewScreen.java file.
The overall effect is a near full separation from dependency between the two activities, so that you might be able to easily re-use the NewScreen.java class in another project. I have some code here.